Genital Human Papillomavirus Infection: Incidence and Risk Factors in a Cohort of Female University Students
February 27, 2003
Incidence data on human papillomavirus are limited, and risk factors for transmission are largely unknown. The authors of the current study followed 603 female Washington State University students between 1990 and 2000 at four-month intervals. At each visit, a nurse-practitioner administered a face-to-face interview and a standardized pelvic examination and collected separate cervical and vulvovaginal specimens for HPV DNA analysis. A subset of 529 women provided 2,640 toothbrush samples of the buccal mucosa, which were also analyzed for HPV DNA. Participants answered questions about socioeconomic status, gynecologic and obstetric history, current and past sexual behavior, and history of genital tract infections at the first visit. On subsequent visits, this information was updated.Adapted from:
The researchers focused their analyses on the 444 women who were HPV-DNA negative at the time they enrolled in the study. The mean age of the subjects at enrollment was 19.2, and the mean lifetime number of partners of the 296 women who were sexually active was 1.8. One hundred forty-eight participants were virgins at enrollment.
Investigators found that the cumulative 24-month incidence of HPV in women who were sexually active at enrollment was 38.8 percent, compared to 38.9 percent of virgins who initiated sexual activity. The most common types of first infections were HPV-16, -56, and -6. Twenty-one women were infected with multiple types. Incidences calculated from the time of new-partner acquisition were comparable for virgins and nonvirgins.
Smoking, use of oral contraceptives, and reporting a new male sex partner -- especially one known for less than eight months or who had other partners -- were predictive of increased risk of HPV infection. Always using male condoms with a new partner was not protective. The 24-month cumulative incidence of HPV in virgins was 7.9 percent. "Infection in virgins was rare, but any type of nonpenetrative sexual contact was associated with an increased risk," Winer and colleagues wrote. Analysis of oral specimens found no association between incident oral HPV infection and oral-penile contact.
"In conclusion," the researchers summarized, "the present study showed that the incidence of genital HPV associated with acquisition of a new sex partner is high and that risk of infection is especially high if a partner has been known for less than eight months and if a partner reports having had sex with other partners. Oral HPV infection is rare and not clearly associated with oral-penile contact. Genital HPV infection in virginal women seems to be rare, but nonpenetrative sexual contact is a plausible route of transmission."
American Journal of Epidemiology
02.01.03; Vol. 157; No. 3: P. 218-226; Rachel L. Winer; Shu-Kuang Lee; James P. Hughes; Diane E. Adam; Nancy B. Kiviat; Laura A. Koutsky
This article was provided by CDC National Prevention Information Network. It is a part of the publication CDC HIV/Hepatitis/STD/TB Prevention News Update.