Understanding the association between immune-modulating helminths and HPV or cervical cancer: A scoping review

Background: Cervical cancer disproportionately affects people living in low- and middle-income countries (LMICs). While access to effective preventive interventions explains some of the disparity, biological causes cannot be ruled out as important contributors to the observed disparities in cervical cancer outcomes. Since chronic infection with helminths which cause immune dysregulation and suppress anti-viral responses is common in LMICs, we sought to review the available epidemiologic evidence evaluating associations between helminth infection and HPV infection and/or cervical cancer. Methods: We searched five databases of scientific publications using search terms targeted towards journal articles published between 1990–2022 evaluating an epidemiologic association between helminth infection and HPV prevalence, persistence, or cervical cancer progression. Out of 93 reports assessed for eligibility, we identified eight relevant studies and describe them in this scoping review. Results: All eight studies suggest a possible positive association between helminth infection and HPV or cervical cancer. Six studies found a positive trend in association between schistosomiasis and cervical neoplasia; two studies between hookworm infection and HPV prevalence; and 1 study between Ascaris, Trichuris, and Strongyloides and HPV prevalence. Conclusions: Published evidence suggests positive trends towards an association between helminth infection and cervical neoplasia. Given the high burden of helminth and HPV co-infection in LMICs, further evaluation of the association between helminth infection and HPV or cervical cancer is warranted. Author summary: The high prevalence of helminth and HPV co-infections in LMICs significantly impacts quality of life, necessitating studies to expand our knowledge of their epidemiological and health impacts. Understanding the interaction between helminth infection, persistence of high-risk HPV, and cervical cancer is then crucial for developing evidence-based public health programs to improve health outcomes in affected populations. Chronic helminth infections, such as schistosomiasis and hookworm, induce immune responses that can impair antiviral responses critical for HPV clearance. Eight studies included in this scoping review suggest a positive association between helminth infection and cervical pre-cancerous and cancerous lesions, warranting further evaluation of this interaction given the high burden of co-infection. Findings expand the evidence-base to support the need to incorporate schistosomiasis screening into gynecological examinations and/or cervical cancer screening efforts to enhance the accuracy of diagnosing and treating pre- and cancerous cervical lesions in endemic regions.