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Canada Communicable Disease Report

Canada Communicable Disease Report

1 October 2007

Volume 33

Number 11

A provincial and territorial review of hepatitis A in men who have sex with men

S Uhlmann, MSc, PPH (1), JA Buxton, MBBS, MHSc (1) (2)

  1. Epidemiology Services, BC Centre for Disease Control, Vancouver, BC

  2. Department Health Care and Epidemiology, Vancouver, University of British Columbia, BC

Introduction

Hepatitis A virus (HAV) outbreaks among men who have sex with men (MSM) have been reported in urban areas of Canada, the United States (US), Europe and Australia(1-6). HAV usually causes clinical infection in adults with liver inflammation resulting in anorexia, nausea, fatigue, fever, and jaundice, and rarely in extreme cases, liver necrosis and death. HAV is transmitted by the fecal-oral route, through direct person-to-person contact or by ingestion of contaminated water or foods(7). There is no specific treatment for HAV infection, however vaccines are known to be effective in preventing infection(8).

The National Advisory Committee on Immunization (NACI) in Canada and the Advisory Committee on Immunization Practices (ACIP) in the US recommend hepatitis A immunization for specific groups at high risk of infection including MSM(1,7). Despite these recommendations, provinces and territories (P/T's) differ with respect to MSM in terms of prevention strategies, immunization policies and data gathering. There is little published information in Canada regarding risk factors for MSM, MSM population estimates, or number of HAV cases where MSM is identified as the primary risk factor.

The aim of this study is to review what is known about HAV infection in MSM in Canada. We will summarize current P/T practices regarding pre-exposure immunization recommendations and identification of MSM as a risk factor for HAV; and describe reported outbreaks. This information will identify knowledge gaps and help with HAV prevention in Canada.

Methods

Medline (1966-2007, February) was searched for relevant publications. MeSH terms included: hepatitis A, men, gay, homosexual, sex, vaccination, seroprevalence and Canada. All Canadian P/T's were surveyed via email questionnaire (British Columbia [BC] was not surveyed as it was the site of research and relevant material was available). Questions included HAV prevention strategies in the MSM population, vaccine coverage, number of cases identified as MSM, MSM population size and seroprevalence estimates. Public health professional(s) responsible for immunization and/or communicable disease in each P/T completed the surveys. Authors of studies/reports, which described outbreaks and estimated MSM population size, were also contacted.

Results

Of the 12 surveys sent out, nine P/T's responded. One responding province was unable to access paper records as they were converting to electronic records.

P/T's differ with respect to HAV surveillance and pre-exposure vaccine recommendations for MSM populations (Table 1). The cost of HAV vaccine for pre-exposure prophylaxis for MSM is provincially funded in eight of 13 P/T's(9). Monovalent hepatitis A vaccines are used in most responding P/T's. Combination hepatitis A and B vaccine may be recommended if the person is not protected against hepatitis B infection, especially in Quebec (QC). Seroprevalence rates were reported in BC and QC (Table 1). Northwest Territories reported no HAV cases in MSM in the years studied, Yukon Territory reported no cases in the past 5 years and QC reported between zero and seven cases a year from 2000 to 2004.

Table 1. Provincial/territorial summary of hepatitis A in men who have sex with men (MSM)

Province Pre-exposure HAV vaccine recommended and funded Year funded MSM targeted through education or media MSM population size* HAV seroprevalence among MSM Reported outbreaks in MSM
British Columbia Yes 2001 Media campaigns, posters and letters to physicians Vancouver: 20,000 (1998)
BC: 33,300-75,800 (2004)		 Vancouver: 28% (1998) 1990-1991, 1997
Alberta Yes 2004 – – – No
Saskatchewan No N/A No – – No
Manitoba Yes 2000 – – – No
Ontario Yes 2003 Local health units – – 1991
1996
Quebec Yes 1997 Publicly funded local clinics Montreal: 35,000-40,000 (2001) < 30 yr = 8%
30-34 yr =17%
35-39 yr = 27%
≥ 40 yr = 46%
Total = 26% (1997)		 1990-1992, 1994-1997
New Brunswick No N/A – – – –
Nova Scotia No N/A – – – –
Prince Edward Island Yes† – – – – –
Newfoundland and Labrador Yes 1995 – – – –
Yukon Yes 1995 Through education and one-to-one counselling – – No
Northwest Territories Yes 1994 Advertisements through local networks and STI clinic – – No
Nunavut No N/A – – – –
* 2003 Census, 1.8% Canadian males † Unknown whether vaccine funded. – Unknown or no response; N/A not applicable

Outbreaks

Reported HAV outbreaks in MSM occurred in Vancouver (1990-1991, 1997), Toronto (1991, 1996) and Montréal (1990-1992, 1994-1997).

Vancouver

During the 1990 HAV outbreak, the male to female ratio of serologically confirmed cases of HAV was approximately 4:1 (108 males: 26 females). Twice as many of the males, whose sexual orientation was reported by the attending physicians, were homosexual compared to heterosexual(4). During the 1997 outbreak, the number of HAV cases reported in Vancouver at the end of the year increased by 100% compared to the previous few months. More than 90% of the cases were male, and of these > 50% were MSM. In response to the outbreak, Vancouver Coastal Health introduced an HAV immunization campaign for MSM. Public awareness was achieved through press releases, media stories and advertisements in community papers, pamphlets, fliers, and posters. Over 6,000 MSM were immunized. Almost 60% of respondents of a survey evaluating the campaign reported being immunized. However, surveys were administered at sites similar to where outreach immunization had occurred (e.g., gay bars and clubs). The MSM population in Vancouver at that time was estimated to be about 20,000.

Toronto

Two MSM outbreaks have been reported in the literature for Toronto(2,10). However Toronto Public Health could not confirm either outbreak due to a lack of available information in the provincial data collection system. According to the publications, Toronto experienced an HAV outbreak in MSM, from January to September 1991. During this time, 274 cases of HAV were reported, 234 (85%) of which were males aged 20 to 49 years. Risk factor information was collected for 169 male cases and 94 (56%) identified homosexual behaviour. The second reported HAV outbreak in Toronto occurred in MSM in 1996. Of the 68 cases identified as being sexually transmitted, 64 (94%) were male. A survey of MSM following the outbreak showed that almost nine out of 10 respondents were aware of the outbreak and that many of them were practicing safer sex. The awareness campaign consisted of an advertisement in a gay newspaper and a poster produced by the Department of Public Health. Since this peak in 1996, HAV cases identified as MSM have steadily decreased.

Montréal

Between 1990 and 1992 an HAV epidemic in the Montréal region affected gay men living in the downtown area. The incidence rate rose to almost 70 cases per 100 000 person-years in men, compared to < 10 per 100 000 person-years in women. A second outbreak in MSM occurred in 1994 and lasted until 1997. Between 1 November, 1994 and 31 December, 1995, 261 cases of HAV were reported to Direction de la santé publique de la région de Montréal-Centre. The incidence rate was 200% higher than the preceding 4 months; 78.5% of cases were male and were concentrated in the Montreal downtown area. Cases where MSM was identified as the main risk factor increased significantly in 1995 whereas other risk factors (such as travel to HAV endemic countries) remained stable. Eighteen percent of MSM cases were food handlers(11). In response to the outbreak a working group was formed in January 1995 to monitor the situation and develop intervention strategies. A news release was sent to gay newspapers, and pamphlets were distributed in gay bars and movie theatres.

Education

P/T's identified several ways that MSM are targeted for HAV awareness and education. Methods include advertisements in general and MSM-specific media outlets, posters, letters to physicians, one-to-one counselling, and awareness and vaccination campaigns in local health units, clinics and bars in response to outbreaks.

Seroprevalence

Several Canadian studies have examined HAV seroprevalence in MSM to determine whether MSM are indeed at higher risk(3, 12-14). Ochnio et al. (1998) found that in Vancouver, anti-HAV prevalence was significantly higher among MSM, than among Vancouver travellers (28% vs. 20.5%, p = 0.015) matched by age and place of birth, but whose sexual preferences were unknown(13). In another study among Vancouver street youth, MSM were at higher risk for past HAV infection, although this association was not significant (p = 0.07)(14). A Montréal study found 26% of MSM were seropositive, although these results were not compared to heterosexual men(3). A seroprevalence study of Montréal street youth showed insertive anal penetration to be a risk factor for HAV infection (adjusted odds ratio: 5.1; 95% confidence interval: 1.6 to 16.7), although this was not specific to MSM(12).

MSM population estimates

Using model-derived scenarios, Hogg et al. estimated the above 19-year-old MSM population in Vancouver to be between 5,406 and 16,219, from 1987 to 1992(15). In 2004, Gilbert estimated the BC gay male population to range from 33,300 to 75,800 by multiplying the percent of gay males in a region (found from six different studies), by census data (Gilbert, 2004. Who is a Gay Man? Unpublished report). Quebec reported the MSM population to be approximately 5% of the male population and in 2001, the MSM population of Montreal was estimated to be between 35,000 and 40,000(3). Other P/T's did not report population estimates.

Discussion

We found that despite Canadian immunization guide recommendations, surveillance and pre-exposure HAV immunization in MSM is not nationally standardized. Because of the difference in manner of reporting cases and rates by each jurisdiction and in the literature it is difficult to compare between P/Ts. Further, there is a paucity of data assessing the burden of HAV illness in MSM in Canada. Many P/T's do not routinely collect risk factor information specifically for MSM, so most responding P/T's were unable to identify persons with HAV infections who were MSM. Population estimates of MSM, vaccine coverage and HAV trends in MSM were generally unavailable, which adds to the challenges of studying an open, dynamic population.

Whether MSM are actually at greater risk of HAV infection is not well understood. Seroprevalence studies from Vancouver suggest a greater risk, however other studies report conflicting results(12,16-20). Studies have found HAV infection in MSM to be associated with different risk factors, such as, increasing age(19-21); number of lifetime sexual partners(1,20-24); past infection with a sexually transmitted infection (STI)(17,21), visits to gay saunas(19,24,25); group sex(22,24); insertive-anal, oral-anal and digital-rectal intercourse(1,22-24); sharing needles without cleaning(23) and ethnicity (Latino)(23). The differences observed in HAV risk and risk factors may represent differences in the communities being studied, such as differing sexual practices or lifestyles, MSM population size and concentration, and mobility. Vancouver and Montréal have geographically concentrated gay populations, which may facilitate the spread, awareness and identification of HAV infection in these populations. HAV cases in larger urban areas or rural areas with more diffuse MSM populations may not be identified as MSM.

Toronto, Montréal and Vancouver all experienced outbreaks in the early 1990's and again in the mid-to-late 1990's. The temporal clustering suggests that HAV may have spread from one MSM community to another. This underscores the need to control HAV in MSM, as localized outbreaks may affect other P/T's. Outbreaks in MSM may also have wider implications in the general public as a significant number of MSM may be food handlers(11). A proportion of the HAV cases identified in males could be due to an increased awareness. However this would not account for such a large difference between the reported incidence of HAV in males and females.

Despite the data limitations, it appears that MSM cases made up only a small proportion of overall HAV cases in the past few years. For example, in Vancouver HAV cases in MSM dropped from 77 cases in 1999 to no reported cases in 2004, while travel related cases remained relatively constant in the same time period(26). This decrease coincides with the availability of publicly funded vaccine for all MSM in BC. Although this shows the success of a public health response, it should be remembered that HAV infection and outbreaks have a cyclic nature.

Using standardized follow-up forms containing sensitive personal/sexual preference questions, may make it easier for public health nurses or public health inspectors to gather sexual practice information. This would help identify the source of an infection, risk factors, and outbreaks in MSM to allow interventions in a timely manner.

HAV immunization coverage in MSM has been assessed during outbreaks through surveys of self-reported vaccine uptake in convenience samples. However it is difficult to assess total MSM population coverage without accurate estimations of MSM populations and immunization registries, which include reason for vaccine administration. The 2003 Canadian Census included a question on sexual orientation and found that 1.8% of Canadian men self-reported as gay or bisexual. Available provincial estimates are few and must be interpreted with caution due to high sampling variability. The reason for HAV immunization and hence the number of MSM immunized in each health region may not be recorded; therefore the effectiveness of immunization campaigns and whether HAV-specific public health initiatives are meeting their goals cannot be assessed.

There are several limitations to a study of this nature. In Canada, approximately one in 7.6 cases of HAV are actually reported, thus the number of cases and/or rates attributed to any population will be an underestimate(27). As well, since MSM risk factor information is not routinely collected, a province that reported zero MSM cases for a given year may have had cases that went unreported.

Conclusion

MSM no longer make up a significant proportion of HAV cases in the P/T's where this risk factor information is collected. This decline may be the result of targeted immunization campaigns and pre-exposure immunization policies, or in part follow the natural cycle of the disease. The systematic collection of MSM risk factor information would help assess whether this burden is indeed small in all P/T's and enable early identification of future outbreaks in MSM populations to allow timely public health interventions.

Acknowledgements

The authors would like to thank L. McDonald (Alberta Health and Wellness, Alberta), H. Bangura (Saskatchewan Health, Saskatchewan), M. Long (Manitoba Health, Winnipeg, Manitoba), L. Schiedel (Ontario Ministry of Health and Long-Term Care, Toronto, Ontario), V. Gilica (Quebec Health and Social Services), L. Cochrane (New Brunswick Health and Wellness), Dr. A. Al-Azem (Nova Scotia Department of Health, Halifax, Nova Scotia), C. Hemsley (Yukon Department of Health and Social Services), W. White (Health and Social Services, Yellowknife, Northwest Territories), R. Hogg (Simon Fraser University, Vancouver, British Columbia), Dr. M. Gilbert (BC Centre for Disease Control, Vancouver, British Columbia), Dr. R. Shahin (Toronto Public Heath, Toronto, Ontario), Dr. J. Ochnio (University of British Columbia, Vancouver, British Columbia), S. Krilow (BC Centre for Disease Control, Vancouver, British Columbia), Dr. T. Tannenbaum (Montreal Public Health Department, Montreal, Quebec).

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