More than 40 percent of gay men were unaware they had HIV in a study of anonymous testing in five U.K. cities, Aidsmap reports ( 6/10)

Investigators in Glasgow and London examined links between sexual risk behavior, HIV testing history and HIV prevalence in London, Brighton, Manchester, Glasgow and Edinburgh.

The investigators found that both diagnosed and undiagnosed HIV-positive men reported significantly more sexual partners, more high-risk sex, and more sexually transmitted infections in the previous year than did HIV-negative men.

“Our findings suggest that relying on a past HIV-negative test result, even within the previous year, may be an ineffective prevention strategy without the additional interventions of condom use and reduced partner numbers,” researchers said.

Contrasted with HIV-negative men, the odds were significantly higher for both undiagnosed and diagnosed men of having 10 or more sexual partners and having two or more unprotected anal intercourse partners.