HIV and syphilis diagnoses among young gay and other men who have sex with men (MSM) increased in most metropolitan areas of the US between 2004 and 2008, investigators report in the online edition of the Journal of Acquired Immune Deficiency Syndromes.
The increase in diagnoses was especially marked in young (13-24) black men, among whom HIV diagnoses increased by 85% and syphilis diagnoses by 203%.
“Young black MSM have disproportionately high rates of HIV diagnoses…highlighting the need for prevention efforts which address the behavioral and structural factors that place these men at risk,” write the investigators.
A recent study using data from the Centers for Disease Control and Surveillance showed that although rates of new HIV diagnoses in the US are steady, they are increasing in young gay men and black men. Diagnoses of HIV and syphilis are especially high in younger black MSM.
However, it is possible that recent increases in reported rates of both infections have been skewed by large numbers of diagnoses in a few large cities. In 2008, two cities accounted for 20% of all cases of syphilis in gay men and a fifth of all HIV diagnoses in gay and other MSM were located in three cities.
Therefore, investigators analysed reported HIV and syphilis diagnoses in gay and other MSM from 73 metropolitan areas across the US. All had a population of at least 500,000, and to be included in the analysis the areas had to have a population of at least 500 black individuals aged between 13 and 14.
Rates of HIV and syphilis diagnoses between 2004 and 2008 were monitored. The results were stratified according to age and race.
The total number of HIV diagnoses in gay and other MSM increased between 2004 and 2008 in all 73 areas by an average of 11%. Over the same period syphilis diagnoses almost doubled (88%).
However, the largest percentage increase in HIV diagnoses was among black men aged 13 to 24. HIV diagnoses in all other age and race groups remained relatively stable.
A comparison of the 2004 and 2008 data showed that increases in HIV diagnoses in black MSM aged 13 to 24 occurred in 85% of the areas included in the study. Increases were observed in more areas for black men in this age group than for Hispanic (62%) or white (58%) MSM of a similar age.
The number of HIV diagnoses among young black MSM was 69% higher in 2008 compared to 2004.
Similar patterns were present for syphilis diagnoses. These increased in 70% of areas among black men aged 13 to 24. Overall, the number of syphilis diagnoses in young black gay men increased by 203% between 2004 and 2008.
The majority of areas (79%) had increases in both HIV and syphilis diagnoses in black men aged 13 to 24. Concurrent increases in HIV and syphilis diagnoses among Hispanic MSM in the same age group were recorded in 73% of areas, but concurrent increases in both infections among young white men occurred in only 50% of areas.
“These findings document that increases in HIV and syphilis diagnoses among young black men are not limited to a few large areas, but are widespread among areas with different population sizes,” comment the investigators.
They believe that some of the increase could be due to changes in US testing guidelines. In 2006, opt-out HIV testing was introduced and all individuals at high risk of HIV were recommended to have an annual HIV test. Moreover, in 2007 a major programme commenced designed to increase testing among African Americans.
However, the investigators also suggest: “increases in transmission may also explain the observed increases in diagnoses of HIV and syphilis.” They add: “the observed increase in HIV diagnoses among MSM aged 13-24 years suggests an increase in transmission.”
The investigators further argue that the massive increases in syphilis diagnoses point to high rates of risky sexual behaviour, commenting: “syphilis diagnoses can serve as a ‘real-time’ marker of unprotected sexual intercourse that may result in the transmission of syphilis or HIV.”
The authors were especially concerned about the especially large increase in new HIV diagnoses among younger gay men. They write: “young MSM report being unprepared for their first sexual encounter, such as being ill-equipped to negotiate safer sex or not knowing how to use lubricant to reduce tearing and bleeding during anal sex.”
Separate research has shown that sexual risk behaviour in among US is similar across racial groups. The investigators suggest that the especially large increase in new diagnoses among young black men in their study could be due to “social factors, such as sexual network configurations (e.g. sex with black and older partners).” They also note that rates of undiagnosed HIV are especially high among African Americans.
“Infections among young MSM are unacceptably high,” conclude the investigators, “as the underlying causes of the epidemic are likely to be multifactorial, combining multiple strategies may prove most beneficial in improving the sexual health of this increasingly vulnerable population.”