The Natural History of Type-specific Human Papillomavirus Infections in Female University Students

Little is known about the average duration of typespecific human papillomavirus (HPV) infections and their patterns of persistence. The objectives of this study were to evaluate the rate of acquisition and clearance of specific HPV types in young women. Female university students (n 621) in Montreal were followed for 24 months at 6-month intervals. At each visit, a cervical specimen was collected. HPV DNA was detected using the MY09/MY11 PCR protocol followed by typing for 27 HPV genotypes by a line blot assay. The Kaplan-Meier technique was used to estimate the cumulative probability of acquiring or clearing a HPV infection considering types individually or in high-risk (HR) or low-risk (LR) groups defined by oncogenic potential. Incidence rates were 14.0 cases/1000 women-months (95% confidence interval, 11.4 –16.3) and 12.4 cases/1000 women-months (95% confidence interval, 10.4 –14.8) for acquiring HR and LR HPV infections, respectively. The 24-month cumulative rates of acquisition were highest for HPV-16 (12%), HPV-51, and HPV-84 (8%). Of the incident infections, HPV-16 was the most persistent (mean duration, 18.3 months), followed by HPV-31 and HPV-53 (14.6 and 14.8 months, respectively). HPV-6 and HPV-84 had the shortest mean duration time (<10 months) The mean durations of incident, same-type LR or HR HPV infections were 13.4 months and 16.3 months, respectively. Whereas the majority of episodes with a type-specific HPV infection cleared within 2 years, there were many women who were either reinfected with a new