1 in 6 Gay Men Recently Infected
posted: 26/07/2010
One in six gay men having a HIV positive test in the UK became HIV positive within the past six months. This is the first result from a new system tracking trends in recent HIV infections in the UK.
The Health Protection Agency devised a formula (an algorithm) and method for tracking recent HIV infections. Knowing how many people were recently infected is helpful for working out what is actually happening in the UK HIV epidemic.
The number of recent infections matters because people who are recently infected are far more infectious than at any other time.
Tracking recent infections
The new formula and tracking method, called either the Recent Infection Testing Algorithm (RITA) or Serological Testing Algorithm for Recent HIV Seroconversion (STARHS), measures the amounts of certain antibody markers. These amounts change depending on how long ago the HIV infection took place. Amounts below a certain level mean the infection was recent (approximately within the last six months).
The RITA / STARHS method is not exact enough to tell an individual when they became HIV positive, because we all vary in how our immune system responds to HIV, but the method is good enough to give rough timings, which is all we need to track what is happening with the epidemic.
The work on this tracking system began in 2008, when the Health Protection Agency rolled-out STARHS as part of the routine public health monitoring of all newly diagnosed HIV infections in the country.
Results
The data presented the International AIDS 2010 conference in Vienna that has just ended, came from samples of 2099 people, who broadly represent, demographically and geographically, people newly diagnosed in the UK. The samples were collected between February 2009 and May 2010.
Gay and bi men results
Amongst gay and bisexual men, 16.1% of diagnoses were judged to be recent – within the past six months – one in six. There wasn’t any difference between gay and bi men of different ages.
Heterosexual results
Among heterosexuals, 6.2% men and 6.8% women were recently infected. This is just one in sixteen heterosexuals being infected within six months of their positive test.
There appears to be a trend for recent infections to be more commonly identified in younger heterosexual women (probably due to antenatal testing), but the age variations were not statistically significant. Curiously, in women aged 50 or over, there was a relatively high proportion of recent infections, but this is based on a small number of cases and could be due to chance. But it fits with another recent report from the HPA at the Vienna International AIDS Conference - many long-term heterosexual relationships break up when people are in their 50s, and women, no longer needing contraception, may neglect to consider the need for safer sex - condoms - to protect against STIs such as HIV.
Recently infected heterosexuals were largely people born in the UK. Heterosexual people born in Africa tend to have infection diagnosed later, the majority becoming HIV positive before migration to the UK.
Source
Reference: Lattimore S et al. Surveillance of recently acquired HIV infections among newly diagnosed individuals in the UK. Eighteenth International AIDS Conference, Vienna, abstract FRAX01001, 2010.
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