Different HIV rates among gay men and straight people not fully explained by sexual behavior

Sep 13, 2007

Differences in sexual behaviours do not fully explain why the US HIV epidemic affects gay men so much more than straight men and women, claims research published ahead of print in the journal Sexually Transmitted Infections.

In 2005, over half of new HIV infections diagnosed in the US were among gay men, and up to one in five gay men living in cities is thought to be HIV positive.

Yet two large population surveys showed that most gay men had similar numbers of unprotected sexual partners per year as straight men and women.

US researchers applied a series of carefully calculated equations in different scenarios to study the rate at which HIV infection has spread among gay men and straight men and women.

They used figures taken from two national surveys to estimate how many sex partners gay men and straight men and women have, and what proportion of gay men have insertive or receptive anal sex, or both.

They then set these figures against accepted estimates of how easily HIV is transmitted by vaginal and anal sex to calculate the size of the HIV epidemic in gay men and straight men and women.

The results showed that for the straight US population to experience an epidemic of HIV infection as great as that of gay men, they would need to average almost five unprotected sexual partners every year.

This is a rate almost three times that of gay men.

But to end the HIV epidemic, gay men would need to have rates of unprotected sex several times lower than those currently evident among the straight population. This is because transmission rates are higher for anal sex than they are for vaginal sex, say the authors.

But "role versatility," whereby people adopt both “insertive” and “receptive roles,” also plays a part, they add.

A gay man can be easily infected through unprotected receptive sex, and then infect someone else through insertive sex.

Gay men are therefore far more susceptible to the spread of the virus through the population, even with the same numbers of unprotected sexual partners.

Source: BMJ Specialty Journals

Explore further: Liberia shuts schools in battle against Ebola: president

add to favorites email to friend print save as pdf

Related Stories

Microsoft unveils Xbox in China as it faces probe

55 minutes ago

Microsoft on Wednesday unveiled its Xbox game console in China, the first to enter the market after an official ban 14 years ago, even as it faces a Chinese government probe over business practices.

Classic Lewis Carroll character inspires new ecological model

57 minutes ago

Inspired by the Red Queen in Lewis Carroll's Through the Looking Glass, collaborators from the University of Illinois and National University of Singapore improved a 35-year-old ecology model to better understand how species ...

Recommended for you

Fatigue, fear are daily lot of Ebola fighters: experts

8 hours ago

Doctors, nurses and hospital workers fighting the Ebola epidemic in west Africa are struggling with a daily burden of exhaustion, shortage of staff and fear for themselves over the deadly virus, specialists say.

Hong Kong makes Ebola 'contingency' measures

11 hours ago

Hong Kong said Wednesday it was quarantining all people from Guinea, Sierra Leone and Liberia who were showing Ebola-like symptoms on arrival in the city, as fears grow worldwide about the spread of the deadly virus.

User comments : 0