Reference: Halton Region Health Department, 2017 Annual Infectious Disease Report. Oakville, Ontario, July 2018.

Transcription

1

2 Reference: Halton Region Health Department, 2017 Annual Infectious Disease Report. Oakville, Ontario, July Author: Kendra Habing, Epidemiologist Acknowledgements: Cate Bannan, Manager Sexual Health and Needle Exchange Maria Bohorquez, Director Clinical Health Services Megan Brunner, Epidemiologist Kathy Jovanovic, Manager Communicable Disease Control Sarah Phillips, Acting Manager Enteric and Vector-borne Disease Matt Ruf, Director Healthy Environments and Communicable Disease Department Tetyana Seminska, Manager Food Safety Emma Tucker, Manager and Senior Epidemiologist Kristen Wheeler, Epidemiologist 2017 Halton Region Infectious Disease Report

3 Table of Contents Executive Summary... 1 Introduction... 3 Presentation of the results... 3 Part I: Leading reportable infectious diseases in 2017 in Halton... 5 Comparison with Ontario: age-standardized incidence ratios for Part II: Categories of infectious diseases... 8 Vaccine-preventable diseases... 8 Influenza 10 Streptococcus pneumoniae 11 Chickenpox (varicella) 12 Pertussis (whooping cough) 13 Mumps 14 Measles 15 Invasive meningococcal disease 15 Hepatitis B 16 Invasive Haemophilus influenzae b disease 16 Tetanus 17 Rubella 17 Diphtheria 17 Polio 18 Smallpox 18 Food- and water-borne diseases Campylobacter enteritis 20 Salmonellosis 21 Giardiasis 22 Amebiasis 23 Cyclosporiasis 24 Yersiniosis 25 Cryptosporidiosis 26 Shigellosis 27 Legionellosis 28 Verotoxin-producing E. coli with haemolytic uraemic syndrome 29 Hepatitis A 30 Listeriosis 30 Paratyphoid fever 30 Typhoid fever 31 Botulism 31 Cholera 31 Trichinosis 32 Paralytic shellfish poisoning 32 Sexually-transmitted and blood-borne infections Chlamydia 34 Gonorrhoea 36 Hepatitis C 38 Syphilis 39 HIV and AIDS 40 Chancroid 41 Neonatal infectious diseases Neonatal group B streptococcal disease 42 Early congenital syphilis Halton Region Infectious Disease Report

4 Congenital rubella syndrome 42 Opthalmia neonatorum 43 Zoonotic, vector-borne, and exotic diseases Lyme disease 45 Malaria 46 West Nile virus illness 46 Q fever 46 Brucellosis 47 Leprosy 47 Hemorrhagic fevers 47 Tularemia 48 Yellow fever 48 Rabies 48 Psittacosis/ornithosis 49 Anthrax 49 Lassa fever 50 Hantavirus pulmonary syndrome 50 Plague 50 Other reportable infectious diseases Encephalitis and meningitis 52 Invasive group A streptococcal disease 53 Tuberculosis 54 Acute flaccid paralysis 55 Creutzfeldt-Jakob disease 55 Severe Acute Respiratory Syndrome 55 Part III: Infectious diseases and the social determinants of health...56 Part IV: Outbreak investigations...58 Respiratory outbreaks Agent 59 Location 60 Seasonal variation 60 Outbreak duration 61 Number of cases investigated 61 Enteric outbreaks Agent 62 Location 63 Seasonal variation 63 Outbreak duration 64 Number of cases investigated 64 Conclusion...65 References...66 Appendix A: O. Reg 559/91 under the Health Protection and Promotion Act...67 Appendix B: Data notes and limitations...69 Definitions Data Sources iphis data extraction logic Limitations Appendix C: Summary table of case definitions...71 Appendix D: Summary of counts and rates of reportable infectious diseases Halton Region Infectious Disease Report

5 List of Figures Figure 1: Top ten most frequently reported infectious diseases in Halton residents, Figure 2: Age-standardized incidence ratios for the top ten most frequently reported infectious diseases, Halton and Ontario, Figure 3: Most frequently reported vaccine-preventable diseases compared to previous five-year average, Halton residents, Figure 4: Influenza crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, (calendar year) Figure 5: Streptococcus pneumoniae crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 6: Pertussis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 7: Mumps crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 8: Most frequently reported food- and water-borne diseases compared to previous fiveyear average, Halton residents, Figure 9: Campylobacter enteritis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 10: Salmonellosis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 11: Giardiasis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 12: Amebiasis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 13: Cyclosporiasis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 14: Yersiniosis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 15: Cryptosporidiosis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 16: Shigellosis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 17: Legionellosis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 18: Verotoxin-producing E. coli crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 19: Most frequently reported sexually-transmitted and blood-borne infections in Halton compared to previous five-year average, Halton residents, Figure 20: Chlamydia crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 21: Chlamydia age-specific incidence rates (per 100,000), by sex, Halton residents, Figure 22: Gonorrhoea crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 23: Gonorrhoea age-specific incidence rates (per 100,000), by sex, Halton residents, Figure 24: Hepatitis C crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 25: Syphilis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Halton Region Infectious Disease Report

6 Figure 26: HIV crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 27: Most frequently reported zoonotic and exotic infections in Halton compared to previous five-year average, Halton residents, Figure 28: Lyme disease crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 29: Other reportable diseases compared to previous five-year average, Halton residents, Figure 30: Encephalitis and meningitis combined* crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 31: Invasive Group A streptococcal disease crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 32: Tuberculosis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Figure 33: Age-standardized incidence rates (per 100,000), by neighbourhood income group, Halton Region, Figure 34: Respiratory outbreaks investigated in Halton by agent, 2017 compared to average Figure 35: Respiratory outbreaks investigated in Halton, by location, 2017 compared to average Figure 36: Respiratory outbreaks investigated in Halton, by month of onset, Figure 37: Respiratory outbreaks investigated in Halton, by duration, 2017 compared to average Figure 38: Enteric outbreaks investigated in Halton, by agent, 2017 compared to average Figure 39: Enteric outbreaks investigated in Halton, by location, 2017 compared to average Figure 40: Enteric outbreaks investigated in Halton, by month of onset, Figure 41: Enteric outbreaks investigated in Halton, by duration, 2017 compared to average List of Tables Table 1: Number, crude rate, and age-standardized rate of the top ten most frequently reported infectious diseases in Halton residents, Table 2: Total number of clients and staff who were at risk and who were ill, by location of the outbreak, respiratory outbreaks, Halton Region, Table 3: Total number of clients and staff who were at risk and who were ill, by location of the outbreak, enteric outbreaks, Halton Region, Table 4: Summary table of provincial case definitions, adapted from the 2017 Infectious Diseases Protocol (Appendix B) Table 5: Summary of counts, crude rates, crude rate ratio, age-standardized rates, and agestandardized rate ratio for reportable infectious diseases, Halton and Ontario, Halton Region Infectious Disease Report

7 Executive Summary The Halton Region Health Department works towards the goal of reducing the incidence of infectious diseases in the community through a variety of programs and services, including investigating individual cases and responding to outbreaks, inspecting retail food services and personal service settings, health promotion campaigns, and providing immunizations and other clinical services. Reportable infectious diseases in Halton Reportable infectious diseases are diseases that are required under the Health Protection and Promotion Act 1 to be reported to the local Medical Officer of Health. In 2017, 2,475 cases of reportable infectious diseases were reported to the Halton Region Health Department. The top five most common reportable infectious diseases in Halton in 2017 were: 1. Chlamydial infections 2. Influenza 3. Gonorrhoea 4. Campylobacter enteritis 5. Salmonellosis Vaccine-preventable diseases are diseases for which an effective vaccine exists. In 2017, 500 Halton residents were diagnosed with a vaccine-preventable disease, accounting for 20% of all reportable diseases that year. Age-standardized rates of vaccine-preventable diseases in 2017 were similar or lower in Halton compared to Ontario. The most commonly reported vaccinepreventable disease was influenza (439 cases); however the true number of influenza cases in the population is likely to be much higher, as many people may not seek medical treatment or receive laboratory testing for influenza and therefore cases are not reported. Food- and water-borne diseases are caused by bacteria, parasites, and viruses that have found their way into food or water that is being consumed. In 2017, there were 392 reported cases of food and water-borne diseases among Halton residents, accounting for 16% of the total cases of reportable infectious diseases that year. The most commonly reported food- and water-borne diseases in 2017 were Campylobacter enteritis (152 cases) and salmonellosis (114 cases). Age-standardized rates of food- and water-borne diseases in Halton were similar or lower compared to Ontario. In 2017, 41% of food- and water-borne illnesses with a known risk factor/exposure in Halton were associated with travel outside of Canada. Sexually-transmitted and blood-borne infections are the most common category of reportable infectious diseases in Halton. In 2017, there were 1,479 reported cases of sexuallytransmitted infections (STIs) and blood-borne infections among Halton residents, accounting for over half (60%) of all reportable diseases in Halton. Chlamydia was the most commonly reported infectious disease in Halton (1,148 cases). Other common STIs and blood-borne infections include gonorrhoea (179 cases) and hepatitis C (102 cases). In general, rates of STIs and blood-borne infections are lower in Halton compared to Ontario. In recent years, Halton has seen an increase in reported cases of gonorrhoea and chlamydia, consistent with the overall trend in Ontario Halton Region Infectious Disease Report 1

8 Reportable neonatal infectious diseases are transferred from mother to infant either through the placenta, or through the birth canal during delivery. In 2017, there were two cases of reportable neonatal disease. Zoonotic diseases are diseases that can be passed from animals to humans. Vector-borne diseases are spread to people by small organisms such as mosquitoes and ticks. In 2017, there were 26 cases of zoonotic or vector-borne diseases reported in Halton, accounting for just over 1% of all reportable diseases. The most commonly reported vector-borne disease was Lyme disease (13 cases). Halton had six reported cases of West Nile virus illness in 2017, which was similar to the previous five year average (6 cases). There were an additional 77 cases of other reportable diseases (meningitis/encephalitis, group A streptococcal disease, tuberculosis, meningococcal disease, and Cruetzfeldt-Jakob disease) reported to the Halton Region Health Department in 2017, accounting for 3% of all reportable diseases in Halton. Rates of encephalitis/meningitis combined in Halton in 2017 were significantly higher than Ontario. Rates of tuberculosis in Halton in 2017 were significantly lower than Ontario. Infectious diseases and the social determinants of health Social determinants of health reflect the social and physical conditions where people live, learn, work, and play. Due to the influence of the social determinants of health, the burden of infectious disease is not evenly distributed across the population. In 2017, the rate of reportable infectious diseases in Halton was highest in the low neighbourhood income group. However, in Halton, there are very few neighbourhoods in Halton that are considered to be in the low income group. Therefore, although the rate of reportable infectious diseases was highest in the low neighbourhood income group, there were only 124 cases reported, compared to 1650 cases reported in the high neighbourhood income group. Outbreak investigations Halton Region Health Department staff members investigate outbreaks in order to decrease or eliminate health risks presented by infectious diseases. All institutional enteric and respiratory outbreaks are reportable to the Health Department, regardless of whether or not the specific disease is known or reportable. In 2017, there were 85 confirmed and suspect respiratory institutional outbreaks investigated by the Health Department. The majority of respiratory outbreaks investigated by the Health Department involved long-term care homes (72%), followed by retirement residences (18%), unregulated or special homes (4%), child care centres (2%), community settings (2%), and hospitals (2%). The most common agents were influenza A (35%), unspecified respiratory agents (20%), and rhinovirus (8%). In 2017, there were 44 confirmed enteric institutional outbreaks investigated by the Health Department. The majority of enteric outbreaks investigated by the Health Department occurred in child care centres (45%), followed by long-term care homes (30%), retirement residences (20%), and community settings (5%). Over half the agents involved in enteric outbreaks were unspecified (61%), but the most common known agent was norovirus (32%) Halton Region Infectious Disease Report 2

9 Introduction The 2017 Halton Region Infectious Disease Report summarizes the incidence of infectious diseases that were reported to the Health Department for Halton Region residents in These diseases are caused by a variety of organisms including bacteria, viruses, and protozoa, or through toxins from these organisms. Infectious diseases are spread from one host to another through close personal contact, sexual contact, contaminated food or water, animals, or other environmental sources. The current list of infectious diseases that must be reported to the local Medical Officer of Health under the Health Protection and Promotion Act (HPPA) 2 is shown in Appendix A. Under the Health Protection and Promotion Act, outbreaks in any institutions of any infectious disease must also be reported. The 2017 Halton Region Infectious Disease Report reflects the surveillance and health status reporting function that the Health Department is mandated to perform in order to monitor the impact of infectious disease programs and to identify significant or emerging issues. The Health Department works towards the goal of reducing the incidence of infectious diseases in the community through the delivery of various programs. Staff members investigate reports of individual cases and respond to outbreaks in both the community and in institutions such as long-term care homes, retirement homes, acute care settings, child care settings, schools, colleges, and correctional institutions. In addition to investigating disease reports and preventing further spread of disease, the Health Department also conducts inspections of licensed child care settings, personal service settings, food premises, small drinking water systems, and public spas and swimming pools. Finally, the Health Department is mandated to provide education and certification programs, such as food handler training, as well as clinical services, such as immunization and sexual health clinics, which help to prevent and reduce the burden of infectious diseases. Presentation of the results This report is divided into four different sections: Part I: Leading reportable infectious diseases in 2017 in Halton provides an overview of the top ten most commonly reported infectious diseases in Halton. Part II: Categories of infectious diseases provides an in-depth look at the counts and rates of each reportable disease under the HPPA 1 in Halton compared to Ontario. Trends over time are presented in graphs for diseases with five or more cases in Age and sex distributions are also presented for the most common sexually transmitted infections in Halton. Part III: Infectious diseases and the social determinants of health examines the relationship between income and the incidence of reportable infectious diseases in Halton in Part IV: Outbreak investigations presents a summary of respiratory and enteric outbreak investigations conducted by the Health Department in Halton Region Infectious Disease Report 3

10 Infectious disease data are presented as counts, crude rates, age-standardized rates, and agespecific rates: Crude incidence rates are used to get an actual depiction of the incidence of infectious diseases in Halton. It should not be used to directly compare two different populations (such as Halton and Ontario), as crude rates are influenced by the age structure of a population. Age-standardized incidence rates are used to compare the different populations of Halton and Ontario, as well as neighbourhood income groups. The rates are standardized to the 2011 Canadian population. This ensures that any differences in rate between populations are not due to differences in the age distributions between populations. Age-standardized rates provide an overall rate for all ages combined. Age-specific rates are used to make comparisons between age groups in Halton. Agespecific rates allow for comparisons by age group and sex to determine if certain age groups are more likely than others to have particular infectious diseases. Age-specific rates are presented for the most common sexually transmitted reportable infectious diseases in Halton. Trends over time were tested for significance using linear regression and adjusting for autocorrelation. Please note that the upper limit of the Y-axis scale used in each graph differs. Deaths among Halton residents who had been diagnosed with a reportable disease may not have been attributed to the reportable disease itself. The data presented in this report are from the Integrated Public Health Information System (iphis). iphis is a dynamic disease reporting system which allows ongoing updates to data previously entered. As a result, data extracted from iphis represent a snapshot at the time of extraction and may differ from previous or subsequent reports. For more information on limitations of this report, as well as data extraction logic, see Appendix B: Data notes and limitations. The Provincial Case Definitions 3 from the Infectious Diseases Protocol, 2017 were used to determine what was considered a case. For certain diseases, only confirmed cases are counted, whereas others include probable and/or suspect cases as well. For a summary table of the case definitions used in this report, see Appendix C: Summary table of case definitions. Descriptions of each reportable disease were adapted from the Disease Specific Chapters 4 of the Infectious Diseases Protocol, When interpreting trends over time, it is important to consider changes to case definitions and laboratory testing. For example, Ontario adopted new case definitions for all reportable diseases in April 2009 and additional updates to case definitions for certain diseases have occurred in subsequent years. Therefore comparisons of data before and after April 2009, as well as any additional years where definitions have changed, should be interpreted with caution. Only cases of disease that were reported to the Health Department are captured in this report. Individuals who do not experience any symptoms or only experience mild symptoms may not seek medical attention or may not be tested for a specific disease, and would not be captured in this report. This report therefore likely underestimates the true rates of infectious diseases in the population, especially for common, milder illnesses, such as many food- and water-borne infections Halton Region Infectious Disease Report 4

11 Part I: Leading reportable infectious diseases in 2017 in Halton In 2017, 2,475 cases of reportable infectious diseases were reported to the Halton Region Health Department. Table 1 shows the ten most frequently reported infectious diseases, which accounted for 92% of the total cases. Figure 1 shows the number of cases of these diseases in 2017 compared to the previous five-year annual average. For a summary of the counts, crude rates, and agestandardized rates of reportable diseases in Halton, including comparisons to previous years, see Appendix D: Summary of counts and rates of reportable infectious diseases. Table 1: Number, crude rate, and age-standardized rate of the top ten most frequently reported infectious diseases in Halton residents, 2017 Total Reported Confirmed Cases Crude Incidence Rate per 100,000 Age-Standardized Incidence Rate per 100,000 Chlamydia Influenza Gonorrhoea Campylobacter enteritis Salmonellosis Hepatitis C Encephalitis/meningitis* Giardiasis Syphilis** Streptococcus pneumoniae, invasive Total number of reported cases of the top ten diseases All other reported cases Total number of reported cases in Source: Integrated Public Health Information System [2017], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, *Includes primary viral and unspecified encephalitis; encephalitis/meningitis; bacterial, other, and viral meningitis **Excludes early congenital syphilis 2017 Halton Region Infectious Disease Report 5

12 Number of reported cases average Figure 1: Top ten most frequently reported infectious diseases in Halton residents, Source: Integrated Public Health Information System [ ], extracted March 7, *Includes primary viral and unspecified encephalitis; encephalitis/meningitis; bacterial, other, and viral meningitis **Excludes early congenital syphilis 2017 Halton Region Infectious Disease Report 6

13 Comparison with Ontario: age-standardized incidence ratios for 2017 Figure 2 shows the incidence ratio for the top ten infectious diseases in Halton in 2017 compared to Ontario. If the confidence interval (CI) falls completely to the left of the line, it indicates that Halton s rate was statistically significantly lower than Ontario s rate. If the CI falls completely to the right of the line it means Halton s rate was statistically significantly higher than Ontario s rate. If the incidence ratio or corresponding CI touch the line, then there was no statistically significant difference between Halton and Ontario. As seen in Figure 2, Halton had significantly lower age-standardized rates of chlamydia, gonorrhoea, hepatitis C, syphilis, and invasive streptococcus pneumoniae compared to Ontario. Halton had a significantly higher age-standardized rate of encephalitis/meningitis compared to Ontario. There were no statistically significant differences between Halton and Ontario in the age-standardized rate of any of the remaining top ten most frequently reported infectious diseases in Halton. For a comparison of rates and incidence ratios for common reportable diseases for Halton and Ontario, see Appendix D: Summary of counts and rates of reportable infectious diseases. Chlamydia Influenza Gonorrhoea (all types) Campylobacter enteritis Salmonellosis Hepatitis C Encephalitis/meningitis* Giardiasis Syphilis** Streptococcus pneumoniae, invasive Figure 2: Age-standardized incidence ratios for the top ten most frequently reported infectious diseases, Halton and Ontario, Sources: Integrated Public Health Information System [2017], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018]. *Includes primary viral and unspecified encephalitis; encephalitis/meningitis; bacterial, other, and viral meningitis **Excludes early congenital syphilis 2017 Halton Region Infectious Disease Report 7

14 Part II: Categories of infectious diseases Vaccine-preventable diseases This section provides an overview of vaccine-preventable diseases reported to the Health Department in Vaccine-preventable diseases (VPDs) are diseases for which an effective vaccine exists. For the purposes of this report, there are 14 reportable diseases that are considered vaccine-preventable because they are part of Ontario s routine immunization program, publicly funded (influenza), or have been eradicated through vaccination (smallpox). Vaccines have played a key role in reducing the burden of many diseases and have even eradicated (i.e. world-wide) or eliminated (i.e. continent-wide) some diseases that in the past century caused major illnesses and loss of life. Illness from nine infectious diseases (smallpox, diphtheria, pertussis, tetanus, polio, measles, mumps, rubella, and H. influenzae type B) has decreased substantially or been eliminated entirely in North America. By age six, Ontario children should have received immunization against 12 diseases. Under the Child Care and Early Years Act, children attending childcare settings are required to provide proof of age-appropriate immunization (unless exempt) against: Diphtheria, tetanus, pertussis, polio, Haemophilus influenzae B disease, measles, mumps, rubella, meningococcal disease, pneumococcal disease, and varicella (chickenpox). Rotavirus and influenza vaccination are recommended but not required. Under the Immunization of School Pupils Act, children attending school are required to provide proof of age-appropriate immunization (unless exempt) against: Diphtheria, tetanus, pertussis, polio, measles, mumps, rubella, and meningococcal disease, as well as varicella if born in 2010 or later. Influenza vaccination is recommended but not required. For more information on publicly funded vaccines and the routine immunization schedule, see the Publicly Funded Immunization Schedules for Ontario. 5 5 Because vaccines have different levels of effectiveness and/or do not cover all strains or subtypes of the organisms at which they are aimed, not all vaccines are equally effective. Coverage of the population is also not 100%. This is why it is important to monitor the incidence of vaccine-preventable diseases Halton Region Infectious Disease Report 8

15 In 2017, there were 500 reported cases of VPDs among Halton residents, accounting for 20% of all cases of reportable infectious diseases that year. Figure 3 shows the number of cases of VPDs in Halton residents in 2017 compared to the previous five-year averages. There were no cases of diphtheria, invasive Haemophilis influenzae B disease, polio, rubella, smallpox, tetanus or Hepatitis B reported to the Health Department in Figure 3: Most frequently reported vaccine-preventable diseases compared to previous five-year average, Halton residents, Sources: Integrated Public Health Information System [2017], extracted March 7, Halton Region Infectious Disease Report 9

16 Influenza In the 2017 calendar year, there were 439 reported cases of influenza, accounting for 88% of the reportable vaccine-preventable diseases and 18% of all reportable diseases. Influenza is a highly infectious respiratory illness caused by one of the three types of influenza virus: A, B, or C. Influenza A and B are of higher public health importance, as they are responsible for epidemics. In contrast to the common cold, symptoms of influenza are more sudden in onset and more severe (fever, sore throat, headache, muscle ache, profound fatigue, cough), especially in very young or old, or in individuals with compromised immune systems. In children, nausea, vomiting, and diarrhea are not uncommon. Symptoms usually resolve in five to seven days, however, complications such as pneumonia may develop. Many cases of influenza are not diagnosed or reported to the Halton Region Health Department because infected individuals often do not seek medical attention or, if they do visit a doctor, physicians often do not order laboratory confirmation because it is unnecessary in uncomplicated situations when influenza is known to be circulating. Monitoring influenza is important due to how quickly epidemics can evolve, the widespread morbidity, and the seriousness of complications, notably viral and bacterial pneumonias. Halton age-standardized influenza incidence rates by calendar year have been similar to those of the province (Figure 4). The impact of influenza as well as the rate of clinical testing are highly variable and therefore annual fluctuations above or below the provincial average are not surprising. The number of laboratory-confirmed cases of influenza can be helpful for tracking the timing and severity of the influenza season. However, the number of cases reported likely underestimates the true burden of disease. The MOHLTC changed the influenza testing process this year and less community based testing was done. Patients seen in family practice and walk in clinics were diagnosed and treated based on symptoms and did not receive laboratory testing for influenza. Overall, both Halton and Ontario have seen a significant increase in the age-standardized rate of influenza from Figure 4: Influenza crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, (calendar year). Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 10

17 Streptococcus pneumoniae In 2017, there were 25 reported cases of invasive Streptococcus pneumoniae (invasive pneumococcal disease) in Halton, accounting for 5% of the reportable vaccine-preventable diseases, and 1% of all reportable diseases. There were four deaths among Halton residents who had been diagnosed with Streptococcus pneumoniae. Streptococcus pneumoniae is a bacterial infection that occurs most frequently in infants, young children, and the elderly. Symptoms include high fever, cough, shortness of breath, chest pain, headache, lethargy, vomiting, and irritability, and in serious cases, seizures and meningitis. The disease can occur throughout the year, but is most common in the winter and spring. The pneumococcal conjugate (Pneu-C-13) vaccine is given to infants at two, four, and 12 months of age. As seen in Figure 5, the age-standardized incidence rates of Streptococcus pneumoniae in Halton were quite variable in the past, as would be expected because of the relatively small numbers, but overall there has been a significant decrease from 2008 to In Ontario, there have been no significant trends over time in the age-standardized rate of Streptococcus pneumonia. In 2017, Halton had a significantly lower age-standardized incidence rate of Streptococcus pneumoniae compared to Ontario. Figure 5: Streptococcus pneumoniae crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 11

18 Chickenpox (varicella) In 2017, there were 18 reported cases of chickenpox, accounting for approximately 4% of the reportable vaccine-preventable diseases and less than 1% of all reportable diseases. Chickenpox, or varicella, is an acute, generalized viral disease involving sudden onset of slight fever, and a rash that begins as red spots, followed by small blisters for 3 to 4 days, and then scabs that may leave small scars. This viral infection remains latent and the disease may recur years later as herpes zoster (shingles) in about 15% of older adults, and sometimes in children. The one-dose varicella immunization program was introduced in Ontario in 2004 and was added to the child immunization schedule. The program was expanded in August 2011 to include a second dose to reduce breakthrough infections from waning immunity in individuals who previously received a single dose. Data are provided both at the individual level for laboratory-confirmed reports or those cases resulting in complications or hospitalization, and in aggregate for uncomplicated cases. Reports received from healthcare providers, schools, child care facilities, and parents are included in aggregate counts. Cases that run their course of illness at home, however, are often not reported to the Halton Region Health Department. Physicians may also make a clinical diagnosis of the disease but not report it to the Health Department. Therefore, caution must be taken when interpreting these data as it is subject to significant underreporting. A comparison to Ontario is not available for chickenpox, as Public Health Ontario excludes chickenpox data from the Infectious Disease Query tool since chickenpox is not reliably reported. The limitations of chickenpox reporting have been recognized, and in 2016 the province made revisions to the varicella standard in the Ontario Public Health Standards to improve aggregate data reporting. This revision will also expand case and contact management for all laboratory-confirmed cases Halton Region Infectious Disease Report 12

19 Pertussis (whooping cough) In 2017, there were ten reported cases of pertussis (whooping cough) in Halton, accounting for 2% of reportable vaccine-preventable diseases and less than 1% of all reportable diseases. Pertussis is a bacterial infection that begins with a mild upper respiratory cough that can last one to two weeks, before progressing to a more frequent and severe cough. The cough (which often sounds like a whoop) may be followed by vomiting, and can last for one to two months. During recovery the cough gradually disappears, but can take several weeks to months to do so. Young infants are at the highest risk and often have the most serious complications. Children receive vaccination against pertussis at two, four, six, and 18 months of age, between four to six years, and again between 14 and 16 years. Adults should receive one dose of pertussis-containing vaccine every ten years after their adolescent dose. Receiving the two, four, and six month doses of the pertussis vaccine is most critical to reduce infant mortality and hospitalizations associated with pertussis. Proof of vaccination is required for all children over the age of six to attend school in Ontario, unless an exemption has been obtained. As seen in Figure 6, the age-standardized incidence rates of pertussis in Halton and Ontario declined between 2006 and 2010, and have variable since 2011 in Halton. The peak in pertussis cases in 2012 and 2015 in Ontario were due to outbreaks among under-immunized religious communities in southwestern Ontario. 6 In 2017, Halton had a significantly lower agestandardized incidence rate of pertussis compared to Ontario. Figure 6: Pertussis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 13

20 Mumps In 2017, there were six cases of mumps reported among Halton residents, and 260 cases in all of Ontario. Mumps is a viral infection. Symptoms of mumps include fever, and swelling/tenderness of one or more salivary glands. Inflammation of the parotid gland may also occur, as well as nonspecific respiratory symptoms. Mumps may result in testicular inflammation in males and ovarian inflammation in females, which in rare cases can lead to fertility issues. Mumps infection in the first trimester of pregnancy may result in fetal loss. The measles, mumps, and rubella (MMR) vaccine is given to children at 12 months, and again between the ages of four and six. Proof of vaccination is required for all children over the age of six to attend school in Ontario, unless an exemption has been obtained. As seen in Figure 7, the age-standardized incidence rates of mumps in Halton and Ontario have varied between 2008 and From 2008 to 2013, there was a significant decrease in the age-standardized incidence rate of mumps in Ontario. In 2017, there was no significant difference in the age-standardized incidence rate of mumps between Halton and Ontario. Figure 7: Mumps crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 14

21 Measles In 2017, there was one case of measles reported among a Halton resident, and eight cases in all of Ontario. Measles is a disease caused by the measles virus. Measles has essentially been eliminated in Canada due to mandatory vaccination, however, travel-related cases, or outbreaks among unvaccinated communities, may still occur. Measles begins with a fever, runny nose, cough, drowsiness, and irritable red eyes. Small white spots may appear in the mouth, and a characteristic red, blotchy rash appears on the face and progresses down the body about three to seven days after the onset of symptoms. Measles complications are the most severe in those with malnutrition or immunodeficiency, and in pregnant women. Exposure to measles while pregnant can cause premature labour or miscarriage. The measles, mumps, and rubella (MMR) vaccine is given to children at 12 months, and again between the ages of four and six. Proof of vaccination is required for all children over the age of six to attend school in Ontario, unless an exemption has been obtained. Invasive meningococcal disease In 2017, there was one case of invasive meningococcal disease reported among a Halton resident, and 31 cases in all of Ontario. Invasive meningococcal disease is caused by the bacterium Neisseria meningitides. Invasive meningococcal disease presents most commonly as either meningitis or meningococcemia (meningococcal sepsis or bloodstream infection). Invasive meningococcal disease has a case fatality between 8-15%, and many that survive the disease have long-term complications such as hearing loss, mental impairment, loss of limbs or use of limbs, and scarring. Symptoms typically appear within three to four days of exposure to the bacteria. About 10% of the population carries the bacteria that cause invasive meningococcal disease, but they may not have any symptoms. These individuals can spread the bacteria as long as they are present in their body. The bacteria are spread through direct contact with nose and throat secretions of people infected with the bacteria, and through saliva. People who have close contact with an individual with invasive meningococcal disease can be given antimicrobial chemoprophylaxis within 24 hours to reduce their risk of developing the disease. The Men-C-C vaccine is given to children at 12 months old, and the Men-C-ACYW vaccine is given in grade seven. Proof of vaccination is required for all children to attend school in Ontario, unless an exemption has been obtained Halton Region Infectious Disease Report 15

22 Hepatitis B In 2017, there were no cases of hepatitis B virus reported among Halton residents, and 115 cases in all of Ontario. Over the past ten years ( ) there have been 31 reported cases of hepatitis B in Halton. Most people with acute hepatitis B virus don t experience symptoms, and those that do often experience symptoms similar to hepatitis C infection, including loss of appetite, fatigue, abdominal pain, and fever, as well as jaundice. In rare cases, the active infection can rapidly (within hours or days) develop into severe liver failure, which may result in death. Hepatitis B infection is classified as chronic when the infection lasts longer than six months. Hepatitis B infection is one of the leading causes of liver cancer worldwide. For this report, only acute cases of hepatitis B are included. Important routes of hepatitis B transmission include sexual contact, sharing of personal items such as razors with an infected individual, mother-to-infant transmission, injection drug use, and exposure to contaminated medical equipment. The hepatitis B vaccine is very effective at reducing the risk of hepatitis B infection. Ontario s universal vaccination program provides the hepatitis B vaccine to students in grade seven. Invasive Haemophilus influenzae b disease In 2017, there were no reported cases of invasive Haemophilus influenzae b (Hib) disease in Halton, and seven reported cases in all of Ontario. Over the past ten years ( ) there has only been one reported case of Haemophilus influenzae b (Hib) in Halton. Hib is a bacterial infection, and most commonly manifests as meningitis (swelling of the fluid surrounding the spinal cord and brain). Symptoms often appear suddenly and include fever, vomiting, lethargy, and a stiff neck or back. Children receive vaccination against Hib at two, four, six, and 18 months of age. Children under the age of five are most likely to get Hib. Prior to the introduction of the Hib vaccine in 1998, Hib was the leading cause of bacterial meningitis in young children. Children attending licensed daycare centres are required to show proof of immunization unless exempt Halton Region Infectious Disease Report 16

23 Tetanus There have been no cases of tetanus reported in Halton since In 2017, there were three reported cases in Ontario. Over the past ten years ( ) there has only been one reported case of tetanus in Halton. Tetanus, also referred to as lockjaw, is characterized by painful muscle spasms, followed by stiff abdominal muscles. Death or serious complications can result if not treated. Infection is introduced into the body through a break in the skin (puncture wound, bites, burns, etc.) by an object that has been contaminated with spores from the bacterium Clostridium tetani. Vaccination against tetanus is given to children at two, four, six, and 18 months of age, between four to six years, and again between 14 and 16 years. Adults should receive a booster dose every ten years. Proof of vaccination is required for all children over the age of six to attend school in Ontario, unless an exemption has been obtained. Rubella There have been no cases of rubella reported in Halton since The last reported case of rubella in Ontario was in Cases that occur in Canada are primarily in unimmunized groups, and rubella was declared eliminated from the Americas in Rubella is a viral disease that presents with a rash, fever, headache, malaise, runny nose, and red eyes. The rash begins on the face and usually spreads within 24 hours. Rubella infection in pregnant women can lead to serious complications including congenital rubella infection (see neonatal section), which can result in miscarriage, stillbirth, fetal malformations, and intellectual disabilities. As such, routine screening for rubella susceptibility is recommended among all women of childbearing age. The measles, mumps, and rubella (MMR) vaccine is given to children at 12 months of age, and again between the ages of four and six. Proof of vaccination is required for all children over the age of six to attend school in Ontario, unless an exemption has been obtained. Diphtheria There have been no reported cases of diphtheria in Ontario since Cases still occur worldwide, mostly in developing nations. Diphtheria is an infection caused by the bacterium Corynebacterium diphtheriae. Diphtheria primarily affects the upper respiratory tract, and can also include fever, sore throat, difficulty swallowing, and malaise. Enlarged lymph nodes give the characteristic swollen neck. Diphtheria is spread from person to person through respiratory droplets from coughing or sneezing. Vaccines containing diphtheria are given to children at two, four, six, and 18 months of age, between four to six years, and again between 14 and 16 years. Adults should receive a booster dose every ten years. Proof of vaccination is required for all children over the age of six to attend school in Ontario, unless an exemption has been obtained Halton Region Infectious Disease Report 17

24 Polio Canada was certified as being polio-free since 1994, and the last case was detected in A single case of polio would be considered a public health emergency in Canada. Polio only remains endemic in three countries: Afghanistan, Nigeria, and Pakistan. Polio (poliomyelitis) is caused by poliovirus. Over 90% of polio cases are asymptomatic. In those with symptoms, fever, headache, malaise, nausea, and vomiting can often progress to severe muscle pain, stiffness of the back and neck, and acute flaccid paralysis, which may be permanent. Paralysis of respiratory or swallowing muscles can cause death. Polio primarily affects children under the age of three. Polio vaccine is given to children at two, four, six, and 18 months of age, and again between four to six years. Proof of vaccination is required for all children over the age of six to attend school in Ontario, unless an exemption has been obtained. Smallpox In 1979, the World Health Organization declared smallpox as eradicated worldwide. For this reason, a single case of smallpox anywhere in the world would be considered a global health emergency. Worries of using smallpox as a bioterrorism weapon exist. Smallpox is an acute disease caused by the variola virus. Smallpox results in a sudden onset of fever, malaise, headache, and severe backache. This is followed 2-4 days later by characteristic skin eruptions, which eventually scab and fall off 3-4 weeks later. Smallpox is not known to have any other reservoir than humans, and due to its eradication, immunization among the general public is not required. Individuals who have contact with the laboratory contained virus are vaccinated against smallpox Halton Region Infectious Disease Report 18

25 Food- and water-borne diseases This section provides an overview of food-borne and water-borne diseases reported to the Health Department in Food-borne and water-borne diseases are caused by bacteria, parasites, and viruses that have found their way into food or water that is being consumed. Food can become contaminated by any number of sources, including infected humans or animals, as well as run-off from landfills, agricultural lands, or sewers. Because the route of exposure to food-borne and water-borne diseases is by ingestion, and because symptoms are usually related to the digestive tract, these diseases are also often referred to as enteric diseases meaning that they are related to the intestine. Many of these diseases can also be transmitted from person-to-person. These diseases may cause nausea, vomiting, abdominal pain, diarrhoea, bloody stools, fever, and severe systemic illness. Illnesses caused by toxins (e.g., from Staphylococcus aureus) or other toxic agents can also be spread by food and water. In 2017, there were 392 reported cases of food and water-borne diseases among Halton residents, accounting for 16% of the total cases of reportable infectious diseases that year. Figure 8 shows the number of cases of the most common food-borne and water-borne diseases in Halton residents in 2017 compared to the previous five-year average. There were no cases of typhoid fever, botulism, cholera, or paralytic shellfish poisoning reported among Halton residents in Food and water-borne diseases are the most common type of travel-related illness, typically acquired from improperly prepared foods or untreated water in countries that do not have food safety standards equivalent to Canada. In 2017, 41% of reported cases of food- and waterborne illness with known risk factors/exposures in Halton were associated with travel outside of Canada. Figure 8: Most frequently reported food- and water-borne diseases compared to previous five-year average, Halton residents, Sources: Integrated Public Health Information System [ ], extracted March 7, Halton Region Infectious Disease Report 19

26 Campylobacter enteritis In 2017, there were 152 reported cases of Campylobacter enteritis in Halton, accounting for 39% of the reportable food- and water-borne diseases, and 6% of all reportable diseases. Campylobacter enteritis is a bacterial disease most often caused by the bacterium Campylobacter jejuni, and less commonly Campylobacter coli. Animals most frequently poultry and cattle are the reservoirs of Campylobacter organisms. The most common mode of transmission of this disease is through ingestion of the organisms in undercooked meat, contaminated food or water, or unpasteurized milk. Person-to-person transmission is possible, but uncommon. Typical symptoms of Campylobacter enteritis can include diarrhoea (which may be bloody), abdominal pain, fever, nausea, vomiting, and malaise. Symptoms usually occur within two to five days of becoming infected with the bacteria, and may last for one or two weeks. Reported age-standardized incidence rates of Campylobacter enteritis in Halton and Ontario have fluctuated over the past ten years (Figure 9). In 2017, there was no significant difference in the age-standardized incidence rate of Campylobacter enteritis between Halton and Ontario. Figure 9: Campylobacter enteritis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 20

27 Salmonellosis In 2017, there were 114 reported cases of salmonellosis in Halton, accounting for 29% of the reportable food- and water-borne diseases, and 5% of all reportable diseases. Salmonellosis is classified as a food-borne disease because contaminated food, mainly of animal origin, is the predominant mode of transmission. Symptoms of salmonellosis include abdominal pain, diarrhoea, vomiting, and fever. Symptoms generally present within six to 72 hours of ingesting contaminated food or water, and typically last four to seven days. As seen in Figure 10, the age-standardized incidence rate of salmonellosis reported in Halton has fluctuated over time, similar to Ontario, with a general upwards trend. From 2008 to 2017, there was a significant increase in the age-standardized incidence rate of salmonellosis in Halton and Ontario. In 2017, there was no significant difference in the age-standardized incidence rate of salmonellosis between Halton and Ontario. Figure 10: Salmonellosis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 21

28 Giardiasis In 2017, there were 45 reported cases of giardiasis in Halton, accounting for 11% of the reportable food- and water-borne diseases, and 2% of all reportable diseases. Reservoirs of giardiasis include humans, and possibly other wild and domestic animals such as the beaver. Giardiasis can be transmitted through food or water contaminated with the protozoan giardia parasite. Person-to-person transmission can occur by hand-to-mouth transfer of cysts from the faeces of an infected individual. This mode of transmission is especially common in institutions and day care centres. Giardiasis primarily affects the upper small intestine. Giardiasis can affect people in different ways, ranging from no symptoms, to acute, self-limiting diarrhoea, or it may lead to intestinal symptoms such as chronic diarrhoea, abdominal cramps, bloating, fatigue, and weight loss. It can also negatively affect the body s ability to absorb fats and fat-soluble vitamins. Symptoms typically present within one to three weeks of exposure to the giardia parasite. Similar to other food and water-borne diseases, age-standardized rates of giardiasis in Halton have varied over the past ten years. The decline in the incidence of giardiasis in both Halton and Ontario from 2008 to 2017 was statistically significant (Figure 11). In 2017, there was no statistically significant difference in the age-standardized rate of giardiasis between Halton and Ontario. Figure 11: Giardiasis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 22

29 Amebiasis In 2017, there were 14 reported cases of amebiasis in Halton, accounting for 4% of the reportable food- and water-borne diseases, and less than 1% of all reportable diseases. Amebiasis is an infection of the intestines caused by the parasite Entamoeba histolytica. The infection is spread through food or water that has been contaminated by infected faeces. It can also be spread from person-to-person. Many people with amebiasis do not have any symptoms. If symptoms do occur, they typically appear between two to four weeks of being exposed to the parasite, however, can range anywhere from a few days to years. Symptoms may include abdominal cramps, diarrhoea, and fatigue. In severe cases, fever, vomiting, and bloody stools may also occur. Age-standardized rates of amebiasis have remained fairly constant in Ontario over the past ten years, with a slight downward trend, but have varied from year to year in Halton (Figure 12). Over the past ten years, the age-standardized rate of amebiasis has been lower in Halton than Ontario, and for 2017, this difference was statistically significant. Figure 12: Amebiasis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 23

30 Cyclosporiasis In 2017, there were 13 reported cases of cyclosporiasis in Halton, accounting for 3% of the reportable food- and water-borne diseases, and less than 1% of all reportable diseases. Cyclosporiasis is an intestinal infection caused by the parasite Cyclospora cayetanensis. The infection is spread through food or water that has been contaminated by faeces infected with the parasite. Diarrhoea is a typical symptom of cyclosporiasis, and other common symptoms include loss of appetite, stomach pain, nausea, and fatigue. Vomiting, fever, and flu-like symptoms may also be present. Symptoms typically begin within one week of becoming infected with the parasite, however not all people experience symptoms. Age-standardized rates of cyclosporiasis have increased in Halton and Ontario between 2008 and 2017, with a steeper increase from 2012 to Cyclosporiasis is not endemic in Canada and outbreaks are often associated with consumption of contaminated food from endemic countries, or travel to countries where it is endemic. The increase in 2015 was likely due to three outbreaks, both travel- and non-travel related. One outbreak was linked to the consumption of sugar snap peas; another was linked to travel to Mexico; and the source was never identified for the third outbreak. 7 In 2017, Halton had a slightly higher age-standardized rate of cyclosporiasis compared to Ontario, however this difference was not statistically significant (Figure 13). Figure 13: Cyclosporiasis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 24

31 Yersiniosis In 2017, there were 13 reported cases of yersiniosis in Halton, accounting for approximately 3% of the reportable food- and water-borne diseases, and less than 1% of all reportable diseases. Yersiniosis is caused by consumption of food or water contaminated with Yersinia bacteria, or through person-to-person contact with an infected individual. One of the most common sources of the bacteria is raw or undercooked pork, as well as other meats, fish, and milk. Symptoms of yersiniosis differ depending on age. Children often experience fever, abdominal pain, and diarrhea, while older children and adults typically experience fever and abdominal pain on their right side. Symptoms of yersiniosis usually appear within three to seven days of becoming infected, and can last for two to three weeks. In Ontario, age-standardized incidence rates of yersiniosis were decreasing between 2008 and 2014, but increased from 2015 to This increase does not appear to be outbreak-related. Rates in Halton have been variable over the past ten years, which is expected due to the small number of cases (Figure 14). In 2017, there was no statistically significant difference in the agestandardized rate of yersiniosis in Halton compared to Ontario. Figure 14: Yersiniosis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 25

32 Cryptosporidiosis In 2017, there were 13 reported cases of cryptosporidiosis in Halton, accounting for approximately 3% of the reportable food- and water-borne diseases, and less than 1% of all reportable diseases. Cryptosporidiosis (often referred to as crypto ) is a disease caused by the parasite Cryptosporidium. Cryptosporidium is transmitted through the faecal-oral route, often via contaminated water. The most common symptoms of cryptosporidiosis include watery diarrhoea, abdominal pain, and cramping, although not all people infected with the parasite experience any signs or symptoms. For people with weakened immune systems, such as individuals with HIV/AIDS, cryptosporidiosis can be life-threatening. Symptoms of cryptosporidiosis begin on average one week after infection with the parasite, and can last for a month or less in healthy individuals, or longer for those who are immunocompromised. Age-standardized rates of cryptosporidiosis in Halton have varied from year to year, which is expected due to the small number of cases. Ontario has also had no significant trends (Figure 15). Over the past ten years, the age-standardized rate of cryptosporidiosis has been lower in Halton than Ontario, however this difference was not statistically significant in Figure 15: Cryptosporidiosis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 26

33 Shigellosis In 2017, there were ten reported cases of shigellosis in Halton, accounting for 3% of the reportable food- and water-borne diseases, and less than 1% of all reportable diseases. Shigellosis is an infectious disease of the intestines caused by the Shigella bacteria. Shigellosis is spread through direct or indirect fecal-oral contact, including eating food or water contaminated with Shigella bacteria. Symptoms of shigellosis include fever, diarrhoea (which may be bloody), nausea, and vomiting. Symptoms typically begin within one to three days after exposure to the bacteria, and illness typically lasts for four to seven days. People who are infected with the Shigella bacteria can continue to be infectious for four weeks after the illness. Some people can be infected with the bacteria and not show any symptoms, but still spread the infection to others. Similar to other food and water-borne illnesses, shigellosis cases in Halton are often travel-related. Age-standardized rates of shigellosis have varied over the past ten years in Halton, and have shown a slight but significant upward trend in Ontario (Figure 16). The increase in Ontario in 2016 was due to an increase in cases among men aged with anal-oral contact as a risk factor. The increase in Halton in 2016 was largely due to travel related cases and unknown risk factors. Over the past ten years, the age-standardized rate of shigellosis has been similar in Halton and Ontario. In 2017, there was no statistically significant difference in the agestandardized rate of Shigellosis between Halton and Ontario. Figure 16: Shigellosis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 27

34 Legionellosis In 2017, there were eight reported cases of legionellosis among Halton residents, accounting for approximately 2% of food- and water-borne illnesses reported in Halton. Legionellosis consists of two respiratory illnesses caused by Legionella bacteria. The bacteria are found in warm water, such as water from hot tubs, hot water tanks, and plumbing systems. People can become exposed to Legionella bacteria if they breathe in mist or vapour contaminated with the bacteria. If the respiratory infection caused by the Legionella bacteria is severe and causes pneumonia, it is referred to as Legionnaires disease. Other symptoms include cough, headache, malaise, loss of appetite, and fever. Symptoms typically begin within two weeks of being exposed to the bacteria, and can last several months. Legionnaires disease is a relatively uncommon disease, as fewer than 5% of people who are exposed to the bacteria actually develop the disease. Pontiac fever is a milder illness caused by Legionella, which has flu-like symptoms without pneumonia. Symptoms of Pontiac fever typically begin within hours, and usually resolve within a few days without treatment. Age-standardized rates of legionellosis varied from year to year in Halton and Ontario, which is expected due to the small number of cases (Figure 17). In 2017, the age-standardized rates of reported cases of legionellosis were similar in Halton and Ontario. Figure 17: Legionellosis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 28

35 Verotoxin-producing E. coli with haemolytic uraemic syndrome In 2017, there were five reported cases of verotoxin-producing E. coli with haemolytic uraemic syndrome, accounting for about 1% of food- and water-borne illnesses reported in Halton. Verotoxin-producing E. coli is a group of bacteria, which is often found in animals such as cattle, sheep, pigs, and goats, and can cause illness in humans. It is spread by ingesting contaminated food or water, as well as person-to-person via the fecal-oral route. Some sources of exposure to verotoxin-producing E. coli include raw or undercooked ground beef, raw fruits and vegetables, and unpasteurized milk and juice. Symptoms of Verotoxin-producing E. coli typically appear three to four days after exposure to the pathogen, and may include stomach cramps, malaise, vomiting, and diarrhoea (which can be bloody). In some cases, a serious complication involving the kidneys can occur, called haemolytic uraemic syndrome (HUS), which may lead to life-threatening kidney failure. Young children are particularly at risk of developing HUS, as well as older adults. Age-standardized rates of verotoxin-producing E. coli have varied from year to year in Ontario and Halton, which is expected due to the small number of cases (Figure 18). In 2017, the agestandardized rates of verotoxin-producing E. coli with HUS were similar between Halton and Ontario. Figure 18: Verotoxin-producing E. coli crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 29

36 Hepatitis A In 2017, there were two reported cases of Hepatitis A in Halton, and 126 cases in all of Ontario. Hepatitis A is a viral infection of the liver that is spread through food or water contaminated with the faeces of an infected person, or through close contact with an infected person. Common sources include uncooked food, such as shellfish and produce. Symptoms of Hepatitis A can include fever, loss of appetite, abdominal discomfort, jaundice, dark colored urine, and light coloured stools. The time between exposure to the virus and onset of symptoms is variable, but on average takes about one month. Hepatitis A is one of the most common vaccine-preventable diseases among travellers. Hepatitis A is common in areas with poor sanitation, with a higher risk among travellers to Africa, Asia, and Central and South America. The Hepatitis A vaccine is recommended for travelers to high-risk areas, as well as various other high-risk groups. An initial dose of the vaccine is given, followed by a booster dose six months to three years later, depending on the type of vaccine. Listeriosis In 2017, there were two reported cases of listeriosis in Halton, and 55 cases in all of Ontario. Listeriosis is a disease that occurs when people eat or drink food or beverages contaminated with the bacteria Listeria monocytogenes. Common sources of Listeria include ready-to-eat meats, unpasteurized milk and cheeses, as well as raw vegetables. Symptoms of listeriosis include nausea, vomiting, muscle aches and cramps, diarrhea, and fever. In serious cases, the infection can spread to the nervous system and cause meningoencephalitis (brain infection), septicemia (blood poisoning), endocarditis (infection of the lining of the heart), and death. Listeriosis can cause serious complications in pregnant women including miscarriage, preterm labour, stillbirth, or meningitis in newborns. The length of time between infection and onset of symptoms, as well as the length of the illness, is variable. Paratyphoid fever In 2017, there was one reported case of paratyphoid fever in Halton, and 34 cases in all of Ontario. Paratyphoid fever is a disease caused by several strains of the bacteria Salmonella enterica. Paratyphoid fever is not known to be endemic in Ontario, and cases are almost always travelacquired from other areas of the world such as South and South-East Asia. Paratyphoid fever is transmitted via the faecal-oral route, including ingestion of food and water contaminated by the faeces of infected individuals. Common sources include contaminated milk, raw fruit and vegetables, and shellfish. Symptoms of paratyphoid fever take one to ten days to appear after exposure to the bacteria, and include fever, headache, malaise, loss of appetite, and a decrease in bowel movements. Symptoms can also include decreased heart rate, enlargement of the spleen, and rose coloured spots on the chest Halton Region Infectious Disease Report 30

37 Typhoid fever In 2017, there were no reported cases of typhoid fever in Halton, and 105 cases in all of Ontario. Typhoid fever is an infection caused by the bacteria Salmonella typhi. Typhoid fever is transmitted via the faecal-oral route, most often through eating food or water contaminated by infected human faeces. Cases of typhoid fever in Canada are typically acquired abroad, with the highest risk being among travellers to South Asia. Symptoms of typhoid fever are variable and may include fever, headache, malaise, cough, nausea, abdominal pain, and loss of appetite, and typically occur within one to two weeks of becoming infected. In severe cases, typhoid fever can cause delirium and confusion. Some people with fair skin also develop rose colored spots on their torso. In Canada, typhoid immunization is available and recommended for most people travelling to South Asia. Botulism In 2017, there were no reported cases of botulism in Halton or Ontario. The last reported case of botulism in Halton was in 2012, and 2015 in Ontario. Foodborne botulism is caused by ingesting toxins produced by the bacteria Clostridium botulinum in contaminated food. Common sources of botulism include canned foods, home preserved foods, and smoked or salted fish. Other types of botulism include wound botulism, which occurs when a wound is contaminated by C. botulinum (most often among injection drug users), and infant botulism, which is caused by ingesting spores of the botulinum bacteria, which grows and releases toxins in the intestines. Symptoms of botulism include fatigue, weakness, vertigo, blurred vision, difficulty speaking, and dry mouth. Symptoms may progress to paralysis and in rare cases, death. In foodborne botulism, symptoms typically begin within 12 to 36 hours of consuming the toxin, whereas with wound botulism it may take up to two weeks for symptoms to occur. In Ontario, a single case of foodborne botulism or wound botulism should be treated as an outbreak, whereas two cases of infant botulism should be investigated as an outbreak. Cholera In 2017, there were no cases of cholera reported in Halton, and five cases in all of Ontario. The last reported case of cholera in Halton was in Cholera is caused by toxin-producing strains of the bacteria Vibrio cholerae. Cholera is transmitted by consuming food or water contaminated by vomit or faeces infected with V. cholera. Cholera is not endemic to Canada, and cases are associated with travel to areas of the world where it is endemic. Symptoms of cholera typically include diarrhoea and vomiting, however most people infected with V. cholerae do not experience any symptoms. Severe cases can result in dehydration and death. Symptoms typically begin within a few hours to 5 days of becoming infected with V. cholerae Halton Region Infectious Disease Report 31

38 Trichinosis In 2017, there were no reported cases of trichinosis in Halton, and two cases in all of Ontario. Trichinosis is a food-borne illness found worldwide. It is caused by the intestinal roundworm Trichinella, and is typically acquired from eating infected pork or meat from wild animals. After humans eat meat infected with Trichinella larvae, the larvae grow into adult worms and reproduce. Initial symptoms may include abdominal pain, nausea, vomiting, or diarrhea. Within a few weeks of consuming the infected meat, the larvae then travel through tissues in the body including muscle, and symptoms may include muscle pain, fever, weakness, headache, conjunctivitis, and bleeding under the nails. Risk of trichinosis can be reduced by implementing food safety procedures such as cooking meat to a sufficient internal temperature. Paralytic shellfish poisoning In 2017, there were no cases of paralytic shellfish poisoning in Halton or Ontario. There has only been one reported case of paralytic shellfish poisoning in Ontario (in 2014) since it became a reportable disease in September Paralytic shellfish poisoning is caused by neurotoxins present in shellfish that are produced by phytoplankton or dinoflagellates in the ocean. Symptoms of paralytic shellfish poisoning typically begin within 30 minutes to three hours of ingesting the toxin, and include tingling or numbness, dizziness, vomiting, headache, paralysis of the arms and legs, lack of balance and coordination, as well as incoherent speech. In severe cases it can lead to respiratory failure and death. The Canadian Food Inspection Agency is responsible for monitoring water quality in areas where shellfish are harvested, as well as testing for paralytic shellfish poisoning Halton Region Infectious Disease Report 32

39 Sexually-transmitted and blood-borne infections This section provides an overview of the sexually-transmitted infections (STIs) and blood-borne infections reported to the Health Department in Reportable STIs include a number of viral and bacterial infections that are primarily transmitted through oral, vaginal, and/or anal intercourse. Other terms for STIs include sexually-transmitted diseases (STDs), and venereal diseases. Blood-borne infectious diseases are spread primarily through blood-to-blood contact. People who are at higher risk for blood-borne infectious diseases include injection drug users, and healthcare workers or workers in other occupations who may be exposed to needle-stick or other sharps injuries. While blood transfusions could also be a source of blood-borne infectious disease, the risk of transmission of infectious diseases through blood in Canada is low due to effective donor screening and laboratory tests. In 2017, there were 1479 reported sexually-transmitted and blood-borne infections in Halton, accounting for over half (60%) of all reportable diseases. Figure 19 shows the reported number of cases of sexually-transmitted and blood-borne infections among Halton residents in 2017 compared to the previous five-year averages. There were no cases of chancroid reported in Halton in Figure 19: Most frequently reported sexually-transmitted and blood-borne infections in Halton compared to previous five-year average, Halton residents, Sources: Integrated Public Health Information System [ ], extracted March 7, *Excludes early congenital syphilis 2017 Halton Region Infectious Disease Report 33

40 Chlamydia In 2017, there were 1148 reported cases of chlamydia in Halton, accounting for 78% of all reportable sexually-transmitted and blood-borne infections and 46% of all reportable diseases. Chlamydia is a STI caused by the bacterium Chlamydia trachomatis, and it is the most common sexually-transmitted infection reported in Halton and Ontario. In men, symptoms of chlamydia include discharge from the penis, pain or discomfort when urinating, and redness, itching, and swelling of the urethra. In females, chlamydia may present as a cervical infection with pain or bleeding during sexual intercourse, bleeding between periods, and discomfort when urinating. The majority of females with chlamydia however do not experience any symptoms. This infection is therefore likely to be underreported. In 2017, the age-standardized incidence rate of chlamydia in Halton was significantly lower than Ontario (Figure 20). The age-standardized incidence rate of chlamydia in Halton increased by 41% between 2008 and 2017, from 118 cases per 100,000 to 201 cases per 100,000 (Figure 20). This is consistent with a general rise in chlamydia rates seen in Ontario over the past ten years. Some of the increase in chlamydia rates throughout the province can be attributed to improved quality and acceptability of screening and testing methods. However, chlamydia continues to be considered a hidden epidemic due to lack of awareness about the problem, and because the majority of cases do not have any symptoms but are still infectious. Awarenessraising initiatives around the importance of safer sex practice (particularly condom use) and STI testing continue to be important components of health promotion campaigns concerning chlamydia and other STIs. Figure 20: Chlamydia crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 34

41 Similar to Ontario, the majority of chlamydia cases in Halton in 2017 were youth and young adults. Halton females aged and were significantly more likely than males in the same age groups to have reported cases of chlamydia (Figure 21). The higher rate of chlamydia among females may be related to a larger number of women being screened for this infection compared to men. Figure 21: Chlamydia age-specific incidence rates (per 100,000), by sex, Halton residents, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Halton Region Infectious Disease Report 35

42 Gonorrhoea In 2017, there were 179 reported cases of gonorrhoea infection in Halton, accounting for 12% of all reportable sexually-transmitted and blood-borne infections and 7% of all reportable infectious diseases in Halton. Gonorrhoea is a sexually-transmitted bacterial infection, which differs in males and females in course, severity, and ease of recognition. Worldwide, this infection affects both men and women, especially sexually active adolescents and younger adults. Untreated individuals may be infectious for months. The age-standardized incidence rate of gonorrhoea was relatively stable between 2007 and 2013, however, both Halton and Ontario have seen significant increases in rates since 2014 (Figure 22). The age-standardized incidence rate of gonorrhoea in Halton continues to be significantly lower than in Ontario. Public Health Ontario has been monitoring this increase provincially and has reported that it is not fully understood and likely multifactorial. 8 In particular they are examining antibiotic sensitivity and adherence to treatment and testing guidelines, and have undertaken an 9, 10 evaluation of Ontario s provincial treatment guidelines. Figure 22: Gonorrhoea crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 36

43 Similar to Ontario, the majority of gonorrhoea cases in Halton were in youth and young adults. Overall, males in Halton had higher rates of reported gonorrhoea compared to females (Figure 23). This higher rate of gonorrhoea in males compared to females is likely due to more males seeking treatment for gonorrhoea symptoms, as most women with gonorrhoea do not experience any symptoms or they may only experience mild symptoms. Figure 23: Gonorrhoea age-specific incidence rates (per 100,000), by sex, Halton residents, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Halton Region Infectious Disease Report 37

44 Hepatitis C In 2017, there were 102 reported cases of hepatitis C virus infection among Halton residents, accounting for 7% of reportable sexually-transmitted and blood-borne infections, and about 4% of all reportable diseases in Halton. Symptoms of hepatitis C infection are typically mild, and may include loss of appetite, abdominal discomfort, fatigue, nausea and vomiting. Many people do not experience any symptoms. Between 50-80% of those infected with the hepatitis C virus will develop chronic infection, which may lead to liver damage (cirrhosis), liver cancer, or liver failure. Hepatitis C is primarily spread by blood-to-blood contact, with sharing needles being one of the highest risk factors for infection. While the risk is low, it is also possible to acquire the infection from unprotected sex with an infected individual if there is blood-to-blood contact. Mother-tochild transmission has also been documented, but it is rare. Important interventions to reduce the risk of hepatitis C include harm reduction strategies such as needle exchange programs, as well as infection control procedures in healthcare settings to reduce the risk of exposure for healthcare workers. The age-standardized rate of hepatitis C in Halton has declined in recent years, from 28 per 100,000 in 2008 to 18 per 100,000 in 2017 (Figure 24). The age-standardized rate of hepatitis C in Ontario also declined slightly during the same time period. In 2017, the age-standardized rate of hepatitis C was significantly lower in Halton compared to Ontario. However, it is important to consider when interpreting reported hepatitis C rates over time that most cases are reported months or years following infection. Figure 24: Hepatitis C crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 38

45 Syphilis In 2017, there were 35 reported cases of syphilis: 17 infectious and 18 other (non-infectious or unspecified) cases in Halton, accounting for 2% of reportable sexually-transmitted and bloodborne infections. Syphilis is a complex sexually-transmitted bacterial infection with four stages. Primary syphilis is characterized clinically by a primary lesion called a chancre (painless ulcer). Secondary syphilis is characterized by a rash that typically appears on the palms of hands and soles of feet and/or mucous membrane lesions in the mouth, vagina, or anus. At this stage, fever and malaise may also be present. The latent stage of syphilis begins when the symptoms of the previous stages disappear. Untreated latent syphilis can progress to tertiary syphilis, which can involve cardiovascular and neurological complications and may lead to death. Primary, secondary, and early latent syphilis are considered infectious, while late latent and tertiary syphilis are considered non-infectious. Syphilis can also be passed from an infected mother to an unborn infant through the placenta, or at the time of birth (see Early congenital syphilis). The age-standardized rate of syphilis was slowly decreasing in Ontario until 2013, and has been increasing since 2014, while rates have fluctuated in Halton over the past ten years (Figure 25). In 2017, the age-standardized rate of syphilis in Halton was significantly lower than Ontario. Newly diagnosed non-infectious syphilis cases are found primarily through screening and the higher rates of non-infectious disease may reflect increased screening. While cases of noninfectious syphilis may have actually been acquired years before they are diagnosed and reported, they are still counted as incident cases in the year of diagnosis. Figure 25: Syphilis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 39

46 HIV and AIDS In 2017, there were 13 reported cases of HIV in Halton, accounting for 1% of reportable sexually-transmitted and blood-borne infections, and two reported case of AIDS. AIDS is a chronic condition and may span many years from diagnosis (with HIV) to death. Human Immunodeficiency Virus (HIV) is a virus that targets the body s immune system. Symptoms of HIV infection are variable and may include mild flu-like symptoms such as fever, sore throat, headaches, and swollen lymph nodes. Left untreated, the infection progressively interferes with the body s immune system. HIV infection becomes Acquired Immune Deficiency Syndrome (AIDS) when the immune system is severely weakened (as measured by CD4 cell count), or when a person develops one or more opportunistic infections. Most people with AIDS die from an infection, cancer, or other disease that they were more susceptible to because of their weakened immune systems. The prognosis for people with HIV has improved immensely in recent decades. With treatment, HIV is a manageable disease and many people with the infection can live long lives. HIV is transmitted from person to person through unprotected sexual intercourse, blood, breast milk, and contact with sexual bodily fluids. It can also be transmitted from mother to child. The period in which a person with HIV can spread the infection on to others is not precisely known, however people are most infectious during the first months of infection, when they have other STIs present, and when they have a high viral load. Certain population groups that tend to have a higher risk of acquiring HIV include men who have sex with men and injection drug users. There was a general decrease in the age-standardized rate of HIV in Ontario from 2008 to 2013, but the rate has since been variable from 2014 to Rates in Halton have been variable over the past ten years, which is expected due to the small number of cases (Figure 26). In 2017, Halton s age-standardized rate of HIV was significantly lower than Ontario. Figure 26: HIV crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 40

47 Chancroid Chancroid is very rare in North America, and there have been no reported cases of chancroid in Ontario since Chancroid is most common in tropical and subtropical regions of the world. Chancroid is a bacterial infection caused by Haemophilus ducreyi. Chancroid is characterized by a single or multiple open, painful sores on the genitals. It is transmitted by direct sexual contact with the open sores. People with chancroid can spread the infection to others until the sores are healed, which can take anywhere from weeks to months without treatment, or one to two weeks with antibiotic treatment Halton Region Infectious Disease Report 41

48 Neonatal infectious diseases In 2017, there were only two cases of a reportable neonatal disease: neonatal group B streptococcal disease. Reportable neonatal diseases are those that are transferred from mother to infant either through the placenta or through the birth canal at the time of delivery. Neonatal group B streptococcal disease In 2017, there were two reported cases of neonatal group B streptococcal disease in Halton, and 52 cases in all of Ontario. Approximately 10-30% of pregnant women have group B streptococci bacteria in their genital tract. The bacteria can be passed from the mother to her infant in utero or through the birth canal in early onset transmission, or through person-to-person contact with late onset transmission. Infection with the bacteria can be life-threatening in infants, and cause septicemia (blood infection), pneumonia, or meningitis. The risk of neonatal group B streptococcal disease is greatly reduced through prenatal screening for group B streptococci. Antibiotic treatment can prevent the spread of the bacteria from mother-to-child. Proper hand-washing procedures can also help reduce the spread of the bacteria once the infant is born. Early congenital syphilis There were no cases of early congenital syphilis reported in Halton in 2017, and one case in all of Ontario. Congenital syphilis is a life-threatening infection in infants, contracted from an infected mother through the placenta or at the time of birth. Congenital syphilis can result in stillbirth, pre-term birth, or other serious complications. Screening for syphilis is recommended as a routine prenatal test. Treatment of infected mothers for syphilis lowers the risk to the infant. Congenital rubella syndrome In 2017, there were no reported cases of congenital rubella syndrome in Halton or Ontario. The last reported case of congenital rubella syndrome in Ontario was in Congenital rubella syndrome occurs when a pregnant mother infected with rubella virus passes the virus to their infant. Risk of fetal infection is particularly high during the first trimester of pregnancy. Congenital rubella syndrome can result in miscarriage, stillbirth, and numerous other complications such as deafness, intellectual disabilities, and congenital heart disease. Some infants with congenital rubella syndrome may appear healthy at birth, but later develop eye, ear, or brain damage. As the rubella virus is not endemic in Canada, a single case of congenital rubella syndrome would be considered an outbreak. Vaccination against rubella (using the MMR vaccine) prior to pregnancy is important to prevent pregnant mothers from becoming infected with rubella and passing it onto their unborn infants Halton Region Infectious Disease Report 42

49 Opthalmia neonatorum There were no cases of opthalmia neonatorum in Halton in 2017, and three cases in all of Ontario. Opthalmia neonatorum is a serious eye infection that can occur when either Neisseria gonorrhoeae (the bacterium that causes gonorrhoea) or Chlamydia trachomatis (the bacterium that causes chlamydia) is passed from an infected mother to her infant during birth. Symptoms of opthalmia neonatorum include swollen red eyelids and discharge from the eyes, and typically occur within three weeks of birth. Under the Health Protection and Promotion Act, it is required that new-born babies are treated with an eye drop solution that destroys any infectious bacteria that might cause opthalmia neonatorum Halton Region Infectious Disease Report 43

50 Zoonotic, vector-borne, and exotic diseases This section provides an overview of zoonotic, vector-borne, and exotic infectious diseases. Zoonotic diseases are diseases that can be passed from animals to humans. Vector-borne diseases are spread to people by small organisms like mosquitos and ticks. Exotic diseases refer to other diseases that are not normally found in Ontario and Halton. In 2017, there were 26 cases (all vector-borne) reported in Halton, accounting for approximately 1% of all reportable diseases. Figure 27 shows the reported number of cases of these vectorborne infections among Halton residents in 2017 compared to the previous five-year averages. There were no cases of any of the other 12 reportable zoonotic, exotic, or vector-borne infectious diseases in Halton in Figure 27: Most frequently reported zoonotic and exotic infections in Halton compared to previous five-year average, Halton residents, Sources: Integrated Public Health Information System [ ], extracted March 7, Halton Region Infectious Disease Report 44

51 Lyme disease In 2017, there were 13 reported cases of Lyme disease in Halton. Of these 13 cases, eight were associated with travel to risk areas within Ontario, one was associated with travel outside of Ontario, and four were associated with travel outside of Canada. Lyme disease is a zoonotic disease caused by the bacterium Borrelia burgdorferi. The bacteria are spread through the bite of an infected blacklegged tick. Lyme disease occurrence varies with the season, and is more common in the summer due to increased activity outdoors and the higher presence of infectious ticks in the environment. There are three stages of Lyme disease. In the early localized stage, infected individuals may experience the characteristic bulls eye rash at the site of the tick bite, as well as fever, stiff neck, headache, and muscle and joint pain. In the early disseminated stage, neurological problems may begin, such as twitching of the facial muscles or facial paralysis, meningitis, fatigue, and muscle and joint pain. Late stages of the disease may involve further problems with the heart, nervous system, and joints, including arthritis, meningitis, and behavioural changes. Most cases of Lyme disease can be treated with antibiotics. Taking steps to avoid tick bites, such as wearing insect repellent and clothes that cover the body, can help reduce the risk of Lyme disease. Halton residents who find a tick on themselves or family members can submit ticks to the Halton Region Health Department for identification and testing. In 2017, the age-standardized rate of Lyme disease in Halton was significantly lower than Ontario. The age-standardized rate of Lyme disease has been on the rise over the past ten years, and both Halton has seen a steep increase in 2017 (Error! No bookmark name given.). This is likely due to several factors: the risk areas where Borrelia burgdorferi-infected blacklegged ticks are found are expanding, but there is also an increased awareness of Lyme disease by the public and physicians, resulting in an increase in testing. 10 Figure 28: Lyme disease crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 45

52 Malaria In 2017, there were seven reported cases of malaria in Halton Region, and 215 cases in Ontario. Malaria is a disease caused by parasites from the Plasmodium genus, and is transmitted through the bite of a female Anopheles mosquito. Malaria is a major cause of illness in tropical areas throughout Africa, Asia, Central and South America. Malaria is not endemic to Ontario, and therefore reported cases in Halton are due to travel-acquired infections or acquired prior to immigrating to Canada from a country where malaria is endemic. Common symptoms of malaria include fever, chills, sweats, and headache. Complications of malaria can include coma, as well as liver, kidney, and other organ failure, which can result in death. With certain types of malaria infection, relapses of the disease may occur. The incubation period for malaria is variable depending on the Plasmodium species they are infected with, and can range from weeks to months. Personal protection against insect bites and vector control are important preventative measures for malaria. West Nile virus illness In 2017, there were six reported cases of West Nile virus in Halton, and 159 cases in total throughout all of Ontario. West Nile virus is a Flavivirus that is most commonly transmitted to humans via mosquitos in the genus Culex. Birds are the primary reservoir for West Nile virus (site where the virus normally lives and replicates). West Nile virus was first reported in Uganda in the 1930s, and first appeared in Ontario in The majority of West Nile virus infections occur in Ontario during the summer months, and incidence rates fluctuate due to differences in weather and the size of the mosquito population from year to year. Most people who are infected with West Nile virus do not have any symptoms. For those that do experience symptoms, symptoms typically appear within two to 15 days of becoming infected with the virus. Mild cases of West Nile virus may experience a flu-like illness, including fever, headache, body ache, and skin rash. In serious cases, neurological complications may occur, including encephalitis and meningitis. Q fever In 2017, there were no reported cases of Q fever in Halton, and 13 reported cases in all of Ontario. The last reported case of Q fever in Halton was in Q fever is caused by the bacterium Coxiella burnetii. Reservoirs of the bacteria include cattle, goats, sheep, dogs, and cats, as well as several wild animals. Coxiella burnetii is shed by infected animals in their urine, feces, milk, and in the amniotic fluids and placenta during birth. Humans can become infected by inhaling dust particles that are contaminated by the infected animals. People who spend time with animals, such as farmers and veterinarians, are at highest risk for the disease. There is also concern that this Coxiella burnetii could be used for bioterrorism, as it is resistant to many disinfectants, and can become airborne and cause disease in humans when inhaled Halton Region Infectious Disease Report 46

53 Over half of those infected with Coxiella burnetii do not have any symptoms. Acute symptoms of Q fever are variable, and may include high fever, headache, fatigue, cough, diarrhoea, nausea, and sensitivity to light. In less than 5% of cases, chronic Q fever may develop, which often presents as endocarditis (inflammation of the lining of the heart valves). Brucellosis There were no reported cases of brucellosis in Halton in 2017, and three cases in all of Ontario. The last reported case of brucellosis in Halton was in Brucellosis is a disease caused by the Brucella bacteria. Reservoirs of brucellosis include several domestic animals such as cattle, sheep and pigs, as well as wild animals like deer and bison. Humans can become infected with brucellosis through eating or drinking raw dairy products from an infected animal, from breathing in the bacteria, and when the bacteria from the animals enters the body through wounds in the skin or through mucous membranes. Individuals who work with livestock, including farmers and veterinarians, are most at risk for brucellosis. Cattle in Ontario have been declared free of brucellosis. Symptoms of brucellosis most commonly occur within one to two months of exposure to the pathogen, and include fever that comes and goes, headache, weakness, chills, aches and pains, and weight loss. In serious cases, meningitis, endocarditis, and osteomyelitis (bone infection) may occur. Leprosy In 2017, there were no reported cases of leprosy in Halton, and two cases in all of Ontario. The last reported case of leprosy in Halton was in Leprosy is a disease that primarily involves the skin and is caused by the bacterium Mycobacterium leprae. It is likely that the bacterium is transmitted from person-to-person through infected respiratory droplets and nasal secretions. The main symptoms of leprosy include skin lesions and skin growths. The disease can also damage the nervous system and lead to muscle weakness and numbness in the arms, hands, legs, and feet. Symptoms can take many years to appear after becoming infected with the bacteria. Leprosy is not endemic to Canada, and cases reported in Canada are acquired from countries where the disease is endemic. In the southern United States, some armadillos naturally carry the bacteria that cause leprosy, and while it is possible to acquire the disease from an armadillo the risk is very low. Hemorrhagic fevers In 2017, there were no reported cases of hemorrhagic fever in Halton or Ontario. The last case of hemorrhagic fever in Ontario was in Hemorrhagic fevers include a number of different viruses from several families, including Filoviridae (e.g. Ebola and Marburg), bunyaviruses (e.g. Rift Valley fever virus), arenaviruses (e.g. Lujo virus), and flaviviruses (e.g. Dengue virus). Symptoms of viral hemorrhagic fevers may include rapid onset of fever, bleeding under the skin, vomiting blood, blood in stool, bleeding from the nose, and coughing up blood. In severe cases, viral hemorrhagic fever can be 2017 Halton Region Infectious Disease Report 47

54 fatal. While dengue hemorrhagic fever is reportable, the milder, more common illness dengue fever is not reportable. Modes of transmission of viral hemorrhagic fevers vary depending on the virus. Most of the viruses that cause hemorrhagic fevers are transmitted to humans through animal or insect hosts. Ebola and Marburg are transmitted through direct contact with infected bodily fluids (such as blood or semen), while dengue is transmitted through the bite of a mosquito, similar to malaria. Tularemia In 2017, there were no reported cases of tularemia reported in Halton, and one case in all of Ontario. Tularemia is caused by the bacterium Francisella tularensis. The disease is found in several wild and domestic animals, including rabbits, as well as certain insects. Humans can contract the infection in numerous ways including bites from infected ticks, eating infected undercooked meat, handling infected animals, drinking contaminated water, and inhaling dust from contaminated soil. Symptoms of tularemia typically begin within three to five days of exposure to the bacteria, and include fever, chills, muscle pain, and headache. Various other symptoms may also be present, including skin ulcers at the site of infection, swollen lymph nodes, conjunctivitis (pink eye), sore throat or tonsillitis, vomiting or diarrhea, as well as cough, chest pain and difficulty breathing. Similar to Q fever, it has been noted that tularemia has the potential to be used in bioterrorism due to the way that it can spread through aerosolized particles. Yellow fever In 2017, there were no reported cases of yellow fever in Halton or Ontario. Yellow fever is an acute illness that typically occurs within three to six days of becoming infected with the virus from the bite of a mosquito infected with the yellow fever virus. Symptoms include fever, headache, nausea or vomiting, muscle pain, loss of appetite, and jaundice. Serious cases can progress to hemorrhagic symptoms (such as vomiting blood, or bleeding gums and nose) and can be fatal. Yellow fever virus is not endemic to Ontario, and cases reported in Ontario are travel acquired or among those who immigrated to Canada from endemic countries, including areas of Africa and Latin America. Reservoirs of the virus include humans, monkeys, and other vertebrates. Yellow fever is vaccine-preventable, and the vaccine is recommended for those travelling to countries where there is a risk of yellow fever. Rabies The last reported case of human rabies infection in Ontario occurred in Rabies is a viral disease that is transmitted through the bite or scratch of an infected animal. Early symptoms of rabies include fever, headache, and malaise. Later symptoms include anxiety, confusion, excitation, increased salivation, hallucinations, and paralysis. Once symptoms appear, rabies is almost always fatal to both humans and animals. A rabies vaccine 2017 Halton Region Infectious Disease Report 48

55 is available for anyone who has been exposed to animals with rabies or who may be at high risk of contact with rabid animals, which can effectively provide immunity to rabies before or soon after exposure to the virus. Public Health Inspectors investigate all reports of potential human exposures to the rabies virus. In Canada, common sources of rabies are raccoons, skunks, foxes, bats, and coyotes. Ontario has a highly successful rabies eradication program, where flavoured baits containing rabies vaccine are distributed in certain areas of the province to immunize the wild animals that eat them. In 2015, the first reported case of rabies in a raccoon in ten years was reported in Hamilton. Halton had 19 rabies positive animals reported in 2017: one positive bat reported in Oakville, and nine positive raccoons and nine positive skunks reported in Burlington. Raccoon strain rabies had not been seen in Ontario since It is believed to have been re-introduced to Ontario by an infected raccoon that was inadvertently transported, from New York State. Since December 2015, increased rabies prevention and control activities have been initiated to minimize further spread of raccoon strain rabies. Some of these activities include enhanced surveillance, increased rabies vaccine baiting and public education. Psittacosis/ornithosis The last reported case of psittacosis/ornithosis occurred in Ontario in Psittacosis/ornithosis is a disease caused by the bacteria Chlamydophila psittaci. The bacteria are carried by wild and domestic birds, and humans can become infected by inhaling dust from dried faeces or other secretions from infected birds. Person-to-person transmission is rare. Symptoms typically begin within one to four weeks of exposure to the bacteria, and can include fever, headache, light sensitivity, muscle pain and cough. In serious cases, inflammation of the brain, heart muscle, or walls of veins can occur. Anthrax There have been no reported cases of anthrax in humans in Ontario since As anthrax is a rare and severe disease, a single case of non-travel related anthrax in Ontario would be considered an outbreak. Anthrax is caused by the bacterium Bacillus anthracis. The main reservoirs of anthrax are livestock and wild animals, and anthrax spores can be found in soil. The last positive case of anthrax in animals in Ontario was in Anthrax has been known to be used as a bioterrorism agent, and every case should be followed up to determine exposure and whether or not the case was the result of bioterrorism. Anthrax presents clinically in three different ways. Cutaneous anthrax is the most common form of anthrax infection, and occurs when anthrax spores get into the skin through a cut or scrape. Symptoms of cutaneous anthrax include a sore at the site, which may form a black ulcer, as well as fever, malaise, and headache. Inhalation anthrax occurs when anthrax spores are inhaled. Early stages of inhalation anthrax may involve sweats, cough, malaise, nausea, or vomiting. This is followed later by respiratory distress and shock, and has a very high mortality rate. Gastrointestinal anthrax occurs when anthrax spores are ingested. Symptoms include vomiting, abdominal pain, and gastrointestinal bleeding Halton Region Infectious Disease Report 49

56 Lassa fever No cases of Lassa fever have ever been reported in Ontario. Lassa fever is a disease caused by the Lassa virus, and is endemic to areas of Africa including Guinea, Liberia, Nigeria, and Sierra Leone. The virus is transmitted to humans through direct contact with or inhaling particles of faeces from infected wild rodents. It can also be sexuallytransmitted, or spread from person-to-person via exposure to blood and other bodily fluids of infected individuals. Symptoms of Lassa fever appear within six to 21 days of becoming infected with the virus, and can include mild symptoms such as fever, headache, malaise and weakness. Many people do not experience any symptoms. In some people, more serious symptoms occur such as vomiting, pain in the chest and abdomen, bleeding (in the eyes or nose), and organ failure resulting in death. Hantavirus pulmonary syndrome There have been no human cases of hantavirus pulmonary syndrome reported in Ontario since the disease became reportable in Humans can become infected with hantavirus by inhaling or coming in direct contact with the virus in the urine or faeces of infected rodents, or by being bitten by an infected rodent. Hantavirus has been found in deer mice and voles in Ontario. Hantavirus pulmonary syndrome presents as a flu-like illness, which progresses rapidly to more serious symptoms including a drop in blood pressure, fluid-filled lungs, and respiratory failure. The case fatality rate of hantavirus pulmonary syndrome is 35-50%. Plague The last reported human case of the plague in Canada occurred in A single case of the plague in Canada would constitute an outbreak. The plague is caused by the bacteria Yersinia pestis, The plague is endemic in many places throughout the world, including areas of Africa, Europe, North and South America, and Asia. Yersinia pestis is considered a potential bioterrorism agent, and therefore it is important to investigate plague cases to determine whether bioterrorism is a possible source of exposure. The plague can present in three different forms. Bubonic plague is transmitted via the bite of an infected flea or by handling the tissues of an infected animal. Symptoms of bubonic plague include fever and swelling of the lymph nodes. Left untreated, the case fatality of bubonic plague is around 50%. Pneumonic plague is a serious lung infection that occurs when bacteria from an infected person or animal is inhaled. If left untreated, pneumonic plague can result in death. All other forms of plague are referred to as septicaemic plague, which occurs when the Yersinia pestis bacteria spread through the blood stream to other parts of the body, and can be fatal if not treated Halton Region Infectious Disease Report 50

57 Other reportable infectious diseases In addition to the various categories of infectious diseases presented in this report, there were an additional 76 cases of other reportable diseases (meningitis/encephalitis, group A streptococcal disease, tuberculosis, Creutzfeld-Jakob disease) reported to the Halton Region Health Department in 2017, accounting for 3% of all reportable diseases in Halton (Figure 29). There were no cases of acute flaccid paralysis or severe acute respiratory syndrome (SARS) reported in Halton in Figure 29: Other reportable diseases compared to previous five-year average, Halton residents, Source: Integrated Public Health Information System [ ], extracted March 7, *Includes primary viral and unspecified encephalitis; encephalitis/meningitis; bacterial, other, and viral meningitis 2017 Halton Region Infectious Disease Report 51

58 Encephalitis and meningitis In 2017, there were 48 reported cases of encephalitis and/or meningitis reported in Halton, accounting for about 2% of all reportable diseases in Halton. There was one death among a Halton resident who had been diagnosed with meningitis. Encephalitis is an inflammation of the brain. There are many different agents that can cause encephalitis, many of which are viruses. Symptoms of encephalitis include sudden fever, headache, vomiting, sensitivity to light, stiff neck and back, confusion, drowsiness, unsteady gait, and irritability. Loss of consciousness, poor responsiveness, seizures, muscle weakness, sudden severe dementia, memory loss, withdrawal from social interaction, or impaired judgement may also occur. Meningitis is an inflammation of the membranes (called meninges) that surround the brain and spinal cord. Meningitis may be caused by many different viruses and bacteria, or by diseases that can cause inflammation of the tissues of the body without infection. Symptoms of meningitis, which may appear suddenly, often include high fever, severe and persistent headache, stiff neck, nausea and vomiting, as well as changes in behaviour such as confusion, sleepiness, and difficulty waking up. In infants, symptoms of meningitis may include irritability or tiredness, poor feeding, and fever. The age-standardized incidence rates of encephalitis/meningitis combined over the past ten years has varied in Halton due to the small number of cases reported on a year to year basis. In Ontario, the incidence rate has been increasing slightly (Figure 30). In 2017, the agestandardized incidence rate for meningitis/encephalitis was significantly higher in Halton compared to Ontario. Figure 30: Encephalitis and meningitis combined* crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018]. *Includes primary viral and unspecified encephalitis; encephalitis/meningitis; bacterial, other, and viral meningitis 2017 Halton Region Infectious Disease Report 52

59 Invasive group A streptococcal disease In 2017, there were 16 reported cases of invasive group A streptococcal disease (igas) in Halton, accounting for less than 1% of all reportable diseases. There was one death among a Halton resident who had been diagnosed with invasive group A streptococcal disease. igas disease is caused by Streptococcus pyogenes, which is a type of bacteria that commonly infects the skin and mucous membranes, causing strep throat, impetigo, and other relatively mild infections. When these bacteria infect body sites that are normally sterile, such as blood (bacteraemia), cerebrospinal fluid (meningitis), and synovial fluid/joints, the disease is classified as igas disease. Serious cellulitis, necrotizing fasciitis (flesh-eating disease), and streptococcal toxic shock syndrome are forms of igas disease. The disease is generally spread via person-to-person contact including: droplet spread when an infected person coughs or sneezes, direct contact with mucus from the nose or throat of an infected person, or through contact with infected skin sores. igas disease typically occurs more frequently in the late winter and spring in Ontario. The age-standardized rates for igas have been fairly similar in Halton compared to Ontario, and have remained stable over the past ten years, with a slight upwards trend seen in Ontario (Figure 31). In 2017, Halton s age-standardized rate of igas was significantly lower than Ontario. Figure 31: Invasive Group A streptococcal disease crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 53

60 Tuberculosis In 2017, there were 11 reported cases of tuberculosis in Halton, accounting for less than 1% of all reportable diseases in Halton. Tuberculosis is a mycobacterial disease that is a major cause of disability and death, especially among those in developing countries. About 10% of those initially infected will eventually develop active tuberculosis disease, half of those developing the disease during the first two years following infection. 90% of untreated infected individuals will never develop active tuberculosis. Only active cases of tuberculosis are included in this report. Worldwide, industrialized countries have seen downwards trends in mortality and morbidity due to tuberculosis for many years, however, since the mid-1980s, population groups with a high prevalence of HIV infection have experienced increasing rates of tuberculosis. Worldwide, 1-2% of all tuberculosis cases involve a multi-drug resistant strain. In some countries, such as parts of China, India, and Russia, multi-drug resistant tuberculosis is a major public health issue. The ten-year trends in incidence of active tuberculosis have been fluctuating in both Halton and Ontario. Halton has had a general decreasing trend from 2008 to 2017 Figure 32). The fluctuations in rates of tuberculosis are expected as the number of cases in the population is low. The age-standardized rates of infectious tuberculosis in Halton have remained consistently lower than Ontario, and in 2017 this difference was statistically significant. Figure 32: Tuberculosis crude and age-standardized incidence rates (per 100,000), Halton residents compared to Ontario, Sources: Integrated Public Health Information System [ ], extracted March 7, 2018; Population Estimates, IntelliHEALTH, Ontario Ministry of Health and Long-Term Care [2017], extracted November 30, Ontario data: Ontario Ministry of Health and Long-Term Care, Integrated Public Health System database, extracted by Public Health Ontario [March 7, 2018] Halton Region Infectious Disease Report 54

61 Acute flaccid paralysis There were no reported cases of acute flaccid paralysis in Halton in 2017, and four cases in all of Ontario. The last reported case of acute flaccid paralysis in Halton was in Acute flaccid paralysis can be caused by a number of different pathogens, including enteroviruses (including the virus that causes polio), adenoviruses, West Nile Virus, Campylobacter, and botulism. As poliovirus can cause acute flaccid paralysis, it is important to rule out this virus as the causative agent in order to maintain Canada s status as polio-free. A single case of polio in Canada would be considered a public health emergency (see section of this report on Polio). In Canada, acute flaccid paralysis is most often caused by Guillain-Barré Syndrome. Signs and symptoms of acute flaccid paralysis include rapid onset of weakness or paralysis in children less than 15 years old (without other causes like trauma). Acute flaccid paralysis associated with polio is typically asymmetric, often involving one leg or one arm only. Acute flaccid paralysis associated with Guillain-Barré Syndrome can be symmetrical. Creutzfeldt-Jakob disease There was one reported case of Creutzfeldt-Jakob disease (CJD) in Halton in 2017, and 14 cases in all of Ontario. CJD is a rare, degenerative brain disorder. It belongs to a group of diseases called transmissible spongiform encephalopathies, or prion diseases. There are three main forms of classic CJD. The most common is sporadic CJD, the exact cause of which is not known. Familial CJD is associated with a family history of the diseases. Iatrogenic (acquired) CJD occurs when the infection is spread from a person with CJD to another person through surgical or medical treatment, and is very rare. Variant CJD is a fourth, rare form of the disease which has been linked to exposure to cattle with Bovine Spongiform Encephalopathy (often referred to as mad cow ). Signs and symptoms of CJD include confusion, dementia, difficulty walking, loss of control of body movements, and loss of speech. CJD is fatal. Severe Acute Respiratory Syndrome The last reported case of Severe Acute Respiratory Syndrome (SARS) in Canada was in 2003, and the last reported case worldwide was in China in SARS is a viral respiratory illness caused by a coronavirus. The disease was first reported in China in By the summer of 2003, major outbreaks occurred in Canada, the Guangdong Province of China, Hong Kong, Taiwan, Singapore, and Vietnam. There has been no evidence of the virus in humans since SARS is transmitted from person-to-person by close contact, such as when an infected person coughs or sneezes, or through contact with infected bodily fluids. Symptoms of SARS typically begin within two to ten days of exposure to the virus, and may include malaise, fever, cough, shortness of breath, diarrhea, pneumonia, and acute respiratory distress syndrome (life threatening fluid build-up in the lungs) Halton Region Infectious Disease Report 55

62 Part III: Infectious diseases and the social determinants of health While biology plays an important role in how healthy we are, environmental factors (such as where we live, learn, work and play), economic factors (such as our income and level of education) and social factors (such as the availability of social supports and family structure) interact with health. 11 Collectively these factors are known as the social determinants of health. Because social determinants influence health and illness, the burden of infectious disease in Halton is not evenly distributed across the population. In 2017, the low neighbourhood income group had a significantly higher age-standardized incidence rate of reportable infectious diseases when compared to the middle and high neighbourhood income groups. There were no significant differences when comparing the age-standardized incidence rate of reportable infectious diseases in Halton between the middle and high neighbourhood income groups (Figure 33). However, it is important to note that the majority of reported infectious disease cases were from residents of middle and high income neighbourhoods as these populations are much larger in Halton. Higher rates of reportable infectious diseases among Halton residents living in lower-income neighbourhoods may be attributable, at least in part, to the social determinants of health. For example, income-related barriers such as transportation or precarious work conditions (such as working multiple jobs) may decrease the likelihood that individuals will access the care that can prevent, screen for, or treat infectious diseases. Unlike biological factors such as genetics and age, the social determinants of health can be influenced by public policies and other Public Health interventions. 12 Along with protecting health through infection control and immunization against infectious diseases, working to create the environmental, economic and social conditions that best support health is also an important role for public health in reducing the incidence and prevalence of infectious disease. These efforts might include referral to housing supports, mobile community outreach to reduce transportation barriers, low cost/no cost birth control and STI treatment, free needle exchange, and tuberculosis (TB) medication for all clients with active TB Halton Region Infectious Disease Report 56

63 Figure 33: Age-standardized incidence rates (per 100,000), by neighbourhood income group, Halton Region, 2017 Sources: Integrated Public Health Information System [2017], extracted March 7, Postal CodeOM Conversion File (PCCF), Statistics Canada Catalogue no X. Statistics Canada, 2016 Census of Population, Statistics Canada Catalogue no X Note: individuals living in correctional facilities were excluded from analysis. Postal codes L9T 8Z1, L9T 5E6, L9T 273, and L9T 3V9 were excluded from the numerator. The population of people in a correctional or penal institution (in DA ) from the 2011 Census were removed from the denominator. Postal codes from outside of Halton and postal codes that were linked to PO boxes were excluded from analysis Halton Region Infectious Disease Report 57

64 Part IV: Outbreak investigations Halton Region Health Department staff investigate outbreaks under the mandate to decrease or eliminate the risks to health presented by infectious diseases as outlined in the Health Protection and Promotion Act. Although many infectious disease investigations involve single sporadic cases (i.e. they can t be linked to other cases), contaminated food or water, or personto-person contact can result in clusters of illness affecting large numbers of people. Some outbreaks have required significant Halton Region Health Department resources, especially those of longer duration. All institutional enteric and respiratory outbreaks are reportable to the Halton Region Health Department. Outbreaks of enteric illness in institutions are most frequently caused by viruses such as norovirus, however, bacteria and other pathogens may cause outbreaks as well. Outbreaks of respiratory infections in institutions are typically caused by a variety of respiratory viruses such as influenza A and B, rhinovirus, coronavirus, respiratory syncytial virus (RSV), and other viruses. Examples of bacteria that cause respiratory outbreaks in institutions include Chlamydia pneumonia, Legionella, and Mycoplasm pneumoniae (atypical pneumonia). Since each outbreak requires its own case definition, health unit staff members collaborate with the facility to develop a case definition based on the outbreak s characteristics and any agent identified through laboratory testing. Health Department staff provide recommendations for the prevention, detection, and management of infectious disease outbreaks. Public health units in Ontario are required to report both confirmed and suspect respiratory and enteric outbreaks through the Integrated Public Health Information System (iphis). The Provincial Case Definitions 3 section of the 2017 Infectious Diseases Protocol provides definitions for confirmed and suspect enteric and respiratory outbreaks. There were a total of 129 outbreaks investigated by the Halton Region Health Department in Halton Region Infectious Disease Report 58

65 Respiratory outbreaks In 2017, there were a total of 85 respiratory outbreaks investigated by the Halton Region Health Department, accounting for 66% of all (both respiratory and enteric) outbreaks reported. Agent In 2017, the most common agents involved in respiratory outbreaks the Health Department investigated were influenza A (35%), unspecified respiratory agents (20%), and rhinovirus (8%) (Figure 34). Figure 34: Respiratory outbreaks investigated in Halton by agent, 2017 compared to average. Source: Integrated Public Health Information System [2017], extracted March 8, Integrated Public Health Information System [ ], extracted March 27, 2017 *Other category includes: adenovirus, entero/rhinovirus, enterovirus, food poisoning unknown/unspecified, and respiratory infection other (specify) Halton Region Infectious Disease Report 59

66 Location In 2017, the majority of respiratory outbreaks investigated by the Health Department involved long-term care homes (72%), followed by retirement homes (18%), unregulated or special homes (4%), child care centres (2%), community settings (2%),and hospitals (2%) ( Figure 35). Figure 35: Respiratory outbreaks investigated in Halton, by location, 2017 compared to average. Source: Integrated Public Health Information System [2017], extracted March 8, Integrated Public Health Information System [ ], extracted March 27, 2017 Seasonal variation In 2017, the majority of outbreaks investigated in Halton were in the winter months, particularly December, January and February (Figure 36). Figure 36: Respiratory outbreaks investigated in Halton, by month of onset, Source: Integrated Public Health Information System [2017], extracted March 8, Halton Region Infectious Disease Report 60

67 Outbreak duration The duration of outbreaks varied from approximately one week to up to five weeks or longer. The most common outbreak duration was 2 to <3 weeks (41%) (Figure 37). Figure 37: Respiratory outbreaks investigated in Halton, by duration, 2017 compared to average. Source: Integrated Public Health Information System [2017], extracted March 8, Integrated Public Health Information System [ ], extracted March 27, 2017 Number of cases investigated Of the total 1,146 people who became ill with a respiratory illness, 753 (66%) were clients and 393 (34%) were staff of the affected premises. In total, 10,394 clients and 16,035 staff were at risk of becoming ill because of an outbreak in their facilities, and subject to increased control procedures (Table 2). Table 2: Total number of clients and staff who were at risk and who were ill, by location of the outbreak, respiratory outbreaks, Halton Region, Location of outbreak Clients Staff Ill At Risk % Ill At Risk % Long-term care home Hospital Retirement residence Unregulated/special homes Community setting Total % Source: Integrated Public Health Information System [2017], extracted March 14, Halton Region Infectious Disease Report 61

68 Enteric outbreaks In 2017, there were a total of 44 enteric outbreaks investigated by the Halton Region Health Department, accounting for 34% of all outbreaks (respiratory and enteric) reported. Agent In 2017, the agent was unknown for more than half (61%) of enteric outbreaks. For outbreaks where the agent was known, norovirus was the most common agent (32%) (Figure 38). Figure 38: Enteric outbreaks investigated in Halton, by agent, 2017 compared to average. Source: Integrated Public Health Information System [2017], extracted March 8, Integrated Public Health Information System [ ], extracted March 27, 2017 *Other category includes: calicivirus/norovirus, enterovirus/echovirus, food poisoning, gastroenteritis other (specified), giardia lamblia/intestinalis/duodenalis, hepatitis A virus, salmonella montevideo, and blanks Halton Region Infectious Disease Report 62

69 Location In 2017, the majority of enteric outbreaks investigated by the Health Department took place at child care centres (45%), followed by long-term care homes (30%), retirement residences (20%), and within the community (5%) (Figure 39). Figure 39: Enteric outbreaks investigated in Halton, by location, 2017 compared to average. Source: Integrated Public Health Information System [2017], extracted March 8, Integrated Public Health Information System [ ], extracted March 27, 2017 Seasonal variation In 2017, the majority of outbreaks investigated in Halton were in the winter and early spring. (Figure 40). Figure 40: Enteric outbreaks investigated in Halton, by month of onset, Source: Integrated Public Health Information System [2017], extracted March 8, Halton Region Infectious Disease Report 63

70 Outbreak duration The duration of outbreaks varied from less than one week to up to five weeks or longer. The most common outbreak duration was 1 to <2 weeks (Figure 41). Figure 41: Enteric outbreaks investigated in Halton, by duration, 2017 compared to average. Source: Integrated Public Health Information System [2017], extracted March 8, Integrated Public Health Information System [ ], extracted March 27, 2017 Number of cases investigated Of the total 678 people who became ill, 476 (70%) were clients and 202 (30%) were staff of the affected premises. In total, 3,569 clients and 3,312 staff were at risk of becoming ill because of an outbreak in their facilities, and subject to increased control procedures (Table 3). Table 3: Total number of clients and staff who were at risk and who were ill, by location of the outbreak, enteric outbreaks, Halton Region, 2017 Location of outbreak Clients Staff Ill At Risk % Ill At Risk % Long-term care home Retirement residence Child care centre Community setting N/A N/A N/A Total Source: Integrated Public Health Information System [2017], extracted March 14, Halton Region Infectious Disease Report 64