Multidisciplinary studies of schistosomiasis and HIV on the shoreline of Lake Malawi: A longitudinal cohort study of male genital schistosomiasis (MGS) among fishermen in Mangochi District.

Abstract

Male genital schistosomiasis (MGS) is a specific chronic manifestation of schistosomiasis associated with schistosome eggs and related pathologies in the genital system of men inhabiting or visiting endemic areas. Despite description of the first recognised MGS patient by Madden in 1911, the epidemiology, diagnostic testing and case management of MGS are not well described owing to limited research and diminishing focus over several decades. Furthermore, as the human immunodeficiency virus (HIV) epidemic expands across sub-Saharan Africa (SSA), there is renewed interest in MGS owing to plausible but as of yet under-explored interactions with HIV. To shed new light on MGS, a longitudinal cohort study was conducted among fishermen along the southern shoreline of Lake Malawi, an endemic area in SSA to investigate the prevalence of MGS, its associated knowledge, attitudes and practices (KAP), and determine the potential increase of viral shedding in semen of HIV-positive men with MGS. A systematic review conducted prior to the onset of the research fieldwork describing the MGS epidemiology, clinico-pathological manifestations, diagnostic techniques and treatment outlined and informed the current approach to the body of research presented here. Fishermen aged 18+ years were recruited into the study after providing informed written consent and individual questionnaires were administered to assess their KAP associated with MGS. Thereafter, participants submitted urine, semen, and blood for point-of-care (POC) field parasitological tests, and later laboratory-based molecular polymerase chain reaction (PCR), and HIV VL analyses. In addition, transabdominal and scrotal ultrasonography to assess the pathological effects of MGS on their genital organs were performed. Praziquantel therapy was provided to all participants, together with the follow-up diagnoses and treatment dates after 1, 3, 6 and 12-months’ intervals. 376 fishermen (320 HIV-negative and 56 HIV-positive on Antiretroviral therapy (ART)) aged between 18 and 70 years (median: 30.0 years), were recruited into the study, and had questionnaires interviews. At baseline, prevalence of UGS (S. haematobium eggs in urine) was 17.1% (n = 210, median: 2.3 per 10 ml, range: 0.1 – 186.0), 3.8% had a positive point-of-care circulating cathodic antigen (POC-CCA) indicative of intestinal S. mansoni infection, while MGS prevalence was 10.4% by semen microscopy (n = 114, median: 5.0, range: 0.1 – 30.0) and 26.5% by real-time PCR (n = 65, Ct value range: 18.8 – 36.6). More participants (66.7%) with schistosome eggs in semen were observed to not have any eggs in their urine. 6.9% of participants (n = 130) were observed to have pathological lesions in their genital organs on ultrasonography. For 15 HIV-MGS cases and 16 HIV-only controls who submitted paired blood and semen samples during the longitudinal study, more cases than controls had detectable and quantifiable VL, which regressed with PZQ. Similarly, the results of the diagnostic tests improved, with negative schistosome egg, real-time PCR in semen and pathological resolution on follow-up. In conclusion, MGS has been observed, via parasitological, molecular and radiological examinations, to be common in local male inhabitants (fishermen) of endemic areas along the south shoreline of Lake Malawi in the SSA region and shown to respond to standard PZQ treatment. Improving availability and accessibility for all people in these areas to PZQ, diagnostic tools for MGS, and combined HIV and schistosomiasis control interventions are advocated to reduce morbidity and improve the lives and reproductive health of men, their partners and communities in endemic areas.