2009 Halton Region Health Department

Transcription

1 2009 Halton Region Health Department Infectious DISEASE REPORT Photo credit: James Gathany, CDC/Judy Schmidt

2 Copyright Restrictions: None - This image is in the public domain and thus free of any copyright restrictions. As a matter of courtesy we request that the content provider be credited and notified in any public or private usage of this image. Content Providers(s): Photo Credit: CDC/ Judy Schmidt James Gathany

3 2009 Halton Region Infectious Disease Report September Halton Region Infectious Disease Report 1

4 2009 Halton Region Infectious Disease Report Table of Contents PART I: LEADING REPORTABLE INFECTIOUS DISEASES IN 2009 IN HALTON...7 COMPARISON WITH ONTARIO AGE-STANDARDIZED INCIDENCE RATES FOR PART II: CATEGORIES OF INFECTIOUS DISEASES...13 VACCINE-PREVENTABLE DISEASES...13 Influenza...14 Streptococcus pneumoniae...15 Pertussis...16 FOOD- AND WATER-BORNE DISEASES...17 Campylobacter enteritis...18 Salmonellosis...19 SEXUALLY-TRANSMITTED INFECTIONS...20 Chlamydia...21 Gonorrhoea...29 Syphilis...30 SELECTED BLOOD-BORNE INFECTIONS...33 Hepatitis C...34 Hepatitis B...35 SELECTED DISEASES TRANSMITTED BY DIRECT PERSONAL CONTACT OR RESPIRATORY ROUTES...36 Tuberculosis...37 Group A Streptococcal Infections...38 DISEASES TRANSMITTED BY INSECTS AND ANIMALS...39 OTHER REPORTABLE INFECTIOUS DISEASES...39 Encephalitis/Meningitis...39 Group B Streptococcal Infections...40 PART III: OUTBREAK INVESTIGATIONS...42 OUTBREAKS BY LOCATION...42 RESPIRATORY OUTBREAKS...43 ENTERIC OUTBREAKS...44 OUTBREAK TRENDS...45 NUMBER OF CASES INVESTIGATED...47 PART IV: THE H1N1 PANDEMIC IN HALTON...48 BACKGROUND...48 APPENDIX A: HEALTH PROTECTION AND PROMOTION ACT...59 APPENDIX B-1: THE NUMBER OF REPORTED CASES OF COMMUNICABLE DISEASE IN 2009 COMPARED TO 2008 AND THE PREVIOUS 5-YEAR AVERAGE ( ), AND THE AGE AND SEX STANDARDIZED RATES PER 100,000 POPULATION, HALTON REGION...62 APPENDIX B-2: REPORTABLE DISEASES FOR WHICH THERE WERE NO REPORTED CASES OF INFECTION IN THE PAST FIVE YEARS APPENDIX C: CASE CLASSIFICATIONS, H1N1 INFLUENZA PANDEMIC, WAVE APPENDIX D: CASE CLASSIFICATIONS, H1N1 INFLUENZA PANDEMIC, WAVE Halton Region Infectious Disease Report 2

5 List of Figures Figure 1: The 10 most frequently reported infectious diseases, Halton Region 2009 compared to previous five-year annual average... 9 Figure 2: The 10 most frequently reported infectious diseases, number of cases by year, Halton Region Figure 3: The 10 most frequently reported infectious diseases, age-standardized incidence rates per 100,000 population, Halton Region Figure 4: Most frequently reported vaccine-preventable diseases, Halton Region, 2009 compared to previous 5-year annual average Figure 5: Influenza, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario, Figure 6: Invasive Streptococcus pneumoniae, age standardized incidence rates per 100,000 population, Halton Region Figure 7: Pertussis, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario, Figure 8: Most frequently reported food- and water-borne diseases, Halton Region, 2009 compared to previous 5-year annual average Figure 9: Campylobacter enteritis, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario, Figure 10: Salmonellosis, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario, Figure 11: Sexually-transmitted infections, Halton Region, 2009 compared to previous five-year annual average Figure 12: Chlamydia, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario, Figure 13: Chlamydia, age-standardized rates, by sex, Halton Region, Figure 14: Chlamydia, number of reported cases, by age group, Halton Region, Figure 15: Chlamydia, number of reported cases, by age group, females, Halton Region, Figure 16: Chlamydia, age-specific incidence rates, by age group, females, Halton Region, Figure 17: Chlamydia, number of confirmed cases, by age group, males, Halton Region, Figure 18: Chlamydia, age-specific rates of incidence, by age group, males, Halton Region, Figure 19: Proportion of total reported cases of chlamydia, by municipality, Halton Region, Figure 20: Gonorrhea, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario Figure 21: Number of cases of syphilis, Halton Region, 2009 compared to previous fiveyear annual average Figure 22: Infectious and non-infectious syphilis, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario, Halton Region Infectious Disease Report 3

6 Figure 23: The number of selected blood-borne infections, Halton Region, 2009 compared to previous 5-year annual average Figure 24: Hepatitis C, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario, Figure 25: Hepatitis B, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario, (2009 Ontario data not available at the time of this report) Figure 26: Number of cases of selected diseases spread by close contact or respiratory routes, Halton Region 2009 compared to previous five-year annual average Figure 27: Tuberculosis, crude incidence rate per 100,000 population, Halton Region, Figure 28: Severe group A streptococcal infections, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario, Figure 29: Encephalitis/Meningitis, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario, Figure 30: Group B Streptoccocal Infections, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario, Figure 31: Type of outbreak by municipality, Halton Region, Figure 32: Outbreaks by type of location, Halton Region, Figure 33: Respiratory outbreaks by causative agent, Halton Region, Figure 34: Enteric outbreaks by causative agent, Halton Region, Figure 35: Type of outbreak by month of onset, Halton Region, Figure 36: Type of outbreak by outbreak duration, Halton Region, Figure 37: ph1n1 case reports, by date of onset, Halton Region, April 20 - September 15, 2009 (wave 1) Figure 38: Number of schools reporting absenteeism rate of 2% or more due to influenza-like illness, Halton Region Schools (Public & Catholic School Board & Private Schools), May 7-June 19, 2009 (wave 1) Figure 39: Number of FRI and SRI cases reported by Halton Region hospitals, mid- April to mid-september, 2009 (wave 1) Figure 40: ph1n1 influenza surveillance, number of cases by case classification and age group, Halton Region, wave Figure 41: ph1n1 influenza surveillance, number of cases by case classification and age group, Halton Region, wave Figure 42: ph1n1 case reports, by date of onset, Halton Region, September-December, 2009 (wave 2) Figure 43: Dates of onset for cases reported in waves 1 and 2 of the ph1n1 Influenza pandemic, Halton Region, April 2009 January Figure 44: Total number of laboratory tests and the proportion of laboratory tests positive for ph1n1, by week, Halton Region, Influenza Season 2009/10 (wave 2) Figure 45: School absenteeism surveillance, proportion of schools reporting absenteeism due to Influenza-like illness of 2% or more, by week, Halton Region, Influenza Season 2009/10 (wave 2) Halton Region Infectious Disease Report 4

7 Figure 46: Proportion of emergency department visits due to influenza-like illness, Halton Region hospitals, by hospital site, September to December, 2009 (wave 2) Table 1: Table 2: List of Tables Number, incidence rates and age-standardized* incidence rates of the top ten most frequently reported infectious diseases in Halton in 2009, compared to the previous two years Age-standardized incidence rates per 100,000 population for the top ten most frequently reported infectious diseases, Halton Region 2009 compared to Ontario.. 12 Table 3: Number of reported chlamydia infections, by sex, Halton Region, Table 4: Number of outbreaks, by type of outbreak and location, Halton Region, Table 5: Number of outbreaks by location, Halton Region, Table 6: Number of staff and clients who were ill or at risk, by location of the outbreak, Halton Region, Halton Region Infectious Disease Report 5

8 2009 Halton Region Infectious Disease Report The 2009 Halton Region Infectious Disease Report summarizes the incidence of infectious (communicable) 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 by toxins from these organisms. Infectious diseases are spread from one host to another by 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 Public Health under the 1990 Health Protection and Promotion Act (HPPA) is in Appendix A. The 2009 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 program components. Staff members investigate reports of individual cases and respond to outbreaks in both the community and in institutions such as long-term care homes, child care settings, schools, colleges, and prisons. In addition to investigating disease reports and preventing further spread of disease, the Department also conducts inspections to prevent disease, including inspections of licensed child care settings, personal services settings, food premises, small drinking water systems, and swimming pools. The Health Department is also mandated to prevent and reduce the burden of infections through education, certification programs, and the provision of various clinical services such as immunization clinics, sexual health clinics, and travel health clinic services. Presentation of the Results Part I of this report provides an analysis of the 10 most frequently reported infectious diseases in Halton Region, along with comparisons to the last two years of data (2007 and 2008), the previous five-year annual average, the ten-year trend as well as comparisons to Ontario overall. Part II of the report summarizes all cases of reportable infectious disease, grouping these into categories based on major immunization strategies (e.g., vaccine-preventable diseases) and main modes of transmission, with a focus on chlamydia. Part III of the report presents an analysis of all the outbreaks that were investigated by the Halton Region Health Department during the course of the year Finally, Part IV summarizes the epidemiology and surveillance activities of the 2008/09 and 2009/2010 influenza seasons, the Halton Region Influenza H1N1 pandemic Halton Region Infectious Disease Report 6

9 Part I: Leading Reportable Infectious Diseases in 2009 in Halton In 2009, 1,836 cases of reportable infectious diseases were reported to the Halton Region Health Department for investigation (Table 1). Table 1 shows the 10 most frequently reported infectious diseases that accounted for 86% of the total cases. Figure 1 shows the number of cases of these diseases in 2009 compared to the previous five-year annual average. In 2008 and 2007 there were 1,439 and 1,323 cases of infectious diseases, respectively showed a 28% increase from Most of the increase in 2009 was attributable to the increase in the number of cases of both chlamydia and influenza. It needs to be noted that this report is based on reports of infectious diseases for the calendar year Influenza, however, is always reported for the season which begins in September of the previous year (2008) and ends in August of the current calendar year on which this report is based (2009). Given that the H1N1 pandemic was a significant event in 2009, with two waves spanning two influenza seasons (2008/09 and 2009/10), H1N1 influenza cases from wave 1 only are included in the 2008/09 influenza season (sections I and II). Information on both wave 1 and 2 of the H1N1 pandemic in Halton Region is provided in section IV of this report Halton Region Infectious Disease Report 7

10 Table 1: Number, incidence rates and age-standardized* incidence rates of the top ten most frequently reported infectious diseases in Halton in 2009, compared to the previous two years Disease Total Reported Confirmed Cases Incidence Rate per 100,000 Standardized Incidence Rate per 100,000 Total Reported Confirmed Cases Incidence Rate per 100,000 Standardized Incidence Rate per 100,000 Total Reported Confirmed Cases Incidence Rate per 100,000 Standardized Incidence Rate per 100,000 Chlamydia Influenza** Campylobacteriosis Hepatitis C Salmonellosis Gonorrhea Giardiasis Streptococcus Pneumoniae - invasive Amebiasis Cryptosporidiosis 10 Total Number of Reported Confirmed Cases Top 10 in each year All Other Reported Cases 1,585 1,218 1, TOTAL NUMBER OF REPORTED CASES 1,836 1,439 1,323 * Rates were age standardized to the 1991 Canadian Population. ** Influenza numbers are provided for the Influenza Season of Sept 1 st to Dec 31 st of previous year and Jan 1 st to August 31 st of the current year. This number includes H1N1 cases for wave 1. [Source: Integrated Public Health Information System (iphis, )] 2009 Halton Region Infectious Disease Report 8

11 Figure 1 shows the same 10 most frequently reported infectious diseases as a horizontal bar graph. The numbers of cases for 2009 are compared to the average number of cases per year in the previous five years 2004 to 2008 (the numbers for influenza pertain to the influenza seasons, not annual counts). Chlamydia Influenza - total Campylobacteriosis Hepatitis C Disease Salmonellosis Gonorrhea Annual Average Giardiasis Streptococcus Pneumoniae - invasive Amebiasis Cryptosporidiosis Number of Reported Cases Figure 1: The 10 most frequently reported infectious diseases, Halton Region 2009 compared to previous five-year annual average. [Source: Reportable Disease Information System ( ) and Integrated Public Health Information System ( )] Of the ten most frequently reported infectious diseases in Halton Region in 2009, chlamydia and gonorrhea are sexually transmitted infections; influenza and Streptoccocus pneumoniae respiratory infections; campylobacter enteritis, salmonellosis, giardiasis, amebiasis and cryptosporidiosis are food and water-borne diseases; and hepatitis C is a blood-borne infection. Two of these diseases-influenza and Streptococcus pneumoniae are vaccine preventable diseases. The full list of reportable infectious diseases for Ontario for 2009 is provided in Appendix A. Figure 2 shows the trend in the total number of new cases each year for the 10 most frequently reported infectious disease over the past ten years Halton Region Infectious Disease Report 9

12 Number of Cases Disease Influenza - total Hepatitis C Gonorrhea Streptococcus Pneumoniae - invasive Cryptosporidiosis Chlamydia Campylobacter enteritis Salmonellosis Giardiasis Amebiasis Figure 2: The 10 most frequently reported infectious diseases, number of cases by year, Halton Region [Source: Reportable Disease Information System ( ) and Integrated Public Health Information System ( )] Figure 3 is similar to Figure 2 but shows age-standardized incidence rates rather than number of cases Halton Region Infectious Disease Report 10

13 Std. Incidence Rate/100, Chlamydia Campylobacter enteritis Salmonellosis Giardiasis Amebiasis Influenza - total Hepatitis C Gonorrhea Streptococcus Pneumoniae - invasive Cryptosporidiosis Figure 3: The 10 most frequently reported infectious diseases, age-standardized incidence rates per 100,000 population, Halton Region [Source: Reportable Disease Information System ( ) and Integrated Public Health Information System ( )]. Appendix B-1 presents a complete list of the reported cases of infectious disease in 2009 and the corresponding age-standardized incidence rates for the current and previous year (2008). Significant changes in rates from 2008 are indicated by arrows. Appendix B-2 presents a list of those reportable infectious diseases for which there were no reported cases in 2009 or in the previous five years, Halton Region Infectious Disease Report 11

14 Comparison with Ontario Age-standardized Incidence Rates for 2009 In 2009, there were some differences between the age-standardized incidence rates of the 10 most frequently reported infectious diseases in Halton as compared to Ontario (Table 2). The standardized incidence rates of chlamydia, hepatitis C, gonorrhea and amebiasis were statistically significantly lower for Halton than Ontario. Table 2: Age-standardized incidence rates per 100,000 population for the top ten most frequently reported infectious diseases, Halton Region 2009 compared to Ontario. Disease HALTON 2009 Agestandardized incidence rate per 100,000 (95% CI) ONTARIO 2009 Agestandardized incidence rate per 100,000 (95% CI) Age-standardized Incidence Ratio Percentage (95% CI) Chlamydia ( ) ( ) 0.67 ( ) Influenza ( ) N/A 2 N/A 2 Campylobacter enteritis 23.6 ( ) 24.4 ( ) 1.01 ( ) Hepatitis C Salmonellosis Gonorrhea Giardiasis Streptococcus pneumoniae - invasive Amebiasis 21.8 ( ) N/A 2 N/A ( ) 18.2 ( ) 1.09 ( ) 14.6 ( ) 30.2 ( ) 0.50 ( ) 10.5 ( ) 11.4 ( ) 0.93 ( ) 7.8 ( ) 8.3 ( ) 0.94 ( ) 3.2 ( ) 5.6 ( ) 0.66 ( ) Cryptosporidiosis 2.0 ( ) 2.7 ( ) 1.5 ( ) Notes: (1) Influenza data are not available for the 2008/09 Influenza Season (calculated as of Sept 1 st to Dec 31 st of previous year and Jan 1 st to August 31 st of the year of reporting). (2) Ontario data were not available at the time of writing of this report. [Source: Integrated Public Health Information System (2010) and Ministry of Health and Long-Term Care (2010)] 2009 Halton Region Infectious Disease Report 12

15 Part II: Categories of Infectious Diseases The data in this section of the report is discussed under the following categories: 1. Vaccine Preventable Diseases 2. Food- and Water-borne Diseases 3. Sexually-transmitted Infections 4. Blood-borne Infections 5. Diseases Transmitted by Direct Personal Contract and Respiratory Routes 6. Diseases Transmitted by Insects and Animals The number of reported cases for Halton Region is presented, along with comparisons to the previous five-year annual average. Age standardized incidence rates are also included allowing for comparison to the province and other health regions. Vaccine-Preventable Diseases Immunization has played a key role in reducing the burden of many diseases and has even eradicated (world-wide) or eliminated (e.g., continent-wide) some diseases that in the past century have caused major illness and loss of life. Illness from nine infectious diseases (i.e., smallpox, diphtheria, pertussis, tetanus, paralytic polio, measles, mumps, rubella, and H. influenzae type b) has decreased by 94% to 100% since the beginning of the 20th century (CDC, 2006). The publicly-funded chickenpox vaccine was released in January 2005 and added to the children s immunization schedule. As of January 2005, the first year for which case-specific data is available, individual laboratory-confirmed reports or those cases resulting in complications or hospitalization were reportable to the Health Department. Therefore, many cases convalescing at home were not reported to the Halton Region Health Department. Canadian children under the age of six, now receive immunization against 11 diseases. In 2009 approximately 5,450 babies were born in Halton each needing up to 12 injections before the age of two. Some vaccines require only a single dose, some require multiple doses over a period of years; some are available combined, others must be given separately. Because vaccines have different levels of effectiveness and/or do not cover all strains/sub-types of the organisms at which they are aimed, not all vaccines are equally effective. Also, coverage of the population is not 100%. This is why it is important to monitor the incidence of vaccine-preventable diseases. In 2009, 460 Halton residents of all ages were diagnosed with vaccine-preventable diseases, accounting for 25% of the total cases of reportable infectious diseases that year Halton Region Infectious Disease Report 13

16 Figure 4 shows the number of new cases of vaccine-preventable diseases in Halton Region in 2009 compared to the previous five-year annual averages Number of Reported Cases Influenza - Total Annual Average Pertussis Chickenpox Mumps Streptococcus Pneumoniae - invasive Disease Figure 4: Most frequently reported vaccine-preventable diseases, Halton Region, 2009 compared to previous 5-year annual average. [Source: Reportable Disease Information System ( ) and Integrated Public Health Information System ( ).] Note that 4-year comparison data is provided for chickenpox which became reportable in Influenza Of the 460 new cases of potentially vaccine-preventable disease, 402 were residents of Halton diagnosed with influenza (during the September 1, 2008, to August 31, 2009, influenza season). Influenza is a highly infectious respiratory illness caused by one of the three types of influenza virus: A, B and C (C is not common nor an important cause of illness and does not have a vaccine). In contrast to the common cold, symptoms of influenza are more sudden in onset and more severe (fever, headache and muscle ache, profound tiredness), especially in the very young, old, and immunocompromised. Many cases of influenza are not diagnosed or reported to the Halton Region Health Department because infected individuals often do not seek medical attention and physicians, when visited, often do not seek laboratory confirmation. Influenza derives its importance due to the rapidity with which epidemics evolve, the widespread morbidity, and the seriousness of complications, notably viral and bacterial pneumonia (Heymann, 2004). Looking at the previous three seasons, the number of influenza cases decreased from 250 in the 2004/05 season to 148 and 118 in 2005/06 and 2006/07 seasons, respectively. The numbers increased to 184 cases in the 2007/08 season and again to 402 in the 2008/09 season Halton Region Infectious Disease Report 14

17 The 2008/2009 season saw a novel strain of influenza sub-typed as H1N1, the pandemic strain. Of the 402 confirmed cases of influenza during the 2008/09 season, 295 (73%) were sub-typed with the pandemic strain H1N1. For details on both waves of the H1N1 pandemic in Halton, please refer to section IV of this report. Between 1997 and 2003, Halton age standardized incidence rates were similar or below those of the province (Fig. 5). The 2004 age standardized incidence rate was higher for Halton than Ontario. The impact of influenza is highly variable however, and therefore annual fluctuations above or below the provincial average are not surprising. The number of laboratory confirmed cases of influenza are a useful indication of the trend in influenza, particularly during the influenza season for tracking the timing and severity of the season. However the actual numbers are always an underestimate because many cases are not sent for laboratory testing. 90 Std. Incidence Rate/100, Halton Year Ontario Figure 5: Influenza, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario, Note: Influenza age standardized incidence rate for Halton in 2006 may not be reliable since age was missing for 5% of cases. Seasonal influenza data was not available for Ontario for at the time of writing of this report. [Source: Reportable Disease Information System ( ), Integrated Public Health Information System ( ), Ministry of Health and Long-Term Care (2010).] Streptococcus pneumoniae In 2009, there were 42 reported cases of invasive Streptococcus pneumoniae, accounting for 9% of the reportable vaccine-preventable diseases. Pneumococcal disease is a major cause of pneumonia (not reportable) and meningitis (reportable) among children and the elderly. Streptococcus pneumoniae became reportable in the year 2001, therefore this first year of data may not be reliable. As seen in Figure 6, the age standardized incidence rates in Halton were 2009 Halton Region Infectious Disease Report 15

18 quite variable in the past five years of reporting, as would be expected because of the relatively small numbers. In 2009, the Halton age standardized incidence rate for this infectious disease (7.8 per 100,000 population) was similar to the provincial rate (8.3 per 100,000 population) (Table 2) Std. Incidence Rate/100, Halton Ontario Figure 6: Invasive Streptococcus pneumoniae, age standardized incidence rates per 100,000 population, Halton Region Note: Data for Ontario for the years were not available at the time of writing of this report. [Source: Reportable Disease Information System ( ), Integrated Public Health Information System ( ), Ministry of Health and Long-Term Care (2010).] Pertussis Pertussis accounted for 2% of the reportable vaccine-preventable cases of infection. In 2009 there were 9 new reported cases of pertussis compared to the previous five-year annual average of 19 cases and the 24 cases reported in Pertussis, or whooping cough, is an acute bacterial infection of the respiratory tract caused by Bordetella pertussis (Heymann, 2004). In most industrialized countries, infants under the age of six months are at greatest risk as they are often too young to have completed primary immunization. In non-immunized populations, especially those with underlying malnutrition and multiple enteric and respiratory infections, pertussis is among the most lethal diseases of infants and young children. The average incubation period is between 9 and 10 days, but may range from 6 to 20 days. This infectious disease is spread by direct contact with discharges from respiratory mucous membranes of infected persons by the airborne route, probably via droplets. Older siblings, and sometimes parents, are frequently carriers of the bacteria which can infect younger children who are not yet immunized. Susceptibility of non-immunized individuals is universal and secondary attack rates of up to 90% in non-immune household contacts have been documented. Incidence is highest in children under five years of age, except where infant vaccination programs have been very effective, and a shift has occurred toward adolescent 2009 Halton Region Infectious Disease Report 16

19 population. Milder and missed atypical cases of infection may occur in all age groups. Cases in previously immunized adolescents and adults in countries with long-standing and successful immunization program may occur because of waning immunity. These cases are a source of infection for non-immunized or under-immunized children Std. Incidence Rate/100, Halton Year Ontario Figure 7: Pertussis, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario, [Source: Reportable Disease Information System ( ), Integrated Public Health Information System ( ), Ministry of Health and Long-Term Care (2010).] The age standardized incidence rates of pertussis in Halton have generally been lower than the age standardized incidence rates of the province, but have followed a similar overall pattern (Fig. 7). Food- and Water-borne Diseases Infectious diseases spread by food and water are caused by bacteria, parasites and viruses that have found their way into the water supply or food source from an infected animal or person. Because the route of exposure to food- and water-borne diseases is by ingestion and because the symptoms are usually primarily related to the digestive tract (through by no means always), these diseases are often also referred to as enteric diseases, meaning relating to the intestine. Many of these diseases are also transmitted from person to person sometimes, even though there is reasonably careful attention paid to personal hygiene. These diseases may cause nausea, vomiting, abdominal pain, diarrhoea, bloody stools, fever, and systemic illness that can be severe. Illness caused by toxins (e.g., Staphylococcus aureus) or other toxic agents can also be spread by food and water. Bacteria can also form toxins in food that can cause illness. In 2009, 325 Halton residents were diagnosed with a food- or water-borne disease, accounting for 18% of the total cases of reportable infectious diseases that year Halton Region Infectious Disease Report 17

20 Figure 8 shows the number of new cases of food- and water-borne diseases in Halton Region in 2009 compared to the previous five-year annual average. 180 Number of Reported Cases Annual Average Campylobacteriosis Salmonellosis Giardiasis Disease Amebiasis Cryptosporidiosis Yersiniosis Figure 8: Most frequently reported food- and water-borne diseases, Halton Region, 2009 compared to previous 5-year annual average. [Source: Reportable Disease Information System ( ) and Integrated Public Health Information System ( ).] In addition to the diseases highlighted in Figure 8, there were also a total of 28 cases of the following diseases, accounting for the remaining 9% of this disease category: cyclosporiasis, hepatitis A, legionellosis, listeriosis, shigellosis, typhoid fever, and verotoxin-producing Escherichia coli. For these, the numbers have remained fairly stable when compared to the previous five-year average. Please refer to Appendix B-1 for the number of reported cases in 2009 for these remaining diseases. Campylobacter enteritis Of the 325 cases of reported food- and water-borne infectious disease in Halton, 119 (37%) were diagnosed with campylobacter enteritis. There were 137 cases of campylobacter enteritis reported on average per year in the previous five years (Fig. 8). Animals, most frequently poultry and cattle, are the reservoirs of the causative organisms. The most common mode of transmission of this disease is through ingestion of the organisms in undercooked meat, contaminated food or water, or raw milk (Heymann, 2004). Over the past 10 years, the age standardized incidence rates in Halton followed the gradually declining incidence rates experienced in Ontario (Fig. 9). In 2006, however, Halton s incidence 2009 Halton Region Infectious Disease Report 18

21 rate increased again to 38.3 cases per 100,000 population. The increased incidence of campylobacter enteritis in 2006 may be attributed to international travel, national and international food distribution (i.e., contaminated food source), or increase in diagnosis and reporting by physicians, or may be just chance variation. In 2009, the Halton age standardized incidence rate of campylobacter enteritis reached a 10-year low of 23.6 cases per 100,000 population. This rate was similar to the Ontario rate in 2009 (Table 2) Std. Incidence Rate/100, HaltonYear Ontario Figure 9: Campylobacter enteritis, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario, [Source: Reportable Disease Information System ( ), Integrated Public Health Information System ( ), Ministry of Health and Long-Term Care (2010).] Salmonellosis Salmonellosis accounted for another 29% of the food- and water-borne infections (93 cases). There were 98 cases of salmonellosis reported on average per year in the previous five years (Fig. 8). Salmonellosis is classified as a food-borne disease because contaminated food, mainly of animal origin, is the predominant mode of transmission Halton Region Infectious Disease Report 19

22 35.0 Std. Incidence Rate/100, Halton Year Ontario Figure 10: Salmonellosis, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario, [Source: Reportable Disease Information System ( ), Integrated Public Health Information System ( ), Ministry of Health and Long-Term Care (2010).] Over the past 10 years, the age standardized incidence rates of salmonellosis in Halton fluctuated along with the Ontario rates (Fig. 10). The high rate in Halton in 2005 is attributed to a single outbreak in a food premise. In 2009, the age standardized incidence rate in Halton, 19.8 cases per 100,000 population, was similar to the provincial rate (Table 2). Sexually-transmitted Infections In 2009, 793 Halton residents were diagnosed with a sexually-transmitted infection, accounting for 43% of the total cases of reportable infectious diseases that year. Figure 11 shows the number of new cases of sexually-transmitted infection in Halton Region in 2009 compared to the previous five-year annual average Halton Region Infectious Disease Report 20

23 Number of Reported Cases Chlamydia Gonorrhea HIV AIDS Syphilis - Infectious Disease Annual Average. Figure 11: Sexually-transmitted infections, Halton Region, 2009 compared to previous five-year annual average. [Source: Reportable Disease Information System ( ) and Integrated Public Health Information System ( ).] Chlamydia Of the 793 cases of reported sexually-transmitted infections, 684 were diagnosed with chlamydia. This accounted for 87% of all the sexually-transmitted infections for Halton residents. There were 434 reported cases on average per year in the previous five years (Fig. 11). Chlamydia is the most common bacterial sexually-transmitted infection. It manifests in men primarily as urethritis, and in females as cervical infection (Heymann, 2004). However, the majority of infections are asymptomatic. Up to 70% of sexually active females with chlamydia infections are asymptomatic (Heymann, 2004). Complications of chlamydial infection include infertility and congenital infection. Asymptomatic infections can also be found in 1% to 25% of sexually active men. Therefore, this disease is likely to be underreported Halton Region Infectious Disease Report 21

24 300.0 Std. Incidence Rate/100, Halton Ontario Figure 12: Chlamydia, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario, [Source: Reportable Disease Information System ( ), Integrated Public Health Information System ( ), Ministry of Health and Long-Term Care (2010).] The age standardized incidence rates of chlamydial infections in Halton showed a rising trend between 2000 and 2009 (Fig. 12). These rates followed the general upward trend experienced in Ontario overall, with Halton s age standardized incidence rates remaining significantly below the provincial rates. The increasing incidence of chlamydia has also been noted for Canada as well as Ontario. In Halton the rates increased 161% between 2000 and 2009, from 65.4 per 100,000 to per 100,000 residents. Some of this increase is attributed to improved quality and acceptability of screening and testing methods. However, chlamydia is a hidden epidemic due to lack of awareness of the problem and because the majority of cases are asymptomatic but still infectious. Awareness raising initiatives continue to be critical components of promotional strategies targeting the importance of safer sex practices and testing for sexually transmitted infections. Similar rising trends are reported for other sexually transmitted infections Halton Region Infectious Disease Report 22

25 Chlamydia in Halton Region Table 3: Number of reported chlamydia infections, by sex, Halton Region, Sex Females Males Total Since 2006, the number of chlamydia infections increased by 47% from 466 reported cases in 2006 to 684 reported cases in Females accounted for two-thirds of the total reported cases in 2009 (Table 3) Females Males Total Figure 13: Chlamydia, age-standardized rates, by sex, Halton Region, The age standardized incidence rates of chlamydial infections in Halton showed a rising trend between 2006 and 2009 (Fig. 13). This was true for females and males Halton Region Infectious Disease Report 23

26 Number of reported cases Age Group Figure 14: Chlamydia, number of reported cases, by age group, Halton Region, Increases in reported cases were noted for all age groups, with the age groups being most affected (Fig. 14). Over the four-year time period, between 2006 and 2009, the total number of cases amongst Halton teens aged 15 to 19 increased by 42% from 103 to 146. A 38% increase was noted in the number of cases amongst those aged (from 183 to 253) and 63% increase (from 89 to 145) in the cases aged 25 to 29 (Fig. 14) Halton Region Infectious Disease Report 24

27 180 Number of reported cases Age Group Figure 15: Chlamydia, number of reported cases, by age group, females, Halton Region, In Halton, the number of chlamydia infections in females increased by 55% from 292 reported cases in 2006 to 454 reported cases in Among females, during this 4 year time period, there was an overall increase of 37% in the age group, 42% in the age group and 66% in the age group (Fig. 15). In addition, in 2009, there were 87 cases in the 30 and older age group a 123% increase over Halton Region Infectious Disease Report 25

28 Std. Rate per 100, Age Group Figure 16: Chlamydia, age-specific incidence rates, by age group, females, Halton Region, Between 2006 and 2009, in Halton, the age-specific incidence rate for females aged increased from 40.9 cases per 100,000 to 48.3 per 100,000 teens (Fig. 16). For those aged 20-24, the age-specific incidence rate increased from 72.2 per 100,000 to 85.0 per 100,000 residents in that age group. And, the age-specific incidence rate amongst those aged increased from 36.5 per 100,000 to 54.6 per 100,000 adults in that age group Halton Region Infectious Disease Report 26

29 Number of reported cases Age Group Figure 17: Chlamydia, number of confirmed cases, by age group, males, Halton Region, In Halton, the number of chlamydia infections in males increased by 33% from 171 reported cases in 2006 to 227 reported cases in Among males, during this 4 year time period, there was an overall increase of 65% in the age group, 32% in the age group and 59% in the age group (Fig. 17). The number of cases in the in the 30 and older age group remained stable Halton Region Infectious Disease Report 27

30 Std. Rate per 100, Age Group Figure 18: Chlamydia, age-specific rates of incidence, by age group, males, Halton Region, Between 2006 and 2009, in Halton, the age-specific incidence rate for males aged increased from 7.7 cases per 100,000 to 10.9 per 100,000 teens (Fig. 18). For those aged 20-24, the age-specific incidence rate increased from 39.2 per 100,000 to 41.8 per 100,000 residents in that age group. And, the age-specific incidence rate amongst those aged increased from 31.2 per 100,000 to 40.3 per 100,000 adults in that age group. Chlamydia is the most commonly reported infection and, like other sexually transmitted infections, incidence continues to rise in both Halton Region and Ontario. Further investigation into the increasing rates needs to be conducted at both a local and provincial level. At the same time it will be important to target the age groups most affected by this infection in future health promotion and prevention campaigns and strategies Halton Region Infectious Disease Report 28

31 35 30 Proportion of total visits Burlington Halton Hills Milton Oakville Municipality Figure 19: Proportion of total reported cases of chlamydia, by municipality, Halton Region, On average, between 2006 and 2009, 32% of the cases were from Burlington, 28% from Oakville, 16% from Milton and 8% from Halton Hills (Fig. 19). Gonorrhoea In 2009, there were 63 cases of reported gonorrhoea infections, comprising 8% of all sexuallytransmitted infections. There were 53 reported cases on average per year in the previous five years (Fig. 20). Gonorrhoea, or gonococcal infection, is a sexually-transmitted bacterial disease, which differs in males and females in course, severity and ease of recognition. Worldwide, the disease affects both men and women, especially sexually active adolescents and younger adults. Prevalence is highest in communities of lower socioeconomic status. Untreated individuals may be infectious for months (Heymann, 2004). As in other locations, the majority of cases in Halton were in youth and young adults: 56% of cases were in those aged 15 to 24 years, and 84% were aged under 40 years Halton Region Infectious Disease Report 29

32 40.0 Std. Incidence Rate/100, Halton Year Ontario Figure 20: Gonorrhea, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario [Source: Reportable Disease Information System ( ), Integrated Public Health Information System ( ), Ministry of Health and Long-Term Care (2010).] Although Halton's gonorrhea rates continue to be consistently lower than Ontario, the age standardized incidence rates of gonorrhea increased for both Halton Ontario between 2000 and 2009, (Fig. 20). In Halton the increase was from 6.9 in 2000 to 14.6 cases per 100,000 people in 2009, or, an increase of 112%. Syphilis In 2009, there were 35 reported cases of syphilis in Halton Region. Of these, 6 cases were infectious and 29 non-infectious. On average, in the previous five year period, 11 cases of syphilis (all types) were reported to the Halton Region Health Department. Syphilis is a complex sexually transmitted infection characterized clinically by a primary lesion, a secondary eruption involving skin and mucous membranes, long periods of latency and later lesions of skin, bone, viscera, the central nervous system and cardiovascular system. All untreated cases will go on to a latent period of weeks to years, and one-third will then exhibit tertiary syphilis signs and symptoms. In the early years of latency, there may be recurrence of infectious lesions of the skin and mucous membranes. Syphilis is infectious mostly during the acute phases, and is non-infectious during most of the latent period. Fetal infection results in congenital syphilis and occurs with high frequency in untreated early infections of pregnant women (Heymann, 2004). Figure 21 shows the number of reported cases of syphilis, by type, in Halton Region in 2009 compared to the previous five-year annual averages Halton Region Infectious Disease Report 30

33 Number of Reported Cases Annual Average Syphilis - Total Syphilis - Infectious Syphilis - Non-infectious Figure 21: Number of cases of syphilis, Halton Region, 2009 compared to previous five-year annual average. [Source: Reportable Disease Information System ( ) and Integrated Public Health Information System ( ).] Infectious syphilis (primary, secondary and early latent states) is the least common of the nationally reportable sexually transmitted infections Halton Region Infectious Disease Report 31

34 14.0 Std. Incidence Rate/100, Halton Syphilis - Infectious Halton Syphilis - Non-infectious Ontario Syphilis - Infectious Ontario Syphilis - Non-infectious Figure 22: Infectious and non-infectious syphilis, age standardized incidence rates per 100,000 population, Halton Region compared to Ontario, Note: Ontario data for non-infectious syphilis prior to 2005 was not available at the time of writing of this report. Ontario data has not been adjusted to the new 2009 case classifications. [Source: Reportable Disease Information System ( ), Integrated Public Health Information System ( ), Ministry of Health and Long-Term Care (2010).] Halton s age standardized incidence rates of infectious syphilis fluctuated but showed a general increase over the 10-year period. The 2009 age standardized incidence rate was 1.3 cases per 100,000. These fluctuations are subject to the small number of reported cases on a year-to-year basis. In Ontario during this 10-year time period, infectious syphilis began to increase after 2001, from a rate of 0.2 cases per 100,000 population in 2001 to a rate of 5.7 cases per 100,000 in It needs to be noted that Ontario syphilis data has not been adjusted to the new 2009 case classifications. Non-infectious syphilis in Ontario showed a doubling in rates from 5.6 cases per 100,000 population in 2005 to 12.3 cases per 100,000 in 2006, followed by a slow decline (Fig. 23). In the past 10-year period, non-infectious syphilis in Halton reached a 10-year high incidence rate of 4.3 cases per 100,000 population in 2009 (Fig. 22). Newly diagnosed non-infectious syphilis is found primarily through screening and the higher rates of non-infectious disease may reflect increased screening. While cases of non-infectious 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 Halton Region Infectious Disease Report 32

35 Selected Blood-borne Infections Blood-borne infections are those which can be transmitted by direct contact with blood or bodyfluids, or by organ transplants involving infected organs, and also include some diseases which are transmitted by unprotected sex or injection drug use. In the past these infections were also spread by blood transfusions; now blood donor screening prevents almost all such cases in which the agent is known and for which a test is available and being used. All reportable blood-borne infections can lead to a state where the body becomes permanently or persistently infected, and the micro-organism can be found in the blood and other body fluids over long periods of time. Understanding the epidemiology of blood-borne infections is particularly important for those infections that can be prevented by vaccination. The World Health Organization would like all children vaccinated to prevent hepatitis B infection (Heymann, 2004). This would ultimately eliminate the infection. In Ontario, hepatitis B vaccine has been routine for 12-year-olds since It is also provided to infants born to infected mothers and to other high risk groups. In 2009, 160 Halton residents were diagnosed with a reportable blood-borne infection, accounting for 9% of the total cases of reportable infectious diseases/infections that year. Figure 23 shows the number of new cases of selected blood-borne infections in Halton Region in 2009 compared to the previous five-year annual averages. 140 Number of Reported Cases Annual Average Hepatitis C Hepatitis B - carriers Hepatitis B - cases Disease Figure 23: The number of selected blood-borne infections, Halton Region, 2009 compared to previous 5- year annual average. [Source: Reportable Disease Information System ( ) and Integrated Public Health Information System ( ).] 2009 Halton Region Infectious Disease Report 33