EPIDEMIOLOGY OF HEPATITIS C INFECTION IN ONTARIO, 2010 Robert R. Remis MD, MPH, FRCPC, Juan Liu MSc Ontario HIIV Epidemiologic Monitoring Unit, University of Toronto prepared for AIDS Bureau, Ontario Ministry of Health and Long-Term Care December 2011
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EPIDEMIOLOGY OF HEPATITIS C INFECTION IN ONTARIO, 2010
Robert R. Remis MD, MPH, FRCPC, Juan Liu MSc Ontario HIIV Epidemiologic Monitoring Unit, University of Toronto
prepared for
AIDS Bureau, Ontario Ministry of Health and Long-Term Care
December 2011
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TABLE OF CONTENTS 1 INTRODUCTION……………………………………………………………….………... 6 2 METHODS………………………………………………………………….……………. 7 2.1 Reported cases of hepatitis C, Ontario …………………………………….………. 7 2.1.1 Source of data……………………………………………………………….. 7 2.1.2 Data analysis………………………………………………………………... 7 2.2 Acute and chronic hepatitis C, EHSSS……………………………………………... 8 2.2.1 Source of data……………………………………………………………….. 8 2.2.2 Data analysis………………………………………………………………... 8 2.3 Ontario HCV model………………………………………………………………... 9 3 RESULTS………………………………………………………………………………… 9 3.1 Reported cases of hepatitis C, Ontario………………………………….........…….. 9 3.2 Acute and chronic hepatitis C, EHSSS…………….……………………………….. 11 3.3 Ontario HCV model………………………………………………………………... 13 4 DISCUSSION…………………………………………………………………………….. 15 REFERENCES…………………………………………………………………………… 17 LIST OF TABLES AND FIGURES……………………………………………………... 3
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LIST OF TABLES AND FIGURES Section One Table 1.1 Number and rate (per 100,000 population) of reported cases of hepatitis C,
Ontario, 1992-2010 Table 1.2 Reported cases and rates of hepatitis C by year and sex, Ontario, 2005 to 2010 Table 1.3a Number and proportion of reported cases and rate of hepatitis C by age and sex,
Ontario, 2005 Table 1.3b Number and proportion of reported cases and rate of hepatitis C by age and sex,
Ontario, 2006 Table 1.3c Number and proportion of reported cases and rate of hepatitis C by age and sex,
Ontario, 2007 Table 1.3d Number and proportion of reported cases and rate of hepatitis C by age and sex,
Ontario, 2008 Table 1.3e Number and proportion of reported cases and rate of hepatitis C by age and sex,
Ontario, 2009 Table 1.3f Number and proportion of reported cases and rate of hepatitis C by age and sex,
Ontario, 2010 Table 1.4a Number and proportion of reported cases and rate of hepatitis C by public health
unit and sex, Ontario, 2005 Table 1.4b Number and proportion of reported cases and rate of hepatitis C by public health
unit and sex, Ontario, 2006 Table 1.4c Number and proportion of reported cases and rate of hepatitis C by public health
unit and sex, Ontario, 2007 Table 1.4d Number and proportion of reported cases and rate of hepatitis C by public health
unit and sex, Ontario, 2008 Table 1.4e Number and proportion of reported cases and rate of hepatitis C by public health
unit and sex, Ontario, 2009 Table 1.4f Number and proportion of reported cases and rate of hepatitis C by public health
unit and sex, Ontario, 2010
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Table 1.5 Number and proportion of reported hepatitis C case by year, risk factor and sex, Ontario 2007-2009
Table 1.6 Number and proportion of reported hepatitis C case by year, risk factor and health
region, Ontario 2007-2009 Figure 1.1 Number and rate of reported cases of hepatitis C, Ontario, 1992 to 2010 Figure 1.2 Proportion of reported HCV cases by age, Ontario, 2005 to 2010 Figure 1.3 Rate (per 100,000 population) of reported HCV cases by age, Ontario, 2005 to
2010 Figure 1.4 Proportion of reported HCV cases by health region, Ontario, 2005 to 2010 Figure 1.5 Rate (per 100,000 population) of reported HCV cases by health region, Ontario,
2005 to 2010 Section Two Table 2.1 Number and rate (per 100,000 population) of reported HCV cases by site, year of
diagnosis, stage of HCV and sex, EHSSS, Ontario, 2007 to 2010 Table 2.2a Cumulative number and proportion of reported HCV cases by age group, stage of
HCV and sex, Ottawa, Ontario, 2007 to 2010 Table 2.2b Cumulative number and proportion of reported HCV cases by age group, stage of
HCV and sex, Hamilton, Ontario, 2007 to 2010 Table 2.2c Cumulative number and proportion of reported HCV cases by age group, stage of
HCV and sex, London, Ontario, 2007 to 2010 Table 2.3 Annual rate (per 100,000 population) of reported HCV cases by age group, site,
and sex, EHSSS, Ontario, 2007 to 2010 Table 2.4a Cumulative number and proportion of reported HCV cases by risk factor, stage of
HCV and sex, Ottawa, Ontario, 2007 to 2010 Table 2.4b Cumulative number and proportion of reported HCV cases by risk factor, stage of
HCV and sex, Hamilton, Ontario, 2007 to 2010 Table 2.4c Cumulative number and proportion of reported HCV cases by risk factor, stage of
HCV and sex, London, Ontario, 2007 to 2010
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Table 2.5a Cumulative number and proportion of reported HCV cases by region of birth, stage of HCV and sex, Ottawa, Ontario, 2007 to 2010
Table 2.5b Cumulative number and proportion of reported HCV cases by region of birth,
stage of HCV and sex, Hamilton, Ontario, 2007 to 2010 Table 2.5c Cumulative number and proportion of reported HCV cases by region of birth,
stage of HCV and sex, London, Ontario, 2007 to 2010 Table 2.6a Cumulative number and proportion of reported HCV cases by race/ethnicity,
stage of HCV and sex, Ontario, 2007 to 2010 Table 2.6b Cumulative number and proportion of reported HCV cases by race/ethnicity,
stage of HCV and sex, Ontario, 2007 to 2010 Table 2.6c Cumulative number and proportion of reported HCV cases by race/ethnicity,
stage of HCV and sex, Ontario, 2007 to 2010 Section Three Table 3.1a Modeled HCV prevalence (number and rate) by place of birth, sex and exposure
category, Ontario, 2007 Table 3.1b Modeled HCV prevalence (number and rate) by place of birth and exposure
category, Ontario, 2007 Table 3.2 Modeled HCV incidence (number and rate) by place of birth, sex and exposure
category, Ontario, 2007 Table 3.3 Modeled HCV prevalence by public health unit and health region, both sexes,
Ontario, 2007 Table 3.4 Modeled incidence of HCV sequelae, by five-year interval, Ontario, 1967 to 2027 Table 3.5 Modeled prevalence of HCV sequelae, by five-year interval, Ontario,
1967 to 2027
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1. INTRODUCTION Hepatitis C virus (HCV) was first identified in 1989 <1> and is transmitted primarily through parenteral exposure (i.e. blood-borne). Sexual transmission almost certainly occurs but its public health importance is not well quantified. HCV-infected persons can remain asymptomatic for many years following initial infection. HCV is a major cause of acute hepatitis and chronic liver disease, including cirrhosis, liver cancer and decompensated liver failure. Hepatitis C is largely preventable. It is not spread through casual contact and the risk of sexual transmission is low compared to HIV and hepatitis B. In most West industrialized countries, injection drug use is the predominant risk factor for HCV acquisition, due to sharing needles, syringes and other injection equipment. Prior to the implementation of routine HCV screening of plasma and blood donors in 1990, contaminated clotting factors and blood transfusion accounted for 15-20% of HCV infections. The current risk of HCV transmission via blood transfusion is estimated to be less than 1 per 500,000 units <2>. Other potential risk factors include: sharing of other drug-related equipment (e.g. crack pipes, straws, cookers, spoons, etc.), sharing of personal hygiene items with an HCV-infected person (e.g. razors, scissors, nail clippers, toothbrush), tattooing or body piercing with contaminated equipment, and medical or dental practices involving the use of contaminated equipment. Sexual (e.g. unprotected sex with an infected partner that includes contact with blood or exchange of blood) and mother-to-child transmission can also occur but are uncommon. The HCV serologic test was first licensed in 1990. However, diagnostic testing on a broad scale did not occur until the mid-1990s when HCV infection became reportable disease in most Canadian provinces. As of 1998, in all Canadian provinces, reporting hepatitis C diagnoses to local public health units was mandatory. In 2003, under contract with Hepatitis C Program, Health Canada, Remis carried out a modeling study to model HCV incidence, prevalence and sequelae to 2002 in Canada <3>. In 2006, under a mandate from the Ontario Hepatitis Secretariat, Ontario Ministry of Health and Long-Term Care (OMHLTC), the research team refined the modeling methods and adapted them to evaluate HCV epidemiology in Ontario. As of December of 2004, they estimated that approximately 110,000 persons in Ontario were infected with HCV. 53% were injection drug users, 13% had been infected through blood transfusion and 34% by other modes of transmission <4>. The Ontario model was later updated to 2007 <5>. The present report presents the modeled HCV incidence and prevalence to 2007, reported HCV cases to the Ontario reportable disease surveillance system from 2007 to 2010, and HCV cases diagnosed from 2007 to 2010 evaluated by the Enhanced Hepatitis Strain Surveillance System (EHSSS) operated by the Public Health Agency of Canada (PHAC).
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2. METHODS
2.1 Reported hepatitis C cases, Ontario
2.1.1 Source of data Hepatitis C has been reportable in Ontario since October 1991. The current case definition requires confirmation of a positive anti-HCV antibody result using two enzyme-linked immunoassay (EIA) laboratory tests. If the antibody result is confirmed positive, the case is forwarded to local public health units for investigation and follow-up in accordance with the Ontario Public Health Standards, 2008 <6>. Case definitions in Canada, including Ontario, do not distinguish between acute and chronic HCV infections. Duplicates are removed at data entry when the identifying information of a new matches perfectly or almost perfectly a case previously entered. Case data is collected by the 36 public health units in Ontario and transmitted regularly to the OMHLTC. Obvious duplicates are identified and removed at the provincial level <4>. The Public Health Division, MOHLTC extracted data on reported hepatitis C cases from the integrated Public Health Information System (iPHIS) database and provided us with custom tables on the number of reported hepatitis C cases by age, sex and year and by public health unit, sex and year from 2005 to 2010. Risk factor data were incompletely collected after 2005. Given the lack of clear scientific evidence for transmission efficiency for some potential risk factors, it was difficult to develop a hierarchy mutually exclusive algorithm for risk factors and the classification of exposure category may not be fully validated for some cases. 2.1.2 Data analysis For each year from 2007 to 2010, we prepared two tables: 1) number, proportion and incidence rate per 100,000 of hepatitis C by age group and sex, and 2) number, proportion and incidence rate per 100,000 of hepatitis C by public health unit/health region and sex. We also present the number and proportion of reported hepatitis C case by year, exposure category and sex from 2007 to 2009. To calculate annual incidence, we used populations by year, sex, age group and public health unit obtained from Statistics Canada.
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2.2 Acute and chronic hepatitis C cases, EHSSS
2.2.1 Source of data
To obtain a more accurate assessment of hepatitis B and C infection in Canada, the EHSSS was initiated in 1998 in four health regions in Canada, including Ottawa. Since 2006, Hamilton and London, Ontario have joined the system and contribute data on newly identified acute and chronic hepatitis B and hepatitis C infections, as well as risk factors associated with these infections. The methodology of EHSSS, case definition and classification of exposure category have been described in detail in reports published by the investigators <7, 8>. Briefly, an acute HCV infection is defined as: seroconversion from negative HCV antibody (ant-HCV) to positive anti-HCV in 12 months, and/or evidence of clinical hepatitis C requiring the satisfaction of both clinical and laboratory criteria. Clinical criteria include an acute illness with a discrete onset of symptoms. Laboratory criteria include laboratory confirmation of HCV infection and elevated serum aminotransferase levels, excluding other causes of acute hepatitis. A case which does not meet the above definition for a confirmed acute case but has laboratory evidence of HCV infection (e.g. confirmed anti-HCV positive) is classified as a chronic HCV case. A case confirmed as infected but which could not be determined to be acute or chronic is referred to as ‘indeterminate’ <7, 8>. Risk factor information at six months before the onset of the infection for acute cases and lifetime risk factor information for chronic cases are collected from persons who consent and are interviewed. Cases who reported more than one risk factor for infection during the exposure period are assigned to a risk group based on a mutually exclusive hierarchy which has been previously described <7, 8>. The EHSSS provided us data on newly diagnosed acute and chronic hepatitis C infections reported in Ottawa from 1998 to 2010 and in Hamilton and London from 2006 to 2010. For the purpose of this report, we present data from 2007 to 2010 for all three sites. 2.2.2 Data analysis
For each site in Ontario participating from 2007 to 2010, we prepared four tables: 1) cumulative number and proportion of reported HCV cases by age group, stage of HCV and sex, 2) cumulative number and proportion of reported HCV cases by risk factor, stage of HCV and sex, 3) cumulative number and proportion of reported HCV cases by region of birth, stage of HCV and sex, and 4) cumulative number and proportion of reported HCV cases by race/ethnicity, stage of HCV and sex. In this report, we present the annual rate of reported HCV cases using 2007 to 2010 population estimates for each site as the denominator. We also present the annual rate or reported HCV cases by age group using 2006 census population by age for each site as the denominator.
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2.3 Ontario HCV model Remis derived estimates of HCV infection and its sequelae in Ontario using an actuarial model originally developed for the Canada as a whole in 2003 as noted above <3>. Estimates of prevalence-related counts were calculated as of December 2007 and incident events were calculated for the calendar year 2007. A detailed description of the methodology used in the Canadian study is summarized in Appendix A of the previous report <4>. The adaptation of the method to Ontario involved determining the characteristics of the Ontario population from census and immigration data, obtaining updated information on the epidemiology of hepatitis C in Ontario and updating the information on the progression of hepatitis C infection through its clinical stages, including complications (cirrhosis, decompensated liver failure and hepatocellular carcinoma), liver transplant and hepatitis C-related mortality. The detailed methodology used to derive the estimates in Ontario was described in the previous report <4>. 3. RESULTS 3.1 Reported hepatitis C cases, Ontario
Table 1.1 presents the number and rate (per 100,000 population) of hepatitis C cases reported in Ontario from 1992 to 2010. Overall, 97,392 cases have been reported over this 19-year period. The annual number of reported cases increased after HCV reporting began and peaked in 1996, with 7,782 cases. A decreasing trend has been observed since then. About 4,500 new cases have been reported annually in the most recent six years from 2005 to 2010. The rate of reported HCV cases increased from 16.3 per 100,000 population in 1992 to a peak of 70.2 in 1996, then gradually decreased and has remained stable at about 32-36 per 100,000 population from 2005 to 2010. Figure 1.1 shows graphically the annual number and rate of reported HCV cases in Ontario from 1992 to 2010. Table 1.2 presents the number and rate of reported HCV cases by sex from 2005 to 2010. Overall, 26,812 cases were reported during this six-year period. 62% of the reported cases were male. There was no obvious trend during this period, overall or by sex. The annual incidence rate was almost twice as high in males (40-48 per 100,000) as in females (23-29 per 100,000). Table 1.3a to Table 1.3f present the annual number, proportion and rate of reported HCV cases by age group and sex from 2005 to 2010. In all years and in both sexes, the majority of reported HCV cases were among persons 25-54 years of age and the highest rate of HCV was among persons 45-54 years of age. Figures 1.2 and 1.3 show the proportion and rate, respectively, of HCV cases by age group for both sexes together. The proportion of reported HCV cases among persons aged 15-24, 25-34,
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and 55-64 years significantly increased and the proportion of reported HCV cases among persons aged 35-44 years significantly decreased over the six-year period. An increase in the annual rate was observed among persons 15-24 years of age, from 14.6 per 100,000 population in 2005 to about 20 per 100,000 in 2008-10 and persons 55-64 years of age from 30.5 per 100,000 in 2005-06 to 46.6 per 100,000 in 2010. The annual rate decreased among persons aged 35-44 and 45-54 years from 2005 to 2010. Table 1.43a to Table 1.4f present the number, proportion and rate of hepatitis C cases by public health unit/health region and sex for each year from 2005 to 2010. The greatest number of cases was reported from the Toronto and Central East, other health regions. Generally, the rate of HCV cases among males was higher than among females regardless of public health unit and year of report. The overall annual rate varied by public health unit, from the highest in Kingston-Frontenac-Lennox-Addington (about 90-130 per 100,000) and Thunder Bay (about 80-100 per 100,000), intermediate in Algoma and Haliburton-Kawartha-Pine Ridge (about 50-60 per 100,000), to the lowest in the Huron and Perth public health units (less than 20 per 100,000). Figures 1.4 and 1.5 show the proportion and rate of HCV cases by health region from 2005 to 2010. Toronto case counts appeared to be decreasing whereas Southwest and Central West health regions appeared to increase in the proportion of reported HCV cases from 2005 to 2010. The annual rate of HCV cases in Southwest region increased from 28.2 per 100,000 population in 2005 to 41.5 per 100,000 in 2010, while the annual rate of HCV cases in Toronto and Eastern, other regions appeared to be decreasing. Table 1.5 presents the number and proportion of reported HCV cases by exposure category and sex from 2007 to 2009 (data on risk factors were available only for this period). The information on risk factors was not available for a significant proportion of cases: 48% of cases in 2007 and 38% in both 2008 and 2009 had no data on risk factors. From the available data on risk factors, the majority of HCV cases were injection drug users and 11-14% were persons who received blood transfusion or clotting factors in Canada prior to the implement of routine HCV screening of plasma and blood donors in 1990 or had unknown date of blood transfusion or received blood transfusion outside Canada. Persons infected by other routes of transmission accounted for about 22-30%. Table 1.6 presents the number and proportion of reported HCV cases by exposure category and health region from 2007 to 2009. Except for Ottawa, one-third to half of cases in the each health region had no data on risk factors. From the available data on risk factors, 80% of reported HCV cases in the Northern region were IDU. In contrast, about 40% of cases in the Central East, other region and 50% of cases in Toronto were IDU. IDUs comprised 60-70% of cases in the other health regions.
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3.2 Acute and chronic hepatitis C cases, EHSSS Table 2.1 presents the number and annual rate (per 100,000 population) of reported hepatitis C cases by site, year of diagnosis, stage of HCV infection and sex from 2007 to 2010. The cumulative number of HCV infections for the four years was 1,031 cases in Ottawa, 715 in Hamilton, and 419 in London. For acute HCV cases, the numbers were: 119 in Ottawa, 32 in Hamilton, and 57 in London. Annual rates of HCV infection were generally slightly higher in Hamilton than in Ottawa and London. However, they were relatively stable over the four years in the three sites, with 25-34 cases per 100,000 person-year in Ottawa, 31-37 in Hamilton, and 21-33 in London. Rates in males were higher than in women with an M:F ratio of 1.4 to 2.2. Tables 2.2a, 2.2b and 2.2c present the cumulative number and proportion of reported HCV cases by age group, stage of HCV and sex from 2007 to 2010 for Ottawa, Hamilton and London, respectively. In Ottawa, the majority (79.1%) of reported HCV cases were in persons aged 25 to 59 years, 83.2% in males and 72.4% in females. In both sexes, acute HCV cases were significantly younger than chronic HCV cases (all p<0.0001). Overall, 75.6% of acute HCV cases were in persons aged 15-39 years, compared to 24.2% of chronic HCV cases which were in this same age group. In Hamilton, the majority (85.4%) of reported HCV cases were in persons aged 25 to 59 years, 87.9% in males and 80.8% in females. In contrast to Ottawa, the acute HCV cases were not as clearly younger than chronic cases. Overall, 50.0% of acute HCV cases were in persons aged 15-39 years, compared to 31.4% of chronic HCV cases in this same age group. In London, the majority (83.0%) of reported HCV cases were in persons aged 25 to 59 years, with 85.8% in males and 78.5% in females. In both sexes, acute HCV cases were significantly younger than chronic HCV cases (all p<0.01). Overall, 71.9% of acute HCV cases were persons aged 15-39 years, compared to 33.7% of chronic HCV cases in this same age group. Table 2.3 presents the annual rate per 100,000 population of reported HCV cases by age group, site and sex. Regardless of gender and site, the annual rate was higher in the 45-49, 50-54 and 55-59 year age groups. The annual rate was higher in males than in females for most age groups. For males, the highest annual rate of reported HCV cases was among persons aged 50-54 years in Hamilton, with 132.2 cases per 100,000 population. For females, the highest annual rate of reported HCV cases was among persons aged 50-54 years in London, with 47.5 cases per 100,000 population.
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Tables 2.4a, 2.4b and 2.4c present the cumulative number and proportion of reported HCV cases by risk factor, stage of HCV and sex from 2007 to 2010 for Ottawa, Hamilton and London, respectively. In Ottawa (Table 2.4a), risk factor information was available for 81.5% of the 119 acute HCV cases and 63.3% of the 872 chronic cases. Among the acute HCV cases with risk factor information, 78.4% of infections were associated with injection drug use (IDU) and 9.3% with sexual contact. Of the chronic HCV cases with risk factor information, in males, IDU accounted for 58.0% of infections, 15.7% for health care associated procedures (including blood transfusion, receipt of blood products, hemodialysis, surgery, and dental surgery), 8.7% drug snorting, 5.3% sexual contact, 3.9% other percutaneous exposures (including tattooing, body piercing, and acupuncture), and 8.4% other (including occupational exposure to blood, household contact with hepatitis C carriers, incarceration without other risk factors). In females, IDU accounted for 30.4%, health care associated procedures 23.2%, other percutaneous exposures 19.1%, drug snorting 11.3%, sexual contact 1.0%, and other 14.9%. In Hamilton (Table 2.4b), risk factor information was available for 50.0% of the 32 acute HCV cases and 29.4% of the 676 chronic HCV cases. The distribution of risk factors among the cases with risk factor information may not reflect the true distribution in Hamilton. In London (Table 2.4c), risk factor information was available for 77.2% of the 57 acute HCV cases and 99.3% of the 401 chronic cases. Of the acute HCV cases with risk factor information, 79.5% of infections was associated with injection drug use (IDU) and 9.1% drug snorting. Of the chronic HCV cases with known risk factor information, in males, IDU accounted for 71.3% of infections, drug snorting 8.9%, health care associated procedures 8.1%, other percutaneous exposures 5.3%, sexual contact 4.0%, and other 2.4%. In females, IDU accounted for 52.7%, health care associated procedures 16.0%, other percutaneous exposures 14.0%, drug snorting 8.7%, sexual contact 0.7%, and other 8.0%. Tables 2.5a, 2.5b and 2.5c present the cumulative number and proportion of reported HCV cases by region of birth, stage of HCV and sex from 2007 to 2010 for Ottawa, Hamilton and London, respectively. From the data obtained from EHSSS, region of birth information in Ottawa (Table 2.5a) was available for 82.4% of the 119 acute HCV cases and 62.4% of the 872 chronic cases. Of the acute HCV cases with known region of birth, 91.8% of infections were born in Canada. Of the chronic HCV cases with known region of birth, in males, 73.9% of infections were born in Canada, 8.5% in Asia, 7.1% in Europe and 6.8% in Africa. In females, 59.5% of infections were born in Canada, 13.7% in Africa, 12.1% in Europe, and 11.1% in Asia. In Hamilton (Table 2.5b), region of birth was available for 59.4% of the 32 acute HCV cases and 26.9% of the 676 chronic HCV cases. The distribution of region of birth among cases with
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known place of birth may not reflect the true distribution in Hamilton. However, the majority of cases were born in Canada. Region of birth information in London (Table 2.5c) was available for 77.2% of the 57 acute HCV cases and 95.5% of the 401 chronic cases. Of the acute HCV cases with known region of birth, 97.7% of infections were born in Canada. Of the chronic HCV cases with known region of birth, 88.5% of infections were born in Canada, 3.9% in Europe, and 3.4% in Asia. Tables 2.6a, 2.6b and 2.6c present the cumulative number and proportion of reported HCV cases by race/ethnicity, stage of HCV and sex from 2007 to 2010 for Ottawa, Hamilton and London, respectively. In the data from EHSSS (Table 2.6a), race/ethnicity information in Ottawa was available for 82.4% of the 119 acute HCV cases and 62.8% of the 872 chronic cases. Of the acute HCV cases with known race/ethnicity, 80.6% of infections were Caucasian, 9.2% Aboriginal, 2.0% Black, 2.0% Asian and 6.1% other. Of the chronic HCV cases with known race/ethnicity, 73.9% of infections were Caucasian, 9.1% Black, 8.2% Asian, 4.6% Aboriginal and 4.2% other. In Hamilton (Table 2.6b), region of birth was available for 56.3% of the 32 acute HCV cases and 25.7% of the 676 chronic HCV cases. The distribution of race/ethnicity among cases with known may not reflect the true distribution in Hamilton; however, the majority of cases were Caucasian. Race/ethnicity information in London (Table 2.6c) was available for 77.2% of the 57 acute HCV cases and 98.8% of the 401 chronic HCV cases. Of the acute HCV cases with known race/ethnicity, 90.9% of infections were Caucasian, and 9.1% Aboriginal. Of the chronic HCV cases with known race/ethnicity, 84.3% of infections were Caucasian, 6.1% Aboriginal, 4.3% Asian, 2.3% Black, and 3.0% other. 3.3 Modeled HCV prevalence and incidence in Ontario, 2007 Tables 3.1a and 3.1b present the estimated prevalence of HCV infections by place of birth, sex and exposure category. Overall, among 12,885,750 persons living in Ontario as of December 2007, an estimated 109,717 were infected with hepatitis C, for a prevalence rate of 0.85% or about one in 117 persons. Persons born in Canada accounted for 79,051 (72%) of these infections compared to 30,667 among immigrants. The prevalence rate in persons born in Canada was slightly higher than that among immigrants (0.86% compared to 0.83%). 60% of prevalent HCV infections were among males, who had a prevalence rate 1.5-fold higher than that of females. Not surprisingly, the majority of prevalent HCV infections were among injection drug users. Current and ex-IDUs accounted for 54% of the HCV-infected persons in Ontario. Persons who
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were infected through receipt of a blood transfusion accounted for 11% of HCV infections, hemophilia patients less than 1% and persons infected by other routes of transmission, 35%. In the model, 2,414 HCV-infected persons were also infected with HIV. IDUs accounted for 96% of the HCV-HIV co-infected persons. Note that this estimate does not include all persons with HCV-HIV coinfection in Ontario. Table 3.2 presents the estimated number of incident HCV infections by place of birth, sex and exposure category in calendar year 2007. Overall, 3,470 persons in Ontario were newly infected with HCV in 2007, for an overall incidence rate of 0.027% or about one in 3,680 persons. 2,250 (65%) of new HCV infections occurred in men, who had an incidence rate almost double that of women (0.036% compared to 0.019%). As expected, 80% of new HCV infections occurred in active injection drug users. Table 3.3 shows the modeled HCV prevalence number and rate by health region and public health unit in 2007. HCV prevalence varied substantially by public health unit but not by health region. Nevertheless, HCV prevalence was highest in the Eastern other and Toronto health regions with 1.36% and 1.07%, respectively, and lowest in the Central East other region at 0.70%. HCV prevalence varied considerably by public health unit, from a low of 0.27% in Huron to a high of 3.47% in Kingston. The rate in Kingston was 2.4 times higher than the next highest public health unit. In eight public health units, the HCV prevalence rate was 1.0% or greater and in four public health units, it was less than 0.50%. HCV prevalence was 0.50% to 0.99% in the remaining 24 public health units. Table 3.4 presents the modeled incidence of sequelae of HCV infection in Ontario from 1967 to 2027. In 2007, 359 persons developed cirrhosis, 216 persons progressed to decompensated liver failure, 135 cases were diagnosed with hepatocellular carcinoma and 61 persons received a liver transplant due to their HCV infection. In all, 223 persons died of HCV-related causes in 2007. According to our model, the incidence of cirrhosis increased from 1967 to 1997, was relatively stable at around 360 new cases annually from 1997 to 2012 and will decrease slightly in subsequent years. However, the incidence of the more advanced sequelae and mortality due to HCV will continue to increase over the entire study period. The number of deaths from all HCV-related causes is projected to increase from 223 in 2007 to 291 in 2027, an increase of 31%. Table 3.5 presents the modeled prevalence of sequelae of HCV infection in Ontario from 1967 to 2027. This table presents the total number of persons living with each complication of HCV infection; thus, the estimates are not mutually exclusive. In 2007, an estimated 7,330 persons were living with cirrhosis, 2,525 in decompensated liver failure, 157 persons diagnosed with hepatocellular carcinoma and 549 post-transplant patients. According to our model, the prevalence of the sequelae of HCV infection will continue to increase in future. The most dramatic increase is projected among post-transplant patients, from 549 in 2007 to 914 in 2027, an increase of 66%.
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4. DISCUSSION Hepatitis C became a reportable disease in Ontario in October 1991. Overall, 97,392 HCV infections were reported to the Ontario reportable disease surveillance system from 1992 to 2010. In the most recent six years from 2005 to 2010, about 4,500 new HCV cases were reported annually of whom 62% were male. The annual rate of reported HCV cases was 32-36 per 100, 000 population, much higher among males (40-48 per 100,000) than females (23-29 per 100,000). According to data from EHSSS from 2007 to 2010, the total number of reported HCV cases was 1,031 in Ottawa, 715 in Hamilton, and 419 in London. For acute HCV infections alone, it was 119 in Ottawa, 32 in Hamilton, and 57 in London. IDU was the predominant risk factor for HCV infection in all three sites. During this period, 25% of HCV infections in Ottawa and 15% in London were from minority population groups. Statistical modeling revealed that, as of December 2007, 109,717 persons in Ontario were infected with hepatitis C, and 3,470 new infections occurred in 2007. HCV incidence among men overall was 0.036%, almost twice that among females with 0.019%. Of the almost 110,000 HCV-infected persons in Ontario, 21,632 (20%) were active IDUs and 37,253 (34%) past IDUs, 12,025 (11%) had been infected through blood transfusion, 372 (0.34%) were hemophilia patients and 38,436 (35%) were infected through other modes of transmission, including sexual, occupational, nosocomial and vertical transmission. HCV prevalence varied considerably by public health unit but to a lesser degree by health region. The largest number of HCV-infected persons (27,888, or 25%) were resident in Toronto, with the next highest being Ottawa, with 7,380 prevalent HCV infections. However, the rate varied substantially by public health unit, from a high of 3.47% in Kingston to a low of 0.27% at the Huron County Public Health Unit. The impact of the sequelae of hepatitis C infection on the health of persons in Ontario appears to be considerable. In 2007, 7,330 persons were living with cirrhosis, 2,525 were in liver failure, 157 had been diagnosed with hepatocellular carcinoma and 549 were post-transplant patients. The annual incidence of new cases of cirrhosis appeared to plateau in 1997 but, according to the results of our model, the incidence of the more serious outcomes of HCV infection will continue to rise, at least until 2027. Liver deaths, for example, increased from only 12 in 1967 to 291 in 2027, increasing approximately 30% from 2007 to 2027. Due to limitations in our data and analytic methods, the results in the present report should be interpreted with caution. Data on reported cases of HCV in Ontario do not distinguish acute from chronic infections, risk factor information was not systematically collected, and it is unclear whether a significant number of duplicate cases remain in the data. EHSSS data provides more detailed and reliable risk factor information and attempts to differentiate between acute and chronic infections. However, currently, only some cities in Ontario have been participating in the surveillance system, which comprised fewer than 20% of reported HCV cases in Ontario
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from 2005 to 2010. Toronto has been recently added to the network and this should provide important new data over the coming years. The modeled HCV estimates are hypotheses, not conclusions, based on several assumptions. The explanation of these assumptions and limitations of the modeling methods have been described in detail in the previous report <4>. With regard to demographic characteristics, data on births, deaths and census populations were relatively precise and therefore not subject to significant uncertainty. Immigration figures were derived from the Canadian model multiplied by the proportion of Canadian immigrants who settled in Ontario. This is also relatively reliable. However, to determine the prevalence of HCV infection in immigrants, the research team relied on HCV in the country of origin as reflected by the occurrence of HCV among persons not born in Canada in the EHSSS database. It is unclear how precise the country birth data is in this database. The model developed by Remis incorporates assumptions about the likely incidence and prevalence of HCV in key populations. The results of the model are based on data derived from epidemiologic studies and from the EHSSS surveillance project implemented by the Public Health Agency of Canada. However, no population-based data on HCV prevalence or incidence is available in Ontario. It is hoped that population-based surveys will be carried out in the near future to provide empirical estimates of HCV prevalence. The EHSSS also has limitations related to incomplete and biased data. These are discussed more fully in the report of HCV in Canada in 2002 <3>. Risk factor data were not systematically available from reported cases, which would have helped to assess indirectly the relative infection rates in the principal groups at risk for HCV.
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References 1. Choo QL, Kuo G, Wiener AJ, et al. Isolation of a cDNA clone derived from a blood-borne
non-A, non-B viral hepatitis genome. Science, 1989, 244:359-362 2. Cranston, L. Building a better blood system for Canadians. Canadian Journal of Public
Health, 2000, 91(Supplement):S40-41. 3. Remis RS, Palmer RWH, Hershfield NC. A study to characterize the epidemiology of
hepatitis C infection in Canada, 2002. September 2003 [Technical report for Hepatitis C Division, Centre for Infectious Disease Prevention and Control, Health Canada].
4. Remis R. The Epidemiology of Hepatitis C Infection in Ontario, 2004. Final Report.
Toronto: Hepatitis C Secretariat, Community Health Division, Ontario Ministry Of Health and Long Term Care; 2006
5. Remis R. The Epidemiology of Hepatitis C Infection in Ontario, update to 2007. Final
Report. Toronto: Hepatitis C Secretariat, Community Health Division, Ontario Ministry of Health and Long Term Care; 2008
6. Ontario Public Health Standards 2008. Accessed at: http://www.health.gov.on.ca/english/providers/program/pubhealth/oph_standards/ophs/progstds/pdfs/ophs_2008.pdf
7. Zou S, Zhang J, Tepper M, et al. Enhanced surveillance of acute hepatitis B and C in four
health regions in Canada, 1998 to 1999. Canadian Journal of Infectious Diseases, 2001, 12: 357-63.
8. Wu HX, Wu J, Wong T, et al. Enhanced surveillance of newly acquired hepatitis C virus
infection in Canada, 1998-2004. Scandinavian Journal of Infectious Disease, 2006, 38:482-89.
Public Health Division, Ontario Ministry of Health and Long-Term Care (2000-2010) Population estimates provided by Statistics Canada. Table 510001 - Estimates of population, by age group and sex for July 1, Canada, provinces and territories, annually
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Table 1.2 Reported cases and rate1 of hepatitis C by year and sex Ontario, 2005-2010
Year Number of cases Rate1
Male Female Total Male Female Total 2005 2,944 1,623 4,567 47.6 25.6 36.5 2006 2,554 1,447 4,001 40.8 22.6 31.6 2007 2,769 1,820 4,589 43.9 28.1 35.9 2008 2,816 1,887 4,703 44.2 28.8 36.4 2009 2,802 1,769 4,571 43.5 26.7 35.0 2010 2,736 1,645 4,381 42.0 24.6 33.2 1. Rate per 100,000 population Sources: Ontario Ministry of Health and Long-Term Care, integrated Public Health Information System (iPHIS) database,
extracted [2011/03/21] for 2005-2009 and [2011/02/14] for 2010 Population estimates provided by Statistics Canada. Table 510001 - Estimates of population, by age group and sex for July 1, Canada, provinces and territories, annually
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Table 1.3a Number and proportion1 of reported cases and rate2 of hepatitis C by age and sex, Ontario, 2005
[2011/03/21] for 2005-2009 and [2011/02/14] for 2010 2005 population estimates provided by Statistics Canada. Table 510001 - Estimates of population, by age group and sex for July 1, Canada, provinces and territories, annually
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Table 1.3b Number and proportion1 of reported cases and rate2 of hepatitis C by age and sex, Ontario, 2006
[2011/03/21] for 2005-2009 and [2011/02/14] for 2010 2006 population estimates provided by Statistics Canada. Table 510001 - Estimates of population, by age group and sex for July 1, Canada, provinces and territories, annually
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Table 1.3c Number and proportion1 of reported cases and rate2 of hepatitis C by age and sex, Ontario, 2007
[2011/03/21] for 2005-2009 and [2011/02/14] for 2010 2007 population estimates provided by Statistics Canada. Table 510001 - Estimates of population, by age group and sex for July 1, Canada, provinces and territories, annually
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Table 1.3d Number and proportion1 of reported cases and rate2 of hepatitis C by age and sex, Ontario, 2008
[2011/03/21] for 2005-2009 and [2011/02/14] for 2010 2008 population estimates provided by Statistics Canada. Table 510001 - Estimates of population, by age group and sex for July 1, Canada, provinces and territories, annually
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Table 1.3e Number and proportion1 of reported cases and rate2 of hepatitis C by age and sex, Ontario, 2009
[2011/03/21] for 2005-2009 and [2011/02/14] for 2010 2009 population estimates provided by Statistics Canada. Table 510001 - Estimates of population, by age group and sex for July 1, Canada, provinces and territories, annually
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Table 1.3f Number and proportion1 of reported cases and rate2 of hepatitis C by age and sex, Ontario, 2010
[2011/03/21] for 2005-2009 and [2011/02/14] for 2010 2010 population estimates provided by Statistics Canada. Table 510001 - Estimates of population, by age group and sex for July 1, Canada, provinces and territories, annually
[2011/03/21] for 2005-2009 and [2011/02/14] for 2010 2005 population estimates provided by Statistics Canada. Table 109-5325 Estimates of population (2006 Census and administrative data), by age group and sex, Canada, provinces, territories, health regions (2007 boundaries) and peer groups, annually (Number) 1996 to 2010
[2011/03/21] for 2005-2009 and [2011/02/14] for 2010 2006 population estimates provided by Statistics Canada. Table 109-5325 Estimates of population (2006 Census and administrative data), by age group and sex, Canada, provinces, territories, health regions (2007 boundaries) and peer groups, annually (Number) 1996 to 2010
[2011/03/21] for 2005-2009 and [2011/02/14] for 2010 2007 population estimates provided by Statistics Canada. Table 109-5325 Estimates of population (2006 Census and administrative data), by age group and sex, Canada, provinces, territories, health regions (2007 boundaries) and peer groups, annually (Number) 1996 to 2010
[2011/03/21] for 2005-2009 and [2011/02/14] for 2010 2008 population estimates provided by Statistics Canada. Table 109-5325 Estimates of population (2006 Census and administrative data), by age group and sex, Canada, provinces, territories, health regions (2007 boundaries) and peer groups, annually (Number) 1996 to 2010
[2011/03/21] for 2005-2009 and [2011/02/14] for 2010 2009 population estimates provided by Statistics Canada. Table 109-5325 Estimates of population (2006 Census and administrative data), by age group and sex, Canada, provinces, territories, health regions (2007 boundaries) and peer groups, annually (Number) 1996 to 2010
[2011/03/21] for 2005-2009 and [2011/02/14] for 2010 2010 population estimates provided by Statistics Canada. Table 109-5325 Estimates of population (2006 Census and administrative data), by age group and sex, Canada, provinces, territories, health regions (2007 boundaries) and peer groups, annually (Number) 1996 to 2010
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Table 1.5 Number and proportion of reported hepatitis C case by year, exposure category and sex Ontario 2007-2009
Exposure Category Male Female Unk/other/
transgender Total
Number %1 %2 Number %1 %2 Number %1 %2 2007 IDU 1,007 37.2% 69.8% 487 27.4% 54.8% 12 1,506 33.4% 64.2% Blood transfusion3 133 4.9% 9.2% 185 10.4% 20.8% 0 318 7.0% 13.6% MTC4 23 0.85% 1.6% 11 0.62% 1.2% 0 34 0.75% 1.4% High risk sexual contact5 23 0.85% 1.6% 45 2.5% 5.1% 0 68 1.5% 2.9% Miscellaneous6 20 0.74% 1.4% 21 1.2% 2.4% 0 41 0.91% 1.7% Other7 237 8.8% 16.4% 140 7.9% 15.7% 1 378 8.4% 16.1% Unknown 1,265 46.7% 891 50.1% 11 2,167 48.0% Total 2,708 100% 100% 1,780 100% 100% 24 4,512 100% 100% 2008 IDU 1,095 39.1% 62.0% 548 29.3% 47.7% 13 1,656 35.3% 56.5% Blood transfusion 163 5.8% 9.2% 209 11.2% 18.2% 0 372 7.9% 12.7% MTC 12 0.43% 0.68% 10 0.54% 0.87% 0 22 0.47% 0.75% High risk sexual contact 26 0.93% 1.5% 33 1.8% 2.9% 0 59 1.3% 2.0% Miscellaneous 36 1.3% 2.0% 30 1.6% 2.6% 0 66 1.4% 2.3% Other 434 15.5% 24.6% 318 17.0% 27.7% 3 755 16.1% 25.8% Unknown 1,037 37.0% 720 38.5% 8 1,765 37.6% Total 2,803 100% 100% 1,868 100% 100% 24 4,695 100% 100% 2009 IDU 1,094 39.0% 63.7% 558 31.5% 49.5% 7 1,659 36.2% 58.1% Blood transfusion 137 4.9% 8.0% 187 10.6% 16.6% 0 324 7.1% 11.3% MTC 12 0.43% 0.70% 12 0.68% 1.1% 0 24 0.52% 0.84% High risk sexual contact 31 1.1% 1.8% 43 2.4% 3.8% 0 74 1.6% 2.6% Miscellaneous 29 1.0% 1.7% 28 1.6% 2.5% 0 57 1.2% 2.0% Other 414 14.8% 24.1% 300 17.0% 26.6% 3 717 15.6% 25.1% Unknown 1,085 38.7% 641 36.2% 5 1,731 37.7% Total 2,802 100% 100% 1,769 100% 100% 15 4,586 100% 100% 1. Column percent with unknown 2. Column percent with known risk factor 3. Includes blood transfusion pre-1989/unknown date/outside Canada, received blood or blood products 4. Includes cases with MTC risk factor selected, or those <1 year of age 5. Includes partner/spouse was HCV+, sex trade worker or sex with sex trade worker, MSM 6. Includes occupational exposure, born in an endemic country, inhalation drug use, organ/tissue transplant, dialysis 7. All other risks - other sexual (e.g. multiple partners), fighting/biting, homeless, tattoo/piercing/acupuncture/electrolysis, lived/travelled to endemic country, immunocompromised, invasive procedure (medical/dental/surgical), shared personal items (e.g. razors), other/household contact (non-sexual) Source: Ontario Ministry of Health and Long-Term Care, integrated Public Health Information System (iPHIS)
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Table 1.6 Number and proportion of reported hepatitis C case by year, exposure category and health region Ontario 2007-2009
Exposure Category Toronto Ottawa Northern Eastern, other Central East, other Central West Southwest
Number %1 Number %1 Number %1 Number %1 Number %1 Number %1 Number %1 2007 IDU 250 56.7% 136 73.1% 155 80.7% 226 75.1% 218 47.6% 307 66.9% 202 68.5% Blood transfusion2 57 12.9% 19 10.2% 16 8.3% 22 7.3% 101 22.1% 71 15.5% 32 10.8% MTC3 7 1.6% 2 1.1% 3 1.6% 4 1.3% 13 2.8% 5 1.1% - 0.0% High risk sexual contact4 30 6.8% 2 1.1% 1 0.52% 6 2.0% 10 2.2% 8 1.7% 11 3.7% Miscellaneous5 9 2.0% 5 2.7% 1 0.52% 1 0.33% 13 2.8% 8 1.7% 4 1.4% Other6 88 20.0% 22 11.8% 16 8.3% 42 14.0% 103 22.5% 60 13.1% 46 15.6% Unknown 610 49 193 120 634 364 186 Total 1,051 100% 235 100% 385 100% 421 100% 1,092 100% 823 100% 481 100% 2008 IDU 291 46.5% 147 61.5% 207 83.5% 163 65.7% 243 37.1% 309 61.4% 283 71.6% Blood transfusion 102 16.3% 31 13.0% 16 6.5% 22 8.9% 116 17.7% 47 9.3% 38 9.6% MTC 8 1.3% - 0.0% - 0.0% 1 0.40% 7 1.1% 5 0.99% 1 0.25% High risk sexual contact 5 0.80% 2 0.84% 4 1.6% 10 4.0% 17 2.6% 12 2.4% 9 2.3% Miscellaneous 10 1.6% 6 2.5% 2 0.81% 2 0.81% 18 2.7% 23 4.6% 5 1.3% Other 210 33.5% 53 22.2% 19 7.7% 50 20.2% 254 38.8% 107 21.3% 59 14.9% Unknown 440 31 163 118 470 326 209 Total 1,066 100% 270 100% 411 100% 366 100% 1,125 100% 829 100% 604 100% 2009 IDU 276 49.8% 163 59.9% 205 78.8% 199 74.3% 251 38.1% 288 62.3% 270 72.8% Blood transfusion 85 15.3% 33 12.1% 27 10.4% 19 7.1% 96 14.6% 37 8.0% 27 7.3% MTC 9 1.6% - 0.0% 1 0.38% - 0.0% 9 1.4% 4 0.87% 1 0.27% High risk sexual contact 23 4.2% 1 0.37% 5 1.9% 4 1.5% 15 2.3% 12 2.6% 14 3.8% Miscellaneous 6 1.1% 3 1.1% 2 0.77% 4 1.5% 17 2.6% 16 3.5% 9 2.4% Other 155 28.0% 72 26.5% 20 7.7% 42 15.7% 270 41.0% 105 22.7% 50 13.5% Unknown 404 32 155 108 453 334 240 Total 958 100% 304 100% 415 100% 376 100% 1,111 100% 796 100% 611 100% 1. Column percent with known risk factor 2. Includes blood transfusion pre-1989/unknown date/outside Canada, received blood or blood products 3. Includes cases with MTC risk factor selected, or those <1 year of age 4. Includes partner/spouse was HCV+, sex trade worker or sex with sex trade worker, MSM 5. Includes occupational exposure, born in an endemic country, inhalation drug use, organ/tissue transplant, dialysis 6. All other risks - other sexual (e.g. multiple partners), fighting/biting, homeless, tattoo/piercing/acupuncture/electrolysis, lived/travelled to endemic country, immunocompromised, invasive procedure (medical/dental/surgical), shared personal items (e.g. razors), other/household contact (non-sexual) Source: Ontario Ministry of Health and Long-Term Care, integrated Public Health Information System (iPHIS)
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Table 2.1 Number and annual rate (per 100,000 population) of reported HCV cases by site, year of diagnosis, stage of HCV and sex, EHSSS, Ontario, 2007 to 2010
Number of reported HCV Annual rate (per 100,000) Acute Chronic Indeterminate Total Total Males Females Total Males Females Total1 Males Females Total Males Females Total Males Females Total Ottawa 2007 12 13 25 130 65 195 8 5 13 150 83 233 35.8 19.0 27.2 2008 8 22 30 143 86 229 5 6 11 156 114 270 36.7 25.7 31.1 2009 19 18 37 155 100 256 4 4 8 178 122 301 41.3 27.1 34.2 2010 17 10 27 133 59 192 4 4 8 154 73 227 35.1 16.0 25.3 Hamilton 2007 3 4 7 109 53 162 0 1 1 112 58 170 43.3 21.8 32.4 2008 5 1 6 100 57 157 2 1 3 107 59 166 41.2 22.0 31.5 2009 3 1 4 107 68 175 1 1 2 111 70 181 42.5 26.0 34.1 2010 9 6 15 125 57 182 1 0 1 135 63 198 51.5 23.2 37.1 London 2007 6 3 9 59 41 100 2 4 6 67 48 115 30.7 21.2 25.9 2008 12 10 22 52 42 95 6 6 12 70 58 129 31.8 25.4 28.8 2009 6 8 14 87 41 128 4 5 9 97 54 151 43.8 23.5 33.4 2010 8 4 12 51 27 78 5 1 6 64 32 96 28.7 13.8 21.1 1. Includes one chronic HCV case with unknown sex in Ottawa in 2009, one in London in 2008 Sources: Enhanced Hepatitis Strain Surveillance System, Public Health Agency of Canada 2007 to 2010 population estimates for each public health unit provided by Statistics Canada
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Table 2.2a Cumulative number and proportion of reported HCV cases by age group, stage of HCV and sex EHSSS, Ottawa, 2007 to 2010