Seroprevalence and Risk Factors for Hepatitis A among Montreal Street Youth

Article excerpt

ABSTRACT

Objective: To estimate the prevalence of hepatitis A virus (HAS antibodies among Montreal street youth.

Method: Anti-HAV antibody testing was performed on blood samples from a hepatitis B and C study conducted among street youth in 1995-96.

Results: Among the 427 youth aged 14 to 25 years, prevalence of HAV antibodies was 4.7% (95% confidence interval [CI]: 2.9%-7.2%). A multivariate logistic regression analysis showed that birth in a country with a high anti-HAV prevalence (Adjusted odds ratio [AOR]: 200.7; 95% CI: 38.1-1058.4), having had sexual partners) with history of unspecified hepatitis (AOR: 13.8; 95% Cl: 4.25.2), and insertive anal penetration (AOR: 5.1; 95% Cl: 1.6-16.7) were independently associated with infection.

Conclusion: Based on the relatively low HAV prevalence, the high prevalence of risk factors for infection, and the substantial hepatitis B and C prevalence, vaccination against hepatitis A is now actively promoted among Montreal street youth.

In countries with a low incidence of hepatitis A virus infection (HAS, outbreaks regularly occur among injecting drug users (IDUs) and homosexual men.1 In 1995-96, we conducted a study on the prevalence of hepatitis B and C among street youth in Montreal (hepatitis B: 9.2%; hepatitis C: 12.6%).2,3 Towards the end of the study, the Montreal Regional Public Health Department observed an outbreak of hepatitis A among gay men. Given the high proportion of male street youth having had sex with other men (15.5%) and the high proportion of IDUs (45.8%) among these youth,25 we decided to document the prevalence of hepatitis A among street youth. We conducted a secondary analysis, using blood samples left over from the hepatitis B and C study (youth involved had agreed on the consent form to analysis of leftover specimen).

The methods of this study have been described in detail in a previous publication.2 In brief, "street active" participants aged 14 to 25 years were recruited through the ongoing Montreal Street Youth Cohort Study.' Youth were considered 11 street active" if they had either been without a place to sleep more than once or had regularly used the services of Montreal street youth agencies during the previous year. The cohort study was approved by the Human Subjects (Ethics) Committee, Department of Epidemiology and Biostatistics at McGill University.

All youth completed a 15-minute faceto-face questionnaire on socio-demographic characteristics and lifetime risk factors and gave a blood sample. Anti-HAV antibody testing using Roche Cobas Core anti-- HAV EIA (Roche Diagnostics Systems, Mississauga, Ontario, Canada) was conducted on samples from 427 study participants. This competitive test has a cut-off value of 140 mUI/ml.

The overall prevalence of HAV antibodies was 4.7% (20/427) with a 95% confidence interval of 2.9% to 7.2%. The prevalence did not vary significantly with sex (8.8% for women vs 5.1% for men, p=0.543), while HAV-seropositive subjects were older than seronegative ones (21.0 vs 19.4 years, p=0.007). Among other relevant results, we found that HAV prevalence was not associated with oro-genital intercourse or with injection drug use. The lifetime variables presenting the strongest association with HAV prevalence in univariate analyses were: birth in a country with a high anti-HAV prevalences (70.0% vs 3.1%, p<0.001); sexual activities with a person with a history of unspecified hepatitis (18.9% vs 3.4%, p=0.001), with a female prostitute (8.8% vs 3.2%, p=0.016), or with an HIV-infected person (17.4% vs 4.1%, p=0.020); having lived with someone (other than a sexual partner) infected with an unspecified hepatitis (13.2% vs 3.1%, p=0.002); and insertive anal penetration (11.1% vs 3.6%, p=0.018).

Table I presents the three factors independently associated with HAV infection in a multivariate logistic regression analysis.

Our data indicated frequent co-infections. …