Abstract
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 Bendemic countries. J. Med. Virol. 66:159–165, 2002. © 2002 Wiley‐Liss, Inc.