School of Public Health

Tsung-chieh Fu

Human Papillomavirus Infections among Mid-Adult Women

This study describes the short-term natural history of vaginal human papillomavirus (HPV) and the epidemiology of oral and fingernail HPV among mid-adult women. From 2011-2012, 409 30-50 year-old women were recruited and followed for 6 months. Women completed surveys on health and behaviors and provided self-collected vaginal samples (monthly) and oral/fingernail specimens (enrollment and exit) for type-specific PCR-based HPV DNA testing. HPV-positive vaginal samples were tested for viral load. Enrollment blood specimens were tested for type-specific HPV antibodies. In chapter 1, we describe the relationship between host and viral factors and repeat high-risk (HR) HPV detection. HPV viral load (adjusted [a]RR per one log10 increase in viral load=1.10; 95%CI:1.05,1.16) and current smoking (aRR=1.24; 95%CI:0.96, 1.59) were each positively associated with the proportion of type-specific HR HPV detections over follow-up, whereas incident (versus prevalent) detection status (aRR=0.28; 95%CI:0.20, 0.39) and history of pregnancy (aRR=0.83; 95%CI:0.68, 1.0) were negatively associated. Risk factors were similar to those previously identified for long-term persistence, suggesting that short-term persistence may relate to long-term persistence. In chapter 2, we describe the incidence of, and risk factors for, newly detected type-specific HR HPV stratified by type-specific HPV serostatus. Six-month cumulative incidence of HR HPV was higher when there was serologic evidence of prior infection with the same type (2.6%) than when there was not (1.3%). Recent sexual behaviors were associated with incident HPV detection among women without serologic evidence of prior infection only, suggesting that incident detection is more likely due to reactivation or intermittent detection of persisting infection when serologic evidence of prior infection is present. In chapter 3, we evaluated the frequency of, and risk factors for oral and fingernail HPV. Prevalence of genital HPV types detected in the oral cavity (2.5%) and fingernails (3.8%) were low. Concurrent vaginal infection with the same HPV type was strongly associated with both oral (OR=10.29; 95%CI:3.34, 31.72) and fingernail (OR=104.33; 95%CI:30.44, 357.5) HPV detection. Results suggest that DNA deposition between anatomic sites is plausible, though oral and fingernail HPV detection may be unlikely to serve a key role in genital HPV transmission.