Background and objectives: Human papillomavirus is the major etiologic agent of cervical cancer. Although the incidence of cancer of the cervix is high in Jamaica, the prevalence of human papillomavirus among Jamaican women has not been defined.
Goal of the study: To estimate the prevalence of human papillomavirus infection and associated risk factors in women attending an STD clinic in Kingston, Jamaica.
Study design: A cross-sectional survey was done of 202 women attending an STD clinic in Kingston in 1990. Cervical and vaginal cells were collected by lavage, and human papillomavirus genomes were detected in extracted DNA using low-stringency Southern blot hybridization.
Results: Fifty-eight (28.7%) women were identified as HPV positive. Prevalence of HPV by age group was 39% in women 15-19 years old, 33% of women 20-24 years old, 31% in women 25-29 years old, and 17% in those 30 years or older. Increasing age was significantly associated with a lower prevalence of human papillomavirus infection (test for trend, P = 0.025). The effect of age was independent of years of sexual activity. Women reporting more than one sexual partner per month on average were found to have a significantly higher HPV prevalence (odds ratio 2.87, 95% confidence Interval 1.29-6.38), as were women who reported more frequent sex (test for trend, P = 0.006).
Conclusions: Sexual behavior is associated with risk of human papillomavirus infection. The decrease of human papillomavirus prevalence in older women agrees with other studies that argue in favor of a biological effect, such as increased immunity to human papillomavirus with age. A better understanding of why immunity to human papillomavirus may develop in older women may provide the basis for developing an effective vaccine to prevent cancer of the cervix.
PIP: During November 1990-January 1991, DNA was extracted from cervicovaginal cells from 202 women attending the Comprehensive Health Centre, a sexually transmitted disease (STD) clinic, in Kingston, Jamaica, to determine the prevalence of human papilloma virus (HPV). Health workers interviewed these women so researchers could identify risk factors for HPV. 58 women (28.7%) tested positive for HPV. 62% had uncharacterized HPV DNA types. 16% had more than one type of HPV. HPV prevalence fell with age (39% for 15-19 year olds, 33% for 20-24 year olds, 31% for 25-29 year olds and 17% for 30+ year olds; odds ratio [OR] for oldest group = 0.34; p = 0.025), suggesting that older women have developed an immunity to HPV infection. The higher the number of years of sexual activity, the lower the HPV prevalence (40% for 1-4 years, 32% for 5-9 years, and 23% for 10+ years; OR for 10+ years was 0.44; p = 0.03). Women with at least two sexual partners over the last 12 months had a higher HPV prevalence than those with fewer sexual partners (OR = 2.87; p = 0.01). The greater the average number of times women claimed to have had vaginal intercourse per month in the last year, the greater the HPV prevalence (OR for 3-4 times = 2.07, OR for 5+ times = 3.22; p = 0.006). A multiple logistic regression analysis revealed that age confounded the inverse association between HPV prevalence and years of sexual activity. 3% of Pap smears exhibited cervical dysplasia. Further studies are needed to obtain a better understanding of why immunity to HPV may occur in older women. This information could form the basis for developing an effective vaccine against cervical cancer.