An outbreak of HIV-1 subtype G among Italian injecting drug users.

We describe an outbreak of subtype G among injecting drug users (IDU) in northern Italy newly infected with HIV We analysed pol gene sequences from samples of 139 individuals from different risk groups. Non-B subtypes were more frequently detected among IDU than in homosexual or heterosexual contacts. All G subtypes but one were found among IDU. The phylogenetic analysis indicated that the outbreak was of monophyletic origin and was caused by HIV-1 strains similar to those from western Africa.