Molecular epidemiology of hepatitis B virus in Amsterdam 1992-1997

To gain insight into the spread of hepatitis B among various risk groups in Amsterdam a 6-year (1992-1997) retrospective DNA sequencing study was carried out on isolates from stored sera from reported primary cases of acute hepatitis B infection. Cases were classified according to risk behavior, as determined in interviews. Of the available serum, a selected region of hepatitis B-virus-DNA was amplified and sequenced. The nucleotide alignments were subjected to phylogenetic tree analysis. When nucleotide alignments were subjected to phylogenetic analysis, the strains of 54 isolates, 26% of the 204 reported primary cases, clustered in five genotypes: A, C, D, E, and F. In genotype A, a cluster related to men having sex with men was identified. In genotype D, two subclusters could be identified: one was related to injecting drug use and another was related to the Moroccan population in Amsterdam. The remaining strains showed a high genetic variability within three different genotypes: F, E, and C. Of the 14 identical isolates in the "homosexual men cluster," one was isolated from a female heterosexual. Of the 14 identical strains in the "drug users strain," six were from non-drug using heterosexual active individuals. In the cluster of twelve isolates related to hepatitis B-endemic areas, probable modes of transmission were varied. Sequence analysis provides important insight into the spread of hepatitis B among various high-risk groups. The analysis indicates that the prevention strategy in The Netherlands fails to stop transmission of hepatitis B from persistently infected individuals originating from hepatitis B endemic countries.