Researchers Explain Why Male Circumcision Decreases HIV Risk, But Practice Still Has Critics

A new study reports that types of bacteria able to thrive on a man's penis are drastically altered by circumcision, which may explain why circumcision often protects against HIV and other infections, the researchers state. But the practice still has critics, who say circumcising males can infringe on the right to physical integrity as well as decrease sexual pleasure.

Researchers studied the effects of adult male circumcision on the types of bacteria that live under the foreskin before and after circumcision. By one year post-procedure, the total bacterial load in that area had dropped significantly and the prevalence of anaerobic bacteria, which thrive in locations with limited oxygen, declined while the numbers of some aerobic, or oxygen-dependent, bacteria increased slightly.

"There was a dramatic and significant change in the penis microbiome as a result of male circumcision," said study author Lance Price of the Translational Genomics Research Institute in Flagstaff, Ariz.

"From an ecological perspective, it's like rolling back a rock and seeing the ecosystem change. You remove the foreskin and you're increasing the amount of oxygen, decreasing the moisture - we're changing the ecosystem."

According to a release by the American Society for Microbiology, randomized controlled trials show that circumcision reduces the risk of HIV infection in men by as much as 60 percent, but the biology behind these benefits is not well understood. Some studies suggest that genital bacteria may affect how susceptible the penis is to sexually transmitted viral infections.

Price and colleagues used swab samples from a large circumcision trial in Uganda to examine the microbial community in the penis. The researchers compared samples from uncircumcised men with samples from circumcised men that were taken both before the procedure and one year later.

Despite the medical evidence behind the benefits of male circumcisions, there is, however, a growing global resistance to male circumcision from a vocal opposition who associate the practice with decreased sexual pleasure and an infringement of the right to physical integrity.

Last year a German court ruled that a child's right to physical integrity trumps the parents' right religiously circumcise a boy, deeming circumcision of minors for non-medical reasons a criminal offense. The ruling was later overturned by a law passed by Germany's parliament to keep the practice of circumcising boys legal. 

Earlier this year, Reuters reported on a study from Belgium that found men circumcised either as boys or adults reported less intense sexual pleasure and orgasm than their uncircumcised counterparts.