Circumcision may lower risk of genital wart virus

Circumcision has been found to lower men's risk of contracting HIV through heterosexual sex, and now new findings suggest that it also cuts the risk of infection with the human papillomavirus (HPV) in both HIV-positive and HIV-negative men.

The findings, from two studies in Uganda, suggest there may be additional benefits to offering circumcision to men in countries with high rates of heterosexual HIV transmission.

What the findings could mean for other countries, including the U.S., is less clear, researchers say.

In 2005 and 2006, three clinical trials in Uganda, South Africa and Kenya showed that circumcision can cut a man's risk of HIV infection through heterosexual sex by up to 60 percent. Subsequent studies of those men also found a lower prevalence of HPV among those who were circumcised and HIV-negative.

But it hadn't been clear whether that lower prevalence was specifically due to a lower risk of HPV infection. Nor has it been known whether circumcision affects HPV risk in HIV-positive men, according to Dr. Ronald H. Gray, a professor at Johns Hopkins University School of Public Health in Baltimore and the senior researcher on the Ugandan studies.

HPV is a highly common virus with more than 100 strains, some of which cause genital warts. While the immune system clears the infection in most people, persistent infection with certain HPV strains can lead to cancer. HPV is the primary cause of cervical cancer in women, and it can also lead to penile and anal cancers.

Gray noted that HPV-related cancers are a serious public health problem in sub-Saharan Africa - in contrast to developed countries, where, for example, women have access to regular Pap tests to detect cervical cancer early and, in recent years, HPV vaccination.

Moreover, people with HIV infection often have HPV infections as well, and are especially susceptible to developing HPV-related cancers, Gray said.

The current studies, published in the Journal of Infectious Diseases, found that circumcision appeared to lower the rate of infection with cancer-related HPVs in both HIV-negative and HIV-positive men - by 33 percent and 23 percent, respectively, compared with uncircumcised men.

The studies included 210 HIV-positive and 840 HIV-negative men between the ages of 15 and 49 who were randomly assigned to undergo immediate or delayed circumcision. At the outset, 39 percent of HIV-negative and roughly three-quarters of HIV-positive men carried at least one cancer-related strain of HPV.

Circumcision appeared to lower the men's rates of new high-risk HPV infections, and, in HIV-negative men, it increased the rate at which their immune systems cleared established infections. Still, after two years, many circumcised men were still found to carry a cancer-related HPV: more than 20 percent of HIV-negative men and 55 percent of HIV-positive men.