United Kingdom acquisition of HIV infection in African residents in London: more than previously thought.

Between a quarter to a third of HIV-positive African residents in the UK, and nearly half of HIV-positive African men who have sex with men, may have acquired their HIV infection in the UK, which is substantially higher than previously estimated. These estimates are likely to worsen given the increasing HIV prevalence and assortative sexual mixing in this community, especially among heterosexuals. HIV prevention interventions for Africans must focus on reducing transmission within the UK as well as addressing infections acquired abroad.