The investigators also note that twelve men were first diagnosed with HIV at the same time as rectal infection with chlamydia was detected.įactors significantly associated with rectal chlamydia were HIV infection (p < 0.01), rectal gonorrhoea (p = 0.0002) and genital warts (p = 0.016). There was a high prevalence of HIV infection in men with rectal chlamydia (38%, 94 individuals). The vast majority of rectal LGV cases (82%) were symptomatic. Rectal LGV was diagnosed in 14% (35) of the men with rectal chlamydia. Only 8% of asymptomatic men also had urethral infection. Rectal infection with chlamydia was asymptomatic in 69% (171) of the men and would therefore have been missed without routine screening. Of the 397 men diagnosed with chlamydia, 62% (247) were infected rectally, 42% (165) had urethral infection and 4% (15) had the infection in both sites. The investigators then looked at the cases of chlamydia in more detail. The prevalence of chlamydia was higher than any other infection, with tests showing that 4% of men had rectal gonorrhoea, 5% had urethral gonorrhoea and 3% syphilis. Results showed that 8% of men had rectal chlamydia, with 5% having urethral chlamydia. All these men had urethral screens for chlamydia and 3017 had rectal swabs for the infection. The study was conducted between 20 and included a total of 3076 men.
Most of the cases have involved rectal infection.
LGV is caused by certain strains of chlamydia. In recent years, outbreaks of the sexually transmitted infection lymphogranuloma venereum (LGV) have been observed in gay men in the UK and several other industrialised countries. Therefore the investigators reasoned that a benefit of detecting and treating rectal chlamydia would be a reduction in onward HIV transmission. Chlamydia, like all sexually transmitted infections, can cause changes to the genital mucosa that increase the risk of HIV transmission. Previous studies have found that between 7 and 9% of gay man attending sexual health clinics have rectal infection with chlamydia, and that such infections are often without symptoms.