April 6, 2009

Circumcision Curbs Risk of Genital Herpes and HPV Infection

Photo of a man and woman of African descent

Adult circumcision can significantly reduce the risk of becoming infected with the viruses that cause genital herpes and genital warts, according to a large study of heterosexual men. The findings build on earlier research showing that male circumcision can greatly reduce the risk of HIV infection.

Genital herpes, caused by the herpes simplex virus type 2 (HSV-2), leads to painful genital ulcers. It's also been shown to boost the risk of HIV infection. Another common sexually transmitted virus, the human papillomavirus (HPV), can cause anal, cervical and penile cancers and genital warts. The prevalence of HPV infection has been rising, especially in developing countries. Although some observational studies have suggested that male circumcision might reduce the incidence of both HSV-2 and HPV, the results have been mixed.

To take a closer look at the issue, an international research team examined data and samples that had already been collected for 2 earlier studies of male circumcision and HIV in Uganda. These earlier trials showed that adult circumcision can reduce a man's risk of acquiring HIV infection through heterosexual intercourse by more than half.

In the new research, funded in part by NIH's National Institute of Allergy and Infectious Diseases (NIAID), the scientists looked at data from 3,393 uncircumcised men, ages 15-49, who had tested negative for HIV and HSV-2 when they first enrolled in the studies. About half the men were randomly assigned to receive medically supervised circumcision at the start of the study. The other half, the control group, was circumcised about 2 years later, at the end of the evaluation period.

The men were assessed at 6, 12 and 24 months for HSV-2 and syphilis infection. In addition, a subgroup of nearly 700 was evaluated for HPV infection at enrollment and at 24 months. The results were reported in the March 26, 2009, issue of the New England Journal of Medicine.

The researchers found that 7.8% of the men circumcised at the start of the study had developed HSV-2 infection by the end of 2 years, compared to 10.3% of the men in the control group.

Circumcision also reduced the prevalence of high-risk HPV infections that are associated with certain cancers. At the end of 2 years, the researchers detected the high-risk HPV strains in 42 of 233 men (18%) circumcised at the start of the study, but in 80 of 287 men (28%) in the control group. Circumcision did not have a significant impact on the incidence of syphilis.

“This new research confirms the substantial health benefits of male circumcision, including reduced acquisition of HIV, genital herpes, HPV and genital ulcer disease,” says NIAID's Dr. Thomas C. Quinn, a co-author of the study.

While adult male circumcision can reduce the risk of becoming infected with HIV, HPV and HSV-2, the strategy is far from completely effective. Therefore, the authors note, safe sex practices, including consistent condom use, are still necessary to get the best protection.

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