Unprotected receptive anal sex is the key risk factor for rectal LGV (lymphogranuloma venereum) infections in gay and other men who have sex with men (MSM), UK researchers report. Their case-controlled study published in the online edition of Sexually Transmitted Infections also showed that 89% of people with LGV were HIV positive. Fisting and drug use were also identified as risk factors for infection.
“Campaigns to raise awareness of LGV and of the symptoms among gay men, particularly HIV-positive men, should be updated and maintained,” write the authors. “Sexual health clinics should identify men at risk, encourage frequent STI screening, provide adequate treatment and contact tracing, and offer appropriate support to minimise the risks associated with sexual behaviour and substance use.”
LGV is a bacterial STI caused by strains of Chlamydia. It is associated with invasive, ulcerative disease and can be cured with a 21-day course of antibiotic therapy.
There is an ongoing epidemic of LGV among gay men in the UK. Although the first cases were recorded as long ago as 2003, there is still uncertainty about its risk factors.
A team of UK investigators therefore designed a case-controlled study involving six treatment centres in Brighton, Glasgow and London, all with high LGV caseloads. The study population was restricted to men reporting sex with other men.
The cases (n = 90) were men with confirmed rectal LGV infection. There were two types of controls: men with rectal symptoms possibly associated with LGV (n = 74) and asymptomatic men without such symptoms (n = 69). Participants were recruited between August 2008 and December 2010.
Study participants provided details of their HIV infection status, recent sexual behaviour and use of recreational drugs.
Participants had a median age of 39 years. HIV prevalence was significantly higher among the cases (89%), compared to both the symptomatic (48%) and asymptomatic (68%) controls.
In terms of sexual behaviour, cases were significantly more likely than asymptomatic controls to report being fisted (22 vs 1%; p < 0.001), fisting another man (37% vs. 4%; p < 0.001), unprotected receptive anal sex (93% vs. 43%; p < 0.001) and unprotected insertive anal sex (85% vs. 46%; p < 0.001).
The cases were also more likely than the asymptomatic controls to report more than ten recent sexual partners (45 vs 24%; p = 0.006) and having anonymous partners (57 vs 30%; p = 0.001).
Approximately a third of cases, but only 16% of the asymptomatic controls, said they had met partners at a sex party (p = 0.024).
Cases were also more likely than the asymptomatic controls to report the use of certain recreational drugs, especially GHB/GBL (57 vs 21%; p < 0.001) and methamphetamine (46 vs 10%; p < 0.001).
After controlling for confounding factors, the investigators identified receptive unprotected anal sex (AOR = 10.7; 95% CI, 3.5-32.8; p < 0.001), fisting another man (p = 0.005), anonymous sex (p = 0.20) and sex under the influence of GHB/GBL (p = 0.011) as risk factors for confirmed rectal LGV infection in comparison with asymptomatic men.
The authors then compared the characteristics of the confirmed cases with those of the symptomatic controls.
The cases were more likely to report receptive unprotected anal sex (93 vs 68%; p < 0.001); insertive fisting (80 vs 56%; p = 0.002), more than ten recent sexual partners (45 vs 28%; p = 0.026), rectal douching to prepare for sex (84 vs 54%; p < 0.001), use of GHB/GBL (57 vs 32%; p = 0.002), use of methamphetamine (46 vs 20%; p = 0.001), group sex (49 vs 27%; p = 0.018), unprotected anal intercourse with an HIV-positive partner (78 vs 45%; p < 0.001) and sero-concordant unprotected anal intercourse between HIV-positive partners (74 vs 40%; p < 0.001).
Independent risk factors were unprotected insertive anal sex and rectal douching.
“We identified unprotected receptive anal intercourse as a key risk factor for rectal LGV infection in MSM,” write the authors. “This finding, although not unexpected, supports the hypothesis that rectal infection is due to direct inoculation…this can occur either directly from men with urethral infection, or indirectly by transfer from another infected rectum on a covered or uncovered penis, sex toy or finger without the insertive partner necessarily having LGV infection.”
They believe their findings have implications for LGV prevention campaigns, supporting “advice that condoms provide protection against LGV, and that particular care is required in group sex situations”.
MacDonald N et al. Risk factors for rectal lymphogranuloma venereum in gay men: results of a multicentre case-control study in the UK. Sex Transm Infect, online edition ahead of print, doi: 10.1136/sextrans-2013-051404.