IAS: Penile washing after sex not a substitute for circumcision

Cleaning the penis after vaginal sex does not protect a man from infection with HIV, according to a study conducted in Rakai, Uganda and presented as a ‘late breaker’ in the circumcision session at the Fourth International AIDS Society Conference in Sydney on July 25^th.

Dr Fredrick Makumbi of Makerere University Institute of Public Health, Uganda, who presented the study, said that his study team had been surprised by this finding given that genital hygiene has long been thought to be protective against sexually transmitted infection. He emphasised that men who washed using soap, or a few minutes after intercourse had the highest risk of infection with HIV.

He speculated that this could be because washing with soap and failure to dry resulted in wetness, increasing the chance of cells becoming inflamed and thus more vulnerable to infection with HIV. Dr Makumbi also suggested that washing soon after sex could remove enzymes in vaginal fluid that help neutralise HIV.

Three randomised controlled trials in Africa have shown that men who are circumcised have a lower risk of becoming infected with HIV. However, circumcision is not universally possible or acceptable, and genital hygiene has been suggested as an alternative.

Therefore, investigators from the large Rakai circumcision trial analysed data from 2,552 uncircumcised, HIV-negative men to establish if post-coital washing helped to protect men against infection with HIV.

Investigators interviewed men about their cleaning habits after they have sex. This was correlated to the incidence of HIV seroconversion during the study.

During a total of 4,378 follow-up interviews, 83.0% of men reported cleaning after each time they had sexual intercourse. The HIV incidence in this group was not significantly different to that in the group who never cleaned, 1.69 per 100 patient years versus 1.22 per 100 patient years, respectively.

When men who cleaned were asked how soon after intercourse they usually cleaned, almost half (49.2%) responded that they clean within three minutes.

In this group of men, HIV incidence was 2.32 per 100 patient years. This was significantly higher than the incidence of 0.39 per 100 patient years among men who waited at least 10 minutes after sex before cleaning. That is to say that waiting 10 minutes before cleaning decreased the HIV incidence to less than 20% of that among men who washed right away.

Differences were also noted in HIV incidence depending on what cleaning method was used. Washing only, reported in 46.9% of interviews, was associated with an incidence of 2.20 per 100 patient years. Using a cloth and washing was used in 40.6% of cases and was associated with an incidence of 1.04 per 100 patient years. And using only a dry cloth, 12.4% of cases, was associated with the lowest incidence, 0.55 per 100 patient years (p = 0.0442).

In conclusion, the authors noted that while cleaning the penis after sex is common in this rural Ugandan population, caution should be taken in promoting it as an alternative to circumcision.