The epidemiology of infection with human papillomavirus differs in men compared to women

Men who have sex, the prevalence of human papillomavirus infection is important for all age groups as it peaked around 30 years before declining among women, say the authors of a study published in the "Journal of Infectious Diseases."

Several studies have demonstrated a causal link between HPV infection and cancers of the cervix and anus. Many others have also shown that HPV infection is strongly associated with age, reaching a peak relatively early to decrease after age 30.

Little is known, however, the prevalence in relation to age, anal HPV infection among men who have sex with men. Most work has indeed focused on HIV-positive men, usually belonging to the same age group.

Peter V. Chin-Hong and colleagues at the University of California at San Francisco and describe for the first time in their study of anal HPV infection in a population of men who have sex with men, HIV-negative, ages and varied situations.

The study was conducted between January 2001 and October 2002 among 1,218 gay men aged 18 to 89 years. More than half (57%) of them had anal HPV infection, regardless of age or place of residence.

Among the risk factors associated with infection, the authors note the importance of having more than five partners in the six months preceding the survey.

Nearly half of those infected (45%) had more than one HPV type. The prevalence of infection with the HPV types "high risk" associated with an increased risk of invasive anal cancer was 26%, say the authors.

For the latter, the different epidemiology of HPV infection between men and women may reflect the difference between these two groups in terms of number of new partners after the age of 30. The authors also suggest that specific and hormonal differences in body (anus and uterus) contribute to these epidemiological changes.

So they question "the assumptions made in the past about the possible extrapolation of cervical cancer in women with anal HPV infection in humans" and suggest further work in this area to better determine the impact of this discovery on the development of an HPV vaccine and understanding the risk factors for anal cancer.