Background: No studies have examined human papillomavirus (HPV) infections among couples early in their sexual relationships when transmission is most likely. Our objective was to describe the distribution of HPV infections among recently formed couples, using the partnership as the unit of analysis.
Methods: Women aged 18–24 years attending a university or junior college in Montreal enrolled in a longitudinal study with their new male partners. Self-collected vaginal swabs and clinician-collected swabs from the penis and scrotum were tested for 36 HPV genotypes. Participants self-reported sexual behavior in computerized questionnaires. We analyzed patterns of genital HPV infection in 263 couples using data obtained at enrollment.
Results: Couples had engaged in vaginal sex for a median of 3.9 months. HPV was detected in 64% (169/263) of couples. In 41% (109/263), both partners harbored the same HPV type—nearly 4 times more than expected if HPV status of partners were uncorrelated. There were 583 type-specific HPV infections among 169 couples for whom at least one partner was infected. Of these, 42% were of the same type for both partners (95% confidence interval = 36%–47%). This rose from 25% among those engaging in vaginal sex for less than 2 months to 68% among those at 5 to 6 months.
Conclusions: Although HPV is common, detection of the same type in persons initiating a sex relationship would be rare given type-specific prevalence rates. The high degree of concordance we found suggests a high probability of transmission.
From the aDivision of Cancer Epidemiology, McGill University, Montréal, QC, Canada; Departments of bEpidemiology, Biostatistics and Occupational Health and cFamily Medicine, McGill University, Montréal, QC, Canada; and dDépartement de Microbiologie et Infectiologie, Centre Hospitalier de l'Université de Montréal and Département de Microbiologie et Immunologie, Université de Montréal, Montreal, QC, Canada.
Submitted 23 March 2009; accepted 4 September 2009; posted 10 November 2009.
The HITCH study is funded by the Canadian Institutes for Health Research (operating grant 68893 and team grant 83320). Supplementary and unconditional funding support was provided by Merck-Frosst Canada Ltd and Merck & Co. Ltd. Supported by a research studentship from the Canadian Cancer Society Research Institute and by a Richard H. Tomlinson doctoral fellowship to McGill University (to A.N.B.).
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Correspondence: Eduardo L. Franco, Division of Cancer Epidemiology, Department of Oncology, McGill University, 546 Pine Ave West, Montréal, QC, Canada H2W1S6. E-mail: firstname.lastname@example.org.