The spread of HIV amongst Amsterdam’s gay men is being driven by men over 35 recently infected with HIV who also have an untreated sexually transmitted infection (STI), according to a Dutch study published in the 5 July edition of the journal AIDS.
To find out if reported increases in unprotected anal sex and increased incidence of STIs was resulting in the increased spread of HIV amongst gay men, investigators at the sexual health clinic of the Municipal Health Clinic in Amsterdam, the Netherlands, used an HIV testing technique which is able to distinguish between recent and longer-standing HIV infections. The technique uses the slow increase in HIV antibodies after infection, which causes the blood samples of people recently infected with the virus to be non-reactive to less sensitive HIV testing assays, whilst being positive in sensitive assays.
Between 1991 and 2001, 3090 gay men consented to give blood samples as part of the twice yearly unlinked anonymous HIV prevalence survey conducted at the Amsterdam sexual health clinic. At the same time, they were screened for sexually transmitted infections such as gonorrhoea and syphilis and were interviewed by researchers about their sex lives and social background. The average age of those participating in the study was 32 between 1991 and 1996, increasing to 35 in 1997-2001.
Blood samples were tested for HIV antibodies using a commercially available enzyme immunoassay, and confirmed by Western blot analyses. Positive specimens were then tested using less sensitive HIV enzyme immunoassays to determine which individuals had been recently infected. Samples which were non-reactive to this test, were further analysed for the presence of HAART.
Individuals who were reactive on the sensitive assay, but non-reactive on the less sensitive assay, were considered to have been infected with HIV in the past 170 days.
The investigators found that 14.7% (454 of 3090) of samples tested positive for HIV antibodies using the sensitive assays. Of these, 58 failed to react to the less sensitive assays, but anti-HIV drugs detected in 21 samples which were therefore discounted, leading the investigators to conclude that 37 men had been recently infected with HIV.
Of those recently infected, 83.8% were unaware that they had HIV, and over 70% had a concurrent STI. Infections such as gonorrhoea, syphilis, and herpes are not just possible indicators of sexual activity which carries a risk of HIV-transmission, but also increase the risk of being infected with, or passing on HIV.
In particular, the Dutch researchers noted suggestions that “individuals who are in the early phase of their HIV infection contribute considerably to the spread of HIV because HIV RNA levels, and thus infectiousness, are very high in this phase.” They suggest that their study supports this theory, as it showed “a large proportion of men with a recent HIV infection had a co-exisitng STD (sic), and that men with both conditions reported large numbers of recent sexual partners; factors likely to contribute to the risk of transmission of HIV and other STDs.”
In addition, the incidence of HIV appeared to be increasing amongst older gay men (aged 35 and above). The investigators noted that this finding is “contrary to previous years, when new infections largely occurred in younger men.”
The incidence of gonorrhoea and syphilis was also found to be increasing amongst Amsterdam’s gay men during the period of the study, with a three-fold increase in gonorrhoea diagnosed between 1997 and 2001 and a seventeen-fold increase in syphilis. Once again, older gay men were more likely to be infected with these diseases.
The study concludes that the “incidence of HIV is increasing among homosexual attendees of an Amsterdam STD clinic. Together with rising rates of syphilis, gonorrhoea, and related risk behaviour among homosexual men, this finding calls for preventative action, especially for those who have recently been infected.”
Reference: Dukers NHTM et al. HIV incidence on the increase among homosexual men attending an Amsterdam sexually transmitted disease clinic: using a novel approach for detecting infections. AIDS 16, 10:19-24, 2002.