Introduction. Oncogenic human papillomaviruses (HPVs) are the central causal agent of cervical cancer. Vaccines were developed, and are currently being tested in phase II/III trials. The host immune response is type-specific, and likely not all oncogenic types will be targeted by vaccine formulations. A theoretical concern is that infection with less prevalent oncogenic HPV types may replace the disease prevented by a vaccine against the most common oncogenic HPVs. This underscores the importance of having a better understanding of the epidemiology of infections with multiple HPV types, in terms of their dynamics and risk factors. The objectives of this project were to: (1) describe the occurrence of HPV coinfections; (2) determine whether prior HPV infections are associated with acquisition and clearance of other HPV types, and; (3) identify predictors of HPV coinfection. / Methodology. In a prospective cohort of 2075 Brazilian women, cervical specimens were collected for cytology and HPV DNA detection. Information on potential risk factors was obtained by interview at baseline, and at return visits. Follow-up visits were scheduled every 4 months in the first year and every 6 months thereafter. / Results. The prevalence of HPV coinfection was 7.6% among all women, and 21% among HPV-positive women. HPV coinfection was less common among cytologically normal women, and peaked among women with lower grade cytological abnormalities. Both prevalence and incidence of HPV coinfection decreased markedly with increasing age. HPV infection at enrolment was associated with a higher risk of infection with any other HPV type. The adjusted hazard ratios and 95% confidence intervals (95% CI) of acquisition of any HPV type were: 2.2 (95% CI: 1.5--3.2) for oncogenic types excluding HPV 16 and 18 detected at enrolment, and 2.6 (95% CI: 1.7--4.2) for HPV 16 or 18 detected at enrolment. Predictors of HPV coinfection included younger age, higher number of sexual partners, a history of condyloma, and younger age at first sexual intercourse. / Conclusion. HPV coinfections were relatively common, especially among younger women. Prior HPV infections increased the risk of subsequent infections with other types. These results may have implications for vaccine development and public health decisions about vaccination programs.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.84429 |
| Date | January 2003 |
| Creators | Rousseau, Marie-Claude, 1969- |
| Contributors | Franco, Eduardo L. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Epidemiology and Biostatistics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001975771, proquestno: AAINQ88573, Theses scanned by UMI/ProQuest. |
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