Soil-transmitted helminth infection increases risk for HPV
The increased prevalence of HPV at older ages in Latin America was partially linked to an immunological deficiency caused by soil-transmitted helminth infections in women from endemic regions, according to recent findings.
“Our observation of a significant [T helper type 2 (Th2)]-polarized immune signature … in cervical secretions of the STH-infected, but not STH-uninfected women, strongly supports [the] hypothesis,” the researchers wrote.
Researchers compared HPV prevalence among 192 women from a nonendemic region (Lima) with 190 women from an endemic helminth parasite region (Iquitos) in Peru. Stool samples were collected from the participants and tested for soil-transmitted helminth (STH) infections. Spearman’s rank correlation with Sidak correction was used to compare soluble immune marker profiles in STH-infected vs. uninfected women.
Ninety women (84.8%) from the endemic region were infected with one of the four STHs, including Ascaris lumbricoides (59%), Trichuris trichiura (10%), hookworm (3.8%) and Strongyloides stercoralis (1%). No STHs were reported in the nonendemic region.
The investigators said there was a 60% greater prevalence of HPV in the endemic vs. nonendemic region. Women infected with STHs were nearly twice as likely to develop HPV compared with uninfected women (prevalence ratio =1.6; 95% CI, 1-2.6). The presence of other parasitic infections, however, did not increase the risk for HPV.
The findings, if confirmed, could have significant implications for worldwide cancer control, the researchers wrote.
“Elaboration of these pilot results, including direct assessment of whether STH-treatment restores immune balance at the cervix and induces immunologic control of HPV infection, will be critical for proof–of-concept that current WHO strategies to reduce the global impact of neglected tropical diseases will have broad-ranging effects on adult chronic diseases such as HPV-associated cancers, as well as the developmental morbidities more commonly associated with childhood helminth infection,” the researchers wrote. – by Jen Byrne
Disclosure: One of the researchers reports being an employee and shareholder of Merck, the maker of Gardasil.