AbstractsBiology & Animal Science

Human papillomavirus (HPV) infection is recognized as a necessary cause of cervical cancer. While most HPV infections are asymptomatic and naturally cleared by the immune system, some infections that are not cleared can become persistent, increasing the risk of developing pre-invasive cervical lesions. Worldwide, cervical cancer is the second most common cancer in women with an estimated half million new cases and one quarter million deaths occurring each year. While HPV is a necessary cause of cervical cancer, it is not sufficient and little remains known about the factors that can influence the natural history of HPV infection. Established co-factors of cervical cancer include tobacco smoking, parity, co-infection with HIV and prolonged oral contraceptive use. However, there remains limited information about the characteristics that promote incidence and persistence of HPV infection with respect to genital health/hygiene and local inflammation of the cervix. The Ludwig-McGill cohort study is one of the largest cohort studies looking at the natural history of HPV infection and risk of cervical precancer. Beginning in 1993, 2462 women were recruited from low-income neighbourhoods of São Paulo. Data were collected by nurse-administered questionnaires on recent gynecologic symptoms and treatments, as well as contraceptive methods used. Outcomes were assessed by Pap cytology and molecular HPV DNA testing on cervical specimens collected every four months in the first year and every six months thereafter. Using questionnaire and laboratory data from this study and a one-year period prevalence model, we examined the effects of reproductive and vaginal health on HPV infection. In addition, cytopathology reports from all Pap smears collected were used to obtain additional information on cervical inflammation and relate those to the risk of HPV infection. Significant associations were then stratified to determine if any potential confounding factors played a role. For contraceptive methods, our results indicate that condom use and contraceptive injections were associated with and increased risk of HPV infections. In addition, we found a slightly protective role for intrauterine devices and tubal sterilization in risk of HPV infection. However, several of these associations can be explained upon stratification of behavioral factors such as marital status and lifetime number of partners. Certain hygiene factors such as tampon use and previous bacterial or fungal infections were also found to be associated with an increased risk of HPV infection. Lastly, using the cytopathology reports, it appears that local inflammation of the cervix is also associated with increased risk of HPV infection. The results of this research attempt to assist gynecologists in determining risk of HPV infection based on information from patients and laboratory findings available at a patient's visit. Given that there is limited research available on the role of genital hygiene, reproductive health and inflammation on the natural history of HPV…