Background: Relatively little is known about the epidemiology of anal human papillomavirus (HPV) infection in healthy women and its association with cervical HPV infection.
Methods: he association of an incident cervical (or anal) HPV infection with the subsequent risk of a genotype-concordant incident anal (or cervical) HPV infection was examined in a longitudinal cohort study of 751 sexually active women. Age-adjusted hazard ratios, obtained using Cox regression, served as measurements of relative risk (RR).
Results: Among women, the RR of acquiring an anal HPV infection after a cervical infection with HPV of the same genotype was 20.5 (95% confidence interval, 16.3-25.7), and the RR of acquiring a cervical HPV infection after an anal infection with HPV of the same genotype was 8.8 (95% confidence interval, 6.4-12.2), compared with women without a previous anal/cervical infection with HPV of a concordant genotype. RRs varied by phylogenetic species, with HPV alpha3/alpha15 and alpha1/alpha8/alpha10 types having a greater likelihood than other types of HPV infecting the anus among women with a previous infection at the cervix with HPV of the same genotype.
Conclusions: It appears common for anal and cervical HPV infections to occur consecutively. The high degree of genotype-specific concordance suggests that the cervix (vagina) and anus may serve as reservoirs for HPV infection at the other anatomical site.