Prevalence of human papillomavirus in oral rinse samples from healthy individuals in northern Thailand.

ABSTRACT

BACKGROUND: The incidence of oral cancers associated with human papillomavirus (HPV) has been increasing in recent years. Therefore, it is necessary to elucidate HPV prevalence in oral cells and exposure to risk factors in various age groups. METHODS: Oral rinse samples from healthy individuals in northern Thailand were investigated for HPV prevalence and genotyped using the polymerase chain reaction (GP5+/6+ primers) and DNA sequencing of the PCR products. RESULTS: Samples were collected from 594 participants between 4 and 60 years of age. HPV was detected in 3.7% of samples. The prevalence of HPV-positive cases was 8.6% in the 31-50 age group. HPV prevalence increased with age and was the highest (9.2%) in the 41-50 age group, but decreased (to 3%) in the 51-60 age group. Risk factors significantly associated with HPV-positive cases included alcohol consumption, coffee drinking, sexual activity, and having children. HPV 16 and 18 were common genotypes, especially in the 31-50 age group, and were associated with having sexual activity (odds ratio 19.0 [95% CI 2.5-142.5]). At follow-up of some individuals in the 4-10 age group, a 9-year-old child was found to be positive for HPV18. CONCLUSIONS: These results suggest that HPV can be acquired at a young age and the prevalence peaks in the middle age class among healthy individuals in northern Thailand, especially in the 31-50 age group.