Authors

O Lamberti²; R Ndubani³; J Fitzpatrick³; H Kelly²; N Kasese³; E Webb²; B Nyondo³; B Kosloff⁴; M Cheeba³; P Mayaud²; H Ayles²; B Webster¹; K Shanaube³; A Bustinduy²;  ¹ Natural History Museum, UK;  ² London School of Hygiene and Tropical Medicine, UK;  ³ Zambart, Lusaka, Zambia;  ⁴ Longhorn Vaccines and Diagnostics LLC, Bethesda, United States

Discussion

Introduction: Female genital schistosomiasis (FGS) is a chronic gynaecological disease caused by Schistosoma haematobium (Sh) egg-deposition in the female genital tract. FGS is highly prevalent in sub-Saharan Africa (SSA), the region with the highest cervical cancer incidence and mortality globally, due to high-risk (HR-) human papillomavirus (HPV) infections. The interplay of these infections is largely unknown. The ongoing Zipime Weka Schista longitudinal study aims to integrate home-based genital self-sampling for FGS and HR-HPV, and self-testing for HIV and Trichomonas vaginalis (Tv) in two endemic areas in Zambia. Here, we present baseline data from the study and evaluated the association between FGS and HR-HPV prevalence.

Methods: Sexually active women aged 15-50 years were recruited by community health workers at home, where participants completed a questionnaire, provided a urine sample, two cervical cervicovaginal self-swabs, and performed self-tests for HIV and Trichomonas vaginalis (Tv). Participants were then referred to the clinic where a midwife obtained cervicovaginal swabs, cervicovaginal lavage (CVL), and assessed FGS-associated genital lesions using colposcopy (EVA System, MobileODTⓇ). Cervicovaginal swabs were molecularly analysed for HR-HPV detection (Cepheid GeneXpert) and FGS (Schistosoma qPCR). Visual-FGS was defined as the presence of sandy patches, rubbery papules, or abnormal blood vessels. Molecular-FGS was defined as Sh DNA detected on cervicovaginal swab collected either at home or in clinic. Urinary Sh infection was detected by urine microscopy and by urine circulating anodic antigen (CAA).

Results: From January 2022 to June 2023, 2,532 women (median age 28 years [IQR: 22-36]), were enrolled at home and 66.9% (1,694/2,532) attended the clinic visit. Visual-FGS and molecular-FGS prevalence was 13.6% (228/1,681) and 6.5% (165/2,532), respectively. Urinary Sh positivity was 5.2% (132/2,532) by microscopy, and 15.4% (388/2,520) by CAA. Baseline prevalence of HR-HPV was 27.7% (689/2,488), and HIV and Tv were detected in 17.5% (443/2,531) and 10.4% (242/2,326) of participants, respectively. HR-HPV prevalence was significantly higher among women with molecular-FGS compared to those without (35.6% vs. 27.4%, X2 p-value=0.03). No statistically significant difference was observed in the prevalence of HR-HPV infection by visual-FGS status (X2 p-value=0.53). Multivariable logistic regression adjusted for age and marital status revealed that women with molecular-FGS were more likely to be HR-HPV positive compared to those without (adjusted Odds Ratio=2.4, 95%CI 1.0-1.9).

Conclusions: The high prevalences of FGS and HR-HPV in Zambia, and the association between these two infections, informs the possible integration of FGS and cervical cancer screening strategies