LGV cases almost triple in one year; UK public health officials warn against serosorting

The number of gay men infected with the sexually transmitted infection lymphogranuloma venereum (LGV) has almost tripled in one year, and the UK now has the world’s worst epidemic of LGV, the Health Protection Agency reported today. At the same time, the agency is tracking an outbreak in gay men of shigellosis, a bacterial infection that is transmitted through contact with tiny amounts of human faeces.

The HPA suspects that transmission of both infections is being fuelled by serosorting behaviour, in other words men choosing to have unprotected sex with men who have the same HIV status as themselves. While HIV-positive men who serosort may avoid passing on their HIV infection, they still risk acquiring unpleasant and often serious sexually transmitted infections such as LGV, shigella and hepatitis C. Serosorting “is unsafe”, the HPA says.

LGV is a previously rare sexually transmitted infection, seen in UK gay men since 2003. It is caused by specific strains of Chlamydia. If left untreated, symptoms can be complex and severe, including proctitis (inflammation of the anus or rectum).

Diagnoses of LGV increased from 190 in 2009 to 530 in 2010. Of the total 1560 cases seen between 2003 and 2010, more than one third have been diagnosed since the beginning of 2010.

The vast majority (83%) of LGV cases were in HIV-positive gay men. The infection is thought to be transmissible during unprotected anal intercourse, an activity which 84% of infected men report. Two-thirds of diagnoses were in London, but there are cases from across the country, especially Brighton and Manchester.

The public health agency is also concerned about a smaller outbreak of shigellosis. This bacterial infection, caused by either Shigella sonnei or Shigella flexneri has only occasionally been seen in UK gay men. The symptoms of shigellosis can include severe and bloody diarrhoea, but it can be successfully treated with antibiotics.

Shigella is transmitted by contact with tiny amounts of faeces. This can occur as a consequence of poor hygiene, or may be linked to sex, especially rimming, fingering, fisting, anal sex, and handling used sex toys and douching equipment. The bacteria may pass from dirty fingers to the mouth; basic hygiene and handwashing habits reduce the risk of transmission.

There have been 29 cases of infection with Shigella flexneri recorded since May 2011, mostly in London or Manchester. The HPA have not yet identified the key characteristics of the men who have been infected or identified the shared use of specific venues. However some previous shigellosis outbreaks have been concentrated in men with HIV and in men who used sex-on-premises venues.

The HPA report also notes the ongoing epidemic of sexually acquired hepatitis C in gay and bisexual men with HIV - 228 cases of recent infection were recorded at 22 of the larger HIV clinics in 2008-2010.

In addition, new diagnoses of the more widespread infections chlamydia and gonorrhoea are higher than they have been for more than a decade, at around 4500 and 5000 diagnoses respectively.

The HPA believes these figures highlight the dangers for HIV-positive men of ‘serosorting’, in other words having unprotected sex with partners thought also to be HIV-positive. “Serosorting poses a risk of acquiring other STIs and hepatitis, with serious treatment implications,” the agency warns.

It does not encourage HIV-negative men to serosort either, because rates of undiagnosed HIV are high. One quarter of those infected do not know that they have HIV.