PREVALENCE OF HEPATITIS-B VIRUS (HBV) INFECTION IN SINGAPORE MEN WITHSEXUALLY-TRANSMITTED DISEASES AND HIV-INFECTION - ROLE OF SEXUAL TRANSMISSION IN A CITY-STATE WITH INTERMEDIATE HBV ENDEMICITY

Study objectives - To describe the prevalence of hepatitis B virus (HB V) infection in patients with sexually transmitted diseases (STD) and human immunodeficiency virus (HIV) infection, and to determine the rol e of sexual transmission of HBV infection in Singapore. Design - A cro ss sectional study of all consecutive men presenting with a new episod e of STD at a government outpatient clinic and all men with HIV infect ion on routine follow up at a government hospital. The prevalence of v arious HBV markers was compared with that of healthy males aged 15 yea rs and above (controls). Setting - Singapore, a city state of intermed iate HBV endemicity. Subjects - These comprised 497 STD patients, 47 H IV infected patients, and 418 controls. Main results - The overall ser oprevalences of HBV infection in STD patients, HIV infected patients, and control subjects were 41.2%, 61.7%, and 33.3%, respectively (p < 0 .001). The seroprevalences of hepatitis B surface antigen (6.2%, 8.5%, and 4.5%, respectively) were comparable in the three groups. Using st epwise logistic regression analysis, the adjusted seroprevalences of H BV infection in STD and HIV infected patients were respectively 2.4 ti mes (95% confidence interval (CI), 1.7, 3.3) and 3.3 times (95% CI 1.7 , 6.3) higher than in controls. HBV infection rates were higher among Chinese (odds ratio (OR), 1.9; 95% CI 1.6, 3.4) than non-Chinese, and among those aged 25-34 years (OR 2.4; 95% CI 1.6, 3.4), 35-44 years (O R 3.9; 95% CI 2.5, 5.9), and 45 + years (OR 6.2; 95% CI 3.8, 10.2) tha n in those aged 15-24 years. Sex related factors significantly associa ted with higher infection rates, independent of age and ethnic group, were Pathology reactive VDRL test (OR 2.4; 95% CI 1.2, 4.7), participa tion in analintercourse (OR 2.3; 95% CI 1.2, 4.3), and having 10 or mo re lifetime sexual partners (OR 1.5; 95% CI, 1.0, 2.1). Conclusion - T he importance of sexual transmission of HBV in an area of intermediate HBV endemicity was confirmed. Patients routinely screened for HBV mar kers and those found to be seronegative should be strongly advised to be immunised against this virus.