About half of men carry human papilloma virus (HPV), a cause of cervical cancer in women and genital warts in both sexes, reported researchers in the March 12 issue of the Lancet. Data came from 1,159 men (average age, 32 years) recruited from Brazil, Mexico, and the United States. Swabs of the penis and genital area detected HPV infections in 50% of the participants when the study started. Over the next 28 months, 1,572 new infections were identified, particularly in men with more than one sex partner. The number of cancer-causing HPV infections was 2.4 times higher in men with a lifetime history of 50 or more female partners than in those with one partner or none. It's worth noting that most HPV strains took longer to clear in younger men (ages 18 to 30), although the clearance time of HPV 16 wasn't age dependent and took the longest to clear of all cancer-causing strains. "The results from this study provide much needed data about the incidence and clearance of HPV infection in men; these data are essential for the development of realistic cost-effectiveness models for male HPV vaccination internationally," the authors write.