The results of a study of men in Kenya suggest that infection with human papillomavirus (HPV) can raise the risk of contracting HIV.

The findings are part of a larger clinical trial that, together with two others, showed male circumcision reduces a man's risk of acquiring HIV through heterosexual sex. Other studies of the men have found that circumcision also may lower the odds of HPV infection.

The subjects of the current study were 2,168 uncircumcised, HIV-negative, sexually active Kenyan men ages 18-24. At baseline, 1,089 (50 percent) tested positive for HPV DNA. At 42 months, 5.8 percent of the men with HPV had become HIV-positive, compared to 3.7 percent of the men without HPV.

After controlling for numerous factors -- subsequent circumcision, baseline herpes simplex virus type 2 serostatus, and sexual and demographic risk factors -- the HPV-infected men were still 80 percent more likely to acquire HIV than the men without HPV.

"If our results are confirmed by others, they would suggest that, in addition to male circumcision, vaccinating against HPV could be an effective way to prevent HIV infection," the authors wrote in their discussion. "Two prophylactic HPV vaccines have the potential to prevent invasive cervical cancer and precancerous disease attributable to oncogenic types HPV-16 and HPV-18. The quadrivalent vaccine can also prevent low-risk HPV-6 and HPV-11, which cause genital warts.

"[Hazard ratio] estimates from our analysis suggest that prophylactic vaccines that provide protection against the oncogenic types HPV-16 and HPV-18 may reduce the hazard of HIV infection by half, assuming that vaccination prevents infections with HPV-16 or HPV-18 when administered to young men before first sexual intercourse.

"In uncircumcised men, HPV vaccination and circumcision could lead to even greater reductions: for instance, in our study the estimated 24-month cumulative incidence of HIV infection among uncircumcised men infected with HPV-16 or HPV-18 was 3.9 percent (95 percent CI [confidence interval] 0.5-7.2 percent), compared with only 0.8 percent (95 percent CI, 0.2-1.4 percent) among circumcised men without HPV-16 and HPV-18 infection.

"Although community-based randomized controlled trials have investigated the effect of the prevention of bacterial sexually transmitted infections on the incidence of HIV infection, no trials have examined the effectiveness of preventing HPV infection. Our results warrant the conduct of a randomized controlled trial to determine whether prophylactic HPV vaccination reduces the acquisition of HIV infection," the authors concluded.

The full study, "Increased Risk of HIV Acquisition Among Kenyan Men with Human Papillomavirus Infection," was published in the Journal of Infectious Diseases (2010;201(11):1677-1685).