High prevalence of cervical cancer-associated HPV strains in HIV-positive women in Uganda

Almost 50% of HIV-positive women in Rakai, Uganda are infected with strains of human papilloma virus (HPV) that are associated with a risk of cervical cancer, according to a study published in the online edition of Sexually Transmitted Infections. The study also showed that women who reported symptoms of tuberculosis, shingles or oral thrush, all of which are associated with HIV, had an increased risk of infection with potentially cancer-causing HPV strains.

Fifteen different types of HPV are associated with a risk of cervical cancer. PAP smear screening programmes and the treatment of pre-cancerous lesions have lead to a marked reduction in the incidence of cervical cancer in industrialised countries such as the UK. About 80% of cases of cervical cancer now occur in resource-limited settings.

A number of factors contribute to the higher prevalence of cervical cancer in such countries, including limited access to screening and therapy for precancerous lesions, and the low acceptability of pelvic examinations. The high prevalence of HIV infection in many resource-limited countries, particularly those in southern Africa, is also a likely factor.

Investigators involved in the large Rakai community cohort study have previously demonstrated that the self-collection of vaginal swabs for HPV analysis is feasible and that there is a high degree of concordance between the HPV typing of these swabs and those collected by physicians. Researchers now wished to establish the factors associated with the presence of potentially cancer-causing HPV strains in self-collected vaginal swabs.

The study sample involved 926 women who provided three consecutive swabs. Analysis of these swabs showed that 19% of women had potentially cancer-causing HPV strains present in their vaginas. But the prevalence of these strains was significantly higher in HIV-positive women (47%) than HIV-negative women (15%, p < 0.001).

“Multivariate” analysis showed that HIV was independently associated with the presence of potentially cancer-causing HPV strains (adjusted odds ratio [AOR] = 4.91; 95% CI. 3.14 – 7.66). Younger age was also a significant risk factor, as was having two or more sexual partners in the previous twelve months (AOR = 2.51; 95% CI, 1.26 – 4.99). Individuals who reported tuberculosis, shingles or oral thrush were also significantly more likely to be infected with high-risk HPV strains (AOR = 4.52; 95% CI, 1.01 – 20.21).

“These findings have important implications for future studies in settings where resource constraints limit pelvic exams, and most importantly, where women may be reluctant to participate in studies that rely on pelvic exams for data collection”, write the investigators.

“HIV status, herpes zoster, oral candidiasis, or TB infection were associated with carcinogenic HPV, consistent with other studies which found HIV, and HIV-associated immunosuppression to be independently associated with HPV positivity”, continue the investigators. They suggest, “among HIV-positives, it is possible that immune suppression leads to reactivation of these latent… infections as well as reducing HPV clearance.”