Male circumcision doesn't protect against urethral STIs

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Circumcision does not protect men against urethral infection with the bacterial sexually transmitted infections gonorrhoea and chlamydia, according to the results of a randomised controlled trial published in the online edition of Sexually Transmitted Infections. However, the study showed that male circumcision offered some protection against trichomonas vaginalis and the investigators suggest that this could be one of the reasons why circumcision provides some protection against infection with HIV.

Results from the same study, conducted in Orange Farm, South Africa, have been published elsewhere and showed that male circumcision offers partial protection against HIV and human papilloma virus.

Gonorrhoea, chlamydia and trichomonas vaginalis are bacterial infections and cause a significant amount of illness in men and women around the world every year. Many of these infections are located in Africa.

Glossary

voluntary male medical circumcision (VMMC)

The surgical removal of the foreskin of the penis (the retractable fold of tissue that covers the head of the penis) to reduce the risk of HIV infection in men.

circumcision

The surgical removal of the foreskin of the penis (the retractable fold of tissue that covers the head of the penis) to reduce the risk of HIV infection in men.

chlamydia

Chlamydia is a common sexually transmitted infection, caused by bacteria called Chlamydia trachomatis. Women can get chlamydia in the cervix, rectum, or throat. Men can get chlamydia in the urethra (inside the penis), rectum, or throat. Chlamydia is treated with antibiotics.

odds ratio (OR)

Comparing one group with another, expresses differences in the odds of something happening. An odds ratio above 1 means something is more likely to happen in the group of interest; an odds ratio below 1 means it is less likely to happen. Similar to ‘relative risk’. 

randomised controlled trial (RCT)

The most reliable type of clinical trial. In a trial comparing drug A with drug B, patients are split into two groups, with one group receiving drug A and the other drug B. After a number of weeks or months, the outcomes of each group are compared.

As male circumcision has been shown to reduce the risk of HIV infection for men, investigators wished to see if it also had a protective effect against these bacterial urethral infections.

A sub-study of the Orange Farm randomised control trial of male circumcision as a method of HIV prevention was therefore designed.

Between 2002 and 2004 a total of 3274 young men were recruited to the main Orange Farm study and were randomised to be immediately circumcised or to have circumcision delayed until the end of the study’s 21 month follow-up. At intervals of three, twelve and 21 months the men had blood samples taken, a physical examination and provided details of their sexual behaviour.

For the sub-study, 1757 urine samples were collected to check for the presence of gonorrhoea, chlamydia and trichomonas vaginalis.

These samples showed that there was no difference in the proportion of circumcised (10%) and uncircumcised (10%) men with gonorrhoea. Nor was there any difference in the proportion of circumcised (3%) and uncircumcised (3%) men with chlamydia.

However, the investigators did find that circumcised men (2%) were significantly less likely than uncircumcised men (3%) (adjusted odds ratio, 0.47, 95% CI: 0.25-0.92, p = 0.027) to have urethral infection with trichomonas vaginalis.

“This study demonstrates that male circumcision does not have a protective effect on [chlamydia] acquisition for men”, comment the investigators, adding “no evidence of a protective effect of male circumcision on [gonorrhoea] infection was found.”

However, they note the protective effective of circumcision against trichomonas vaginalis. The investigators suggest that this could be because this infection affects the skin below the foreskin as well as the urethra.

“Thus the effect of male circumcision on HIV acquisition for young men may partly be due to its effect on trichomonas vaginalis”, write the investigators. They conclude that should their finding be supported by other randomised controlled trials currently underway, it would “reinforce the WHO-UNAIDS statement recommending the implementation of male circumcision programs in African countries with a low male circumcision prevalence and high male circumcision acceptability.”

References

Sobngwi-Tambekou J et al. Male circumcision and Neisseria gonorrhoeae, Chlamydia trachomatis, and Trichomonas vaginalis: observations in the aftermath of a randomised controlled trial for HIV prevention. Sex Transm Infect (online edition), 2008.