Monthly Infectious Diseases Surveillance Report

Transcription

1 July 2012 Monthly Infectious Diseases Surveillance Report VOLUME 1, ISSUE 8 The is produced by Public Health Ontario (PHO) for the public health community of Ontario. We anticipate that the report will evolve over time according to our users needs and following a formal evaluation in We welcome feedback by to SurveillanceServices@oahpp.ca. Further information on the and past issues are available online at: In this issue: INFECTIOUS DISEASE IN FOCUS Chlamydia SIGNIFICANT REPORTABLE DISEASE ACTIVITY INFECTIOUS DISEASE ACTIVITY IN OTHER JURISDICTIONS Human Immunodeficiency Virus (HIV) Home Test Kits approved by FDA TELEHEALTH REPORT Fever/ILI Telehealth Gastrointestional (GI) Telehealth Respiratory Telehealth ONTARIO OUTBREAK REVIEW ENHANCED SURVEILLANCE DIRECTIVES (ESD) DISCONTINUED IN JUNE REFERENCES APPENDIX REPORTABLE DISEASES GLOSSARY Infectious Disease in Focus CHLAMYDIA Chlamydia is the most frequently reported reportable disease in Ontario. Chlamydia infections are caused by various serotypes of Chlamydia trachomatis (C. trachomatis) bacteria, which can infect mucous membranes of the urethra, cervix, vagina, oropharynx, rectum and conjunctiva. It is transmitted mainly through sexual contact, including oral, vaginal or anal intercourse. Less commonly, infected pregnant females can transmit the bacteria to their children during birth (vertical transmission). Individuals with chlamydia can either be symptomatic or asymptomatic; up to 70% of females and 50% of males may not experience any symptoms while infected (asymptomatic). 1,2 The time from exposure to C. trachomatis to the development of symptoms is typically 7 to 14 days but can be as long as 6 weeks. 1,3 If symptoms are present, they may include unusual vaginal discharge or bleeding, painful urination, pain and/or vaginal bleeding during or after vaginal intercourse and lower abdominal pain among women, and urethral

2 irritation, itching or penile discharge among men. 3 Individuals with rectal chlamydia may experience rectal bleeding, discharge and pain 4. Left untreated, chlamydia infections are associated with long term complications, which may also be asymptomatic. In females, the bacteria can spread to other reproductive organs such as the fallopian tubes, which may result in chronic pelvic pain, pelvic inflammatory disease (PID), ectopic pregnancy, or infertility. 1 In males, untreated infections may lead to epididymo-orchitis, which causes pain, fever, and in some cases, sterility. In rare cases, chlamydia infections can lead to Reiter s syndrome in both males and females, causing arthritis, skin lesions and inflammation of the eye. 4 Untreated chlamydia during pregnancy may also lead to premature delivery. 4 In cases of vertical transmission during the perinatal period, chlamydia can result in eye infections (opththalmia neonatorum) in neonates and pneumonia in infants less than 6 months of age. 1,4 Individuals infected with chlamydia, whether symptomatic or asymptomatic, are considered infectious and can transmit the bacteria to others until appropriate treatment has been received. Following successful treatment, susceptibility to chlamydia exists as long as high risk behaviours continue. Risk factors include sexual contact with a person who has a symptomatic or asymptomatic chlamydial infection, sexual activity under the age of 25 years, and having a new partner or multiple partners in the past year. 3,5 Chlamydial infections, like other sexually transmitted infections (STIs), enhance sexual transmission of HIV. 3 Biologically, young females are more susceptible to chlamydia infections due to their immature cervix and are considered high risk for infection if they are sexually active. 4 In 2011, 36,346 confirmed cases of chlamydia were reported in Ontario - the highest reported number of cases in the past decade. Over the past ten years, the reported incidence rate of chlamydia in Ontario increased by approximately 79%, from a rate of 152 cases per 100,000 population in 2002 to 272 cases per 100,000 population in 2011 (Figure 1). Compared to Ontario, the Canadian rate for chlamydia has been consistently higher and has demonstrated a similar trend over time, increasing from 180 cases per 100,000 population in 2002 to 259 cases per 100,000 population in 2009, a 44% increase. 6 Page 2 of 13

3 Figure 1. Reported incidence of chlamydia in Ontario and Canada: , Number of cases 35,000 30,000 25,000 20,000 15,000 10,000 5, Rate per 100,000 population Episode year 0 Cases Ontario rate Canadian rate Sources: Ontario data Ontario Ministry of Health and Long-Term Care, integrated Public Health Information System (iphis) database, extracted by PHO [2012/05/30]. Ontario population data Ontario Ministry of Health and Long-Term Care, IntelliHEALTH Ontario, extracted by PHO [2012/03/15]. Canadian data Public Health Agency of Canada. Reported cases and rates of chlamydia by province/territory and sex, 1991 to In Ontario, 65% of chlamydia cases (23,482/36,346 cases) reported in 2011 were among females and the highest reported incidence rates were observed in the 20 to 24 age groups for both males and females. These high rates equate to approximately 1% of males (1,003 cases per 100,000 population) and nearly 2% of females (1,963 cases per 100,000 population) in the 20 to 24 age group reporting a chlamydia infection, assuming a single infection for each individual. Females aged 15 to 19 also had a high reported incidence, equating to 1.5% (1,498 cases per 100,000 population) of this population reporting an infection. Where reported, the most commonly reported risk factor across all age groups was no condom used. In 2011, 67% of cases reported a risk factor; of these, 75% (18,380/24,368) reported no condom used. All 36 health units reported cases of chlamydia in 2011 with reported incidence rates ranging from 145 to 646 cases per 100,000 population. The greatest number of cases were reported by the City of Toronto, Peel Region and City of Ottawa health units, while the highest reported incidence rates were observed among northern health units. In 2011, the highest rates were observed in Northwestern (646 cases per 100,000 population), Porcupine (478 cases per 100,000 population) and Thunder Bay District (460 cases per 100,000 population) health units (Map 1). Page 3 of 13

4 Map 1. Reported incidence rates of chlamydia by diagnosing health unit: Ontario, 2011 Source: Ontario Ministry of Health and Long-Term Care, integrated Public Health Information System (iphis) database, extracted by PHO [2012/05/30]. Ontario population data Ontario Ministry of Health and Long-Term Care, IntelliHEALTH Ontario, extracted by PHO [2012/01/13]. The cause of the increasing trend in the incidence of chlamydia in Ontario has not been fully explained. Increases may be partly explained by changes in screening practices. For example, Canadian and American guidelines have recommended routine screening of high risk groups which has led to increased testing. 3,4 Similarly, advances in testing methods which are more sensitive, simpler, less invasive and more acceptable to patients (e.g. urine test) may have also resulted in increased testing. Despite the increasing trend, chlamydia is still underreported in part due to the large proportion of asymptomatic cases. 3 As such, further analyses are required to estimate the true burden of chlamydia and to determine the degree to which increased testing and increased transmission, including reinfection, have each contributed to the observed increase in reported chlamydia cases in Ontario. Individual and population-based prevention measures are available for the control of chlamydia and for the prevention of chlamydia-associated complications. Condom use during sexual activity reduces the risk of chlamydia transmission. Early diagnosis and appropriate treatment along with abstinence from unprotected sexual activity until all regular partners have been treated also reduces the risk of transmission and re-infection. At the population level, education focusing on safe sex practices is one component of prevention. 1 The availability of easily accessible screening for individuals at increased risk of chlamydia infection is a common prevention strategy to reduce transmission, along with counselling Page 4 of 13

5 and appropriate evidence-based approaches to case and contact management. 3 Individuals with high risk behaviours should be screened for re-infection with C. trachomatis six months after treatment. 3 Screening for C. trachomatis for pregnant women to prevent chlamydia infections in newborns is also recommended. 3 In Ontario, the Sexual Health and Sexually Transmitted Infections Prevention and Control Protocol makes provisions for the screening, diagnosis, treatment, and counselling of priority populations and cases and contacts of sexually transmitted infections. 5 Although chlamydia is a common STI, it is treatable and preventable. Significant Reportable Disease Activity From January 1 to May 31, 2012, case counts for salmonellosis, pertussis and chlamydia were significantly higher than expected compared to the year-to-month counts for 2010 and An overview of these diseases is not provided in this issue of the monthly report. In the case of chlamydia, which is covered in the In Focus section starting on page one, the increase is ongoing and is being monitored The increase in salmonellosis and pertussis are due to outbreaks which have been described in issues 4 to 7 of this report. Appendix 1 contains the year-to-date confirmed case counts for reportable diseases including salmonellosis, pertussis and chlamydia for 2012 compared to 2011 and Infectious Disease Activity in Other Jurisdictions This section of the report provides a snapshot of current activity related to infectious diseases across Canada and/or globally. The items included in this section are selected based on ongoing or potential impact on public health in Ontario. HUMAN IMMUNODEFICIENCY VIRUS (HIV) HOME TEST KITS APPROVED BY FDA The US Food and Drug Administration (FDA) has approved the first over-the-counter rapid test which allows individuals to test themselves for HIV. The US Centers for Disease Control and Prevention estimates that approximately 20% of the 1.2 million people in the US living with HIV are unaware that they are infected. By providing another testing option for individuals, health officials hope to reduce the number of new HIV infections every year from people who are unaware of their HIV status and enable treatment for those who would have otherwise remained undiagnosed. alspmas/ucm htm Editor s Note: According to the Public Health Agency of Canada, at the end of 2008, an estimated 65,000 people were living with HIV (including AIDS) in Canada. Of these, approximately 16,900, or 26%, were not aware of their infection. Currently, the HIV test kit has not been authorized for home use in Canada. Page 5 of 13

6 Telehealth Report Telehealth Ontario is a toll-free nursing helpline available to all residents of Ontario 24 hours a day, 7 days a week. PHO conducts surveillance using Telehealth call data that has been categorized into three syndromes: Gastrointestinal (GI), Fever/Influenza-like illness (ILI), and Respiratory (which includes both upper and lower respiratory symptoms). Data are utilized to determine whether observed call volumes are greater than statistically expected and to identify significant clusters of targeted syndromes. Significant geo-temporal clusters (detected using SaTScan) and/or temporal aberrations (detected using the Early Aberration Reporting System [EARS]) are communicated through the Public Health Ontario Portal and directly to the affected health unit(s) when they occur. Aberrations in Telehealth data may precede future case identification and outbreak activity, serving as a potential early warning system for these phenomena *. More information can be found in the Glossary. In June 2012, two geographically distinct respiratory clusters (Table 1) were identified among Telehealth calls. Five EARS flags indicating increases above the expected call volume were also identified. The increases pertained to the Fever/ILI syndrome which was observed three times in the month of June and the Respiratory syndrome which was observed twice in the month of June (Figures 2 and 4, respectively). Table 1. Significant Fever/ILI, Gastrointestinal (GI), and Respiratory syndrome clusters identified by SaTScan in June 2012 Cluster # FSAs in the Health Units Rad Cluster FSA Type cluster Affected (km) Obs Exp Obs/exp p Fever / No Fever/ILI clusters identified ILI GI No GI clusters identified Resp May 28 to P1L 32 HKPR, SMD, June 3* YRK, NPS May 29 to P1L 32 HKPR, SMD, June 4* YRK, NPS May 30 to P0B- 30 HKPR, SMD, June 5* 1 YRK, NPS June 8 to June 14 L2A 62 NIA, HAM, HDN, HAL, PEEL, TOR Obs = Observed count, Exp = Expected count, FSA = Forward sortation area, Km = Kilometre Source: Ontario Ministry of Health and Long-Term Care, Telehealth Ontario, extracted by Public Health Ontario [2012/07/04]. *Identified Respiratory cluster that represents a single event that remained significant for three consecutive days. * Evidence on the use of Telehealth to flag outbreaks is limited; however this information is being provided in order to present full disclosure of information available to Public Health Ontario Page 6 of 13

7 FEVER/ILI TELEHEALTH For the month of June 2012, no Fever/ILI syndrome clusters were identified (Table 1). However, three Fever/ILI EARS flags were generated on June 11, 12, and 21, indicating an increase in the volume of calls associated with the Fever/ILI syndrome compared to a rolling seven-day average (Figure 2). Figure 2. Fever/ILI syndrome calls: June 1-30, Source: Ontario Ministry of Health and Long-Term Care, Telehealth Ontario, extracted by Public Health Ontario [2012/07/04]. Page 7 of 13

8 GASTROINTESTIONAL (GI) TELEHEALTH No GI syndrome clusters or GI EARS flags were identified in the month of June 2012 (Table 1 and Figure 3). Although there were a number of days for which the Telehealth call volumes related to this syndrome were above the rolling seven-day average, they did not achieve statistical significance. Figure 3. Gastrointestinal syndrome calls: June 1-30, Source: Ontario Ministry of Health and Long-Term Care, Telehealth Ontario, extracted by Public Health Ontario [2012/07/04]. Page 8 of 13

9 RESPIRATORY TELEHEALTH Two distinct respiratory clusters were detected in June 2012 (Table 1). The first cluster was initially identified among calls made from May 28 to June 3 in Haliburton-Kawartha-Pine Ridge District, Simcoe- Muskoka District, York Region and North Bay-Parry Sound District health units. This cluster remained significant for three consecutive days up to June 5. The second cluster was detected among calls made from June 8 to June 14. This cluster was observed in Niagara Region, City of Hamilton, Haldimand- Norfolk, Halton Region, Peel Region and Toronto health units (Table 1). Two respiratory EARS flags were generated on June 9 and 17, indicating significant increases in Telehealth call volume related to the respiratory syndrome (Figure 4). Figure 4. Respiratory syndrome calls: June 1-30, Source: Ontario Ministry of Health and Long-Term Care, Telehealth Ontario, extracted by Public Health Ontario [2012/07/04]. Page 9 of 13

10 Ontario Outbreak Review The review of outbreaks section provides the total number of institutional respiratory infection outbreaks for the influenza season (Table 2). The number of outbreaks during the same period for the and influenza seasons are also presented for comparison. Table 2. Total number of institutional respiratory infection outbreaks for surveillance season to week 25, Ontario. Total Number of Time period Confirmed Outbreaks Total confirmed respiratory infection outbreaks for the season 644 Total confirmed respiratory infection outbreaks for the season 969 Total confirmed respiratory infection outbreaks for the season 520 Sources: Ontario Influenza Bulletin - Surveillance Week 24 & 25 (June 10 - June 23, 2012); Surveillance Week 24 & 25 (June 12 - June 25, 2011); and Surveillance Week 24 & 25 (June 13 - June 26, 2010) Enhanced Surveillance Directives (ESD) Discontinued in June No enhanced surveillance directives were discontinued in June Page 10 of 13

11 References (1) Heymann DL, editor. Control of communicable diseases manual. 19th ed. Washington: American Public Health Association; (2) Zelin, J., Robinson, A.J., Ridgeway, G.L., Allason-Jones, E., Williams, P. (1995). Chlamydial urethritis in heterosexual men attending a genitourinary medicine clinic: prevalence, symptoms, condom usage and partner change. International Journal STD AIDS, 6(1): (3) Expert Working Group on the Canadian Guidelines on Sexually Transmitted Infections. Canadian guidelines on sexually transmitted infections. Rev ed. Ottawa, ON: Public Health Agency of Canada; (4) Centers for Disease Control and Prevention [cdc.gov]. Atlanta, GA: US CDC. Chlamydia CDC fact sheet; Page last reviewed: March 25, February 8 [cited: 2012 June 1]. Available from: (5) Ministry of Health and Long-Term Care. Sexual health and sexually transmitted infections prevention and control protocol. Toronto: Queen s Printer for Ontario; [cited: 2012, June 4]. Available from th_sti.pdf (6) Public Health Agency of Canada. Reported cases and rates of chlamydia by province/territory and sex, 1991 to 2009: 2011 February 22 [cited 2012 June 13]. Available from: Page 11 of 13

12 Appendix Reportable Diseases Appendix 1. Confirmed cases of reportable disease* by month: Ontario, Sources: Ontario Ministry of Health and Long-Term Care, integrated Public Health Information System (iphis) database, extracted [2012/06/15]. Population data obtained from IntelliHEALTH Ontario, retrieved by Public Health Ontario [2012/03/15]. Note 1: Rates presented in the table are per 100,000 population: year-to-date (YTD) and year-to-month (YTM). Note 2: Does not include cases in which the Ministry of Health and Long-Term Care was selected as the Diagnosing Health Unit or cases with a Disposition Description set to does not meet or entered in error. Note 3: Tuberculosis and AIDS case counts are based on diagnosis date and not episode date. HIV case counts are based on encounter date. Note 4: Differentials in year over year comparisons are reflective of changes in disease incidence and changes in the size of the population. Note 5: The case of rubella reported in January 2012, the case of rabies reported in April 2012 and the measles case reported in May 2012 were related to travel and were not acquired in Ontario. * Appendix 1 is not an exhaustive list of all reportable diseases in Ontario. Percent (%) difference is calculated using unrounded rates; numbers displayed in these columns may vary from calculations using rounded rates. ** For 2010, influenza counts include the influenza A (H1N1) pdm09 counts, in addition to seasonal influenza A, B, and A & B. As influenza A (H1N1)pdm09 aggregate reporting occurred on a weekly basis, the week in which more days belonged to a particular month was counted in that month.

13 Glossary Early Aberration Reporting System (EARS) Software from the U.S. Centers for Disease Control and Prevention (CDC) designed for aberration detection using public health surveillance data. EARS uses three limited baseline aberration detection methods (based on a positive 1-sided CUSUM calculation) and produces three types of statistically marked aberrations, or flags, when the observed values are greater than statistically expected (details below). More information on EARS can be found at C1 (mild) Lowest sensitivity EARS flag. The baseline period for C1-MILD is obtained from the previous 7 days in closest proximity to the current value. Therefore, when this flag is produced on a particular day, the next day is less likely to produce a flag because the elevated count from the previous day will be incorporated into the new baseline period. C2 (medium) EARS flag that uses a 7-day baseline period, but with 2-days lag between the baseline and the current day. For example, on the 10th day of surveillance the baseline data will be from day 1 to day 7. This flag is more likely to note high consecutive values, because they are not immediately incorporated into the baseline period as for C1 flag. C3 (ultra) Highest sensitivity EARS flag. Uses the baseline period as the C2-MEDIUM, but the threshold is based on a 3-day average run length of the one-sided positive CUSUM. It is useful for identifying aberrations that gradually increase over short periods of time. SaTScan Software that analyzes geospatial and temporal data using space-time scan statistic. It utilizes thousands or millions of overlapping cylinders to define the scanning window with its base representing the geographical area of a potential outbreak and its height representing the number of days. For each cylinder the observed/expected ratio is calculated and the most likely cluster is identified, along with secondary clusters. More information on SaTScan can be found at Page 13 of 13