Prevalence, Potential Predictors, and Genotype-Specific Prevalence of Human Papillomavirus Infection among Sexually Active Students in Japan

Abstract

Background and methods: We conducted a community-based study to evaluate genotype-specific prevalence of high-risk HPV (HR-HPV) and potential predictors of its presence in young, asymptomatic, female college students. Self-administered surveys and vaginal swabs for self collection were distributed to students of participating schools. A sufficient cellular component in cervical samples was verified by examining for the presence of human β-globin DNA by PCR. A total of 1,118 valid cervical samples were subjected to screening for HR-HPV infection with the Digene Hybrid Capture 2 assay, followed by identification of HPV genotypes with GENOSEARCH HPV31 kit. Logistic regression was used to adjust for confounding factors associated with HR-HPV positivity and the adjusted odds ratio (AOR) was calculated.

Results: The median age of recruited students was 20 years. Of the 1,118 women who provided valid cervical samples for testing, 770 had sexual intercourse in the past, of which 125 (16.2%) were positive for HR-HPV. Logistic regression analysis revealed that HR-HPV infection was associated with smoking history (AOR 2.13; 95% confidence interval [CI] 1.98 to 5.05; p < 0.01), total number of partners (AOR 4.72; 95% CI 1.97 to 11.32 if > 5 partners; p < 0.001), number of partners in the past 6 months (AOR 3.12; 95% CI 1.42 to 6.87; p < 0.01), improper use of condoms (AOR 2.21; 95% CI 1.25 to 3.90; p < 0.01), and chlamydia infection (AOR 2.61; 95% CI 1.28 to 5.34; p < 0.01). The most common HR-HPV genotype was type 52 (6.4%), followed by 16 (3.1%), 56 (3.0%), and 58 (2.6%).

Conclusion: Compared with previous reports in East Asian coutries, the prevalence of HR-HPV infection among young, asymptomatic, female students before the nationwide use of vaccination in Japan was in the intermediate range. The most common HR-HPV genotypes were HPV 52, 16, 56, and 58.

Fig 1. Prevalence of high-risk HPV by genotype among 770 sexually active subjects.

Using the cervical specimens that participants had collected by themselves, HPV genotypes were analyzed using Hybrid Capture 2 assay (Digene/Qiagen) and GENOSEARCH HPV 31 (Medical & Biological Laboratories, Nagoya, Japan). Numbers on the x-axis indicate genotypes. The number on the top of the column indicates the number of women infected with high-risk HPV of the specific genotype.