One in three HIV positive gay men don't know they are infected with the virus, suggests a large community study published in Sexually Transmitted Infections.
The proportion of gay men who said they had had unprotected anal sex in the previous year has also been steadily rising, the study shows.
The findings are based on anonymous questionnaires completed by over 8000 men between 1996 and 2000. All the men were recruited from up to 58 social venues each year in London, including bars, clubs, and saunas.
In 2000, saliva samples were provided by 1206 of the men, to test their HIV status. Analysis of the responses showed that the proportion of men who said they had had unprotected sex within the previous 12 months rose significantly each year.
In 1996, around one in three men reported this (30 percent). By 2000, this figure had risen to more than four out of 10 (42 percent).
One in nine (10.9 percent) of the 1200 saliva samples was positive for HIV. A third of these cases (43 out of 132) were undiagnosed. Of the men who said they knew their HIV status, 4 percent got it wrong.
Around half of both diagnosed and undiagnosed men said that they had had unprotected sex within the previous year.
Men who tested positive for HIV were twice as likely to have had a sexually transmitted infection in the previous year, and they were more likely to have had more than one partner with whom they had unprotected sex.
"The high level of risky behavior in HIV positive men, regardless of whether they are diagnosed, is of public health concern, in an era when HIV prevalence, antiretroviral resistance, and [sexually transmitted infection] incidence are increasing," conclude the authors.
To view the paper in full, go to http://press.psprings.co.uk/sti/june/236_st7286.pdf
Source: British Medical Journal