No abstract

An inverse relationship between age and human papillomavirus (HPV) prevalence has been reported in many developed countries, but information on this relationship is scarce in many other parts of the world. We carried out a cross-sectional study of sexually active women from the general population of 15 areas in 4 continents. Similar standardised protocols for women's enrolment, cervical specimen collection and PCR-based assays for HPV testing were used. HPV prevalence in different age groups was compared by study area. 18,498 women aged 15-74 years were included. Age-standardised HPV prevalence varied more than 10-fold between populations, as did the shape of age-specific curves. HPV prevalence peaked below age 25 or 35, and declined with age in Italy, the Netherlands, Spain, Argentina, Korea and in Lampang, Thailand and Ho Chi Minh, Vietnam. This was not the case in Songkla, Thailand nor Hanoi, Vietnam, where HPV prevalence was low in all age groups. In Chile, Colombia and Mexico, a second peak of HPV prevalence was detected among older women. In the poorest study areas in Asia (Shanxi, China and Dindigul, India), and in Nigeria, HPV prevalence was high across all age groups. The substantial differences observed in age-specific curves of HPV prevalence between populations may have a variety of explanations. These differences, however, underline that great caution should be used in inferring the natural history of HPV from age-specific prevalences. ' 2006 Wiley-Liss, Inc.

Data on the incidence and determinants of human papillomavirus (HPV) infection in women >30 years old are scarce. To address this, a cohort of 1610 women--15-85 years old, HPV negative, and with normal cytological results at baseline--was monitored every 6 months for an average of 4.1 years. Information on risk factors and cervical samples for cytological testing and detection and typing of HPV DNA were obtained at each visit. The incidence of high-risk types was higher than that of low-risk types (5.0 vs. 2.0 cases/100 woman-years). The age-specific incidence curve for high-risk types was bimodal, whereas the incidence of low-risk types gradually decreased with age. Infections with high-risk types lasted longer than infections with low-risk types (14.8 vs. 11.1 months). In this cohort of cytologically normal women, the incidence of cervical HPV infection was high, and the epidemiological profile of high-risk HPV types was different from that of low-risk types.

Human papillomavirus is the principal risk factor associated with cervical cancer, the most common malignancy among women in Colombia. We conducted a survey, aiming to report type specific prevalence and determinants of human papillomavirus infection in women with normal cytology. A total of 1859 women from Bogota, Colombia were interviewed and tested for human papillomavirus using a general primer GP5+/GP6+ mediated PCR -EIA. The overall HPV DNA prevalence was 14.8%; 9% of the women were infected by high risk types, 3.1% by low risk types, 2.3% by both high risk/low risk types and 0.4% by uncharacterized types (human papillomavirus X). Thirty-two different human papillomavirus types were detected, being human papillomavirus 16, 58, 56, 81(CP8304) and 18 the most common types. The human papillomavirus prevalence was 26.1% among women younger than 20 years, 2.3% in women aged 45 -54 years, and 13.2% in women aged 55 years or more. For low risk types the highest peak of prevalence was observed in women aged 55 years or more. Compared to women aged 35 -44 years, women aged less than 20 years had a 10-fold increased risk of having multiple infections. Besides age, there was a positive association between the risk of human papillomavirus infection and number of regular sexual partners and oral contraceptive use. In women aged below 25 years, high educational level and having had casual sexual partners predicted infection risk. In conclusion, there was a broad diversity of human papillomavirus infections with high risk types being the most common types detected. In this population multiplicity of sexual partners and, among young women, high educational level and casual sexual partners seem to determine risk.

Little is known about the factors that influence clearance of human papillomavirus (HPV), the primary cause of cervical carcinoma. A total of 227 women cytologically normal and HPV positive at baseline were identified from a population-based cohort of 1,995 Bogota, Colombia, women aged 13-85 years followed between 1993 and 2000 (mean follow-up, 5.3 years). HPV DNA detection and viral load determination were based on a GP5+/GP6+ polymerase chain reaction enzyme immunoassay. Rate ratio estimates for HPV clearance were calculated by using methods for interval-censored survival time data. Analyses were based on 316 type-specific HPV infections. HPV 16 had a significantly lower clearance rate than infections with low-risk types (rate ratio (RR) = 0.47, 95% confidence interval (CI): 0.32, 0.72), HPV types related to HPV 16 (types 31, 33, 35, 52, 58) had intermediate clearance rates (RR = 0.62, 95% CI: 0.47, 0.94), and other high-risk types did not show evidence of slower clearance compared with low-risk types. Infections with single and multiple HPV types had similar clearance rates. There was no evidence of a dose-response relation between clearance and viral load. Observed was slower clearance in parous women (RR = 0.64, 95% CI: 0.47, 0.89) and faster clearance in ever users of oral contraceptives (RR = 1.38, 95% CI: 1.07, 1.77).