Two decades of hepatitis B infections among drug users in Amsterdam: are they still a high-risk group?

Abstract

In general, little is known about the incidence of hepatitis B virus (HBV) among drug users, especially among non-injecting drug users. Therefore, changes in incidence, risk factors, and circulating genotypes over time were determined among drug users in Amsterdam over an 18-year period (1985-2002). Sera of 1,268 drug users, both injecting and non-injecting, were screened for anti-HBc. HBV genotypes of the anti-HBc seroconverters were determined. Poisson regression was used to test for temporal trends in incidence and to identify risk factors for seroconversion. Of the 598 participants who were anti-HBc negative at entry, 83 seroconverted for anti-HBc. The incidence of HBV declined from 5.9/100 Person Years up to 1993 to 0/100 Person Years in 2002. Of the drug users infected acutely, both injecting and non-injecting, 88% were infected with the same genotype D, serotype ayw3 strain. Multivariate analyses revealed current injecting, age, and calendar year of visit as independent risk factors. The decline in the incidence of HBV among drug users in Amsterdam is probably caused by a decline in injecting behavior. Injecting and non-injecting drug users were infected with the same strain, indicating that drug users infect one another, regardless of their risk behavior. After 2000, no injecting drug users with an acute HBV infection were reported to the Public Health Service Amsterdam and the specific genotype D strain had disappeared. These findings suggest that drug users may no longer be a high-risk group for HBV infection in Amsterdam. However, trends in drug use need to be monitored.