Penile washing directly after sex increased the risk of acquiring HIV: circumcision effective for men in high prevalence populations no protective effect in gay men
Simon Collins, HIV i-Base
Several studies adding to the already important data showing the effectiveness of male circumcision on a population level in areas of high HIV prevalence. The oral session on this subject is available online, and slides are available to download. 
Effectiveness, and cost effectiveness is recognised [2, 3], and sessions also focused on how to safely integrate this with other prevention programmes. 
Useful data on other aspects of transmission were also detailed at IAS.
Firstly, analysis of an Australian cohorts of gay men did not show circumcision to have a protective or negative impact on risk of HIV tranmission. 
This is probably related to the limited numbers of participants who are exclusively active or passive.
A second important study, presented by Frederick Makumbi from Makerere University, Kampala, and colleagues, produced evidence from a sub-study of the Rakai circumcision study, that men who washed their penis immediately after sex (within three minutes) were at significantly higher risk of catching HIV compared to men who didnt wash, or who delayed washing by at least ten minutes.
This information challenges common sense, and believed sense, and common practice.
2552 HIV-negative uncircumcised men enrolled in the control arm of a male circumcision study were also interviewed about post-coital penile hygiene (washing the penis after sex, use of a dry cloth or washing or both) and the time from intercourse to cleansing after sex.
In almost 4400 follow-up intervals during which men reported being sexually active, men reported post-coital cleansing with all partners in over 80% of occassions. Although HIV incidence among men reporting cleansing with all partners (1.69/100py) compared to those never cleansing (1.22/100py) was higher, this was not statistically significant (adj.RR=1.20; 95%CI: 0.42-3.38). However, among those reporting post-coital cleansing with all partners, 49.2% cleaned within 3 minutes. HIV incidence was significantly higher among those reporting cleansing within 3 minutes (2.32/100 py), compared to those reporting a delay of more than 10 minutes (0.39/100py, adj.RR= 0.13; 95%CI: 0.03 0.54).
HIV incidence was also higher among those reporting washing-alone (2.20/100 py), than those reporting use of a cloth and washing (1.04/100 py) and those using a cloth-alone (0.55/100 py, c2 for trend p=0.0442).
A trend to increased risk with borderline significance was shown with increased wetness of washing.
Four mechanisms were proposed to explain these findings:
i) that the acid pH of vaginal secretions may impair HIV survival ii) that the use of water with a neutral pH, may facilitate viral survival and possible infectivity, iii) that washing of any kind, or use of soap, may contribute to micro ulceration that facilitates infection, and iv) that delayed cleansing may reduce viral infectivity by prolonged exposure to acidic vaginal secretions.
While limitations include difficulties of self-report sexual practices and lack or detail (on use of soap, type of soap and washing etc), these finding deserve further study on both a clinical and epidemiological level.
Other recent studies showed an increased risk for HIV in women who cleansed using soap or water , but a protective effect for circumcised men who washed. 
Unless stated otherwise, references are to the 4th IAS conference on HIV Pathogenesis, Sydney, 2007.
- Male circumcision: the cutting edge of prevention. Oral abstract session WEAC1.
- Londish G, Murray J. Mathematical modelling of male circumcision in sub-Saharan Africa predicts significant reduction in adult HIV prevalence even when it is limited to certain age groups. Abstract WEAC104.
- Auvert B. Cost of the roll-out of male circumcision in sub-Saharan Africa. Abstract WEAC105.
- Kigozi G, Gray R, Wawer M et al. The safety of adult male circumcision in HIV-infected and uninfected men in Rakai, Uganda. Abstract WEAC101.
- Templeton DJ, Jin F, Prestage GP et al. Circumcision status and risk of HIV seroconversion in the HIM cohort of homosexual men in Sydney. Abstract WEAC105.
- Makumbi FE, Gray RH, Wawer M et al. Male post-coital penile cleansing and the risk of HIV-acquisition in rural Rakai district, Uganda. Abstract WEAC1LB.
- McClelland SR et al. Vaginal washing and increased risk of HIV-1 acquisition among African women: a 10-year prospective study. AIDS 2006, 20:269273.
- Meier SA et al. Independent Association of Hygiene, Socioeconomic Status, and Circumcision With Reduced Risk of HIV Infection Among Kenyan Men. J Acquir Immune Defic Syndr & Volume 43, Number 1, September 2006.