Human papillomavirus types 6 and 11 seropositivity: risk factors and association with ano-genital warts among homosexual men.

OBJECTIVES

Human papillomavirus (HPV) types 6 and 11 are most commonly associated with ano-genital warts. There are few data on the sero-epidemiology of HPV6 and HPV11 among homosexual men.

METHODS

Behavioural data and sera for antibodies to HPV6 and HPV11 capsid protein L1 were collected annually for 1427 HIV negative and 245 HIV positive homosexual men. For HIV negative men, a combined variable, HPV6/11, was created (HPV 6 and/or 11) to analyse predictors of seroprevalence and seroincidence.

RESULTS

High rates of HPV6 and HPV11 seroprevalence were found (39.2-53.2% of men). For HPV6/11 (HIV negative men only), seroprevalence was associated with higher numbers of sexual partners, longer history of sexual activity and seropositivity for several sexually transmissible infections. Each year, 12.6% of men younger than 25 years seroconverted. Seroincidence (5.9/100PY) was associated with younger age, more recent male sexual partners, receptive anal fingering and anal chlamydia. Seropositivity and seroconversion were strongly associated with past and incident anal warts.

CONCLUSIONS

HPV6 and HPV11 seropositivity were common among homosexual men. Among HIV negative men, HPV6/11 seroprevalence and seroincidence correlated closely with markers of sexual activity. The high numbers of young men seroconverting each year suggests a role for prophylactic vaccination of young gay men.

SUMMARY: Ano-genital warts, caused by human papillomavirus, are very common. In a community cohort of Australian homosexual men, HPV6 and 11 seroprevalence and seroincidence were high and were associated with past and incident anal warts and other markers of sexual activity.