Schistosomiasis in Malawi: A systematic review

Abstract

Introduction: Schistosomiasis remains an important public health problem that undermines social and economi development in tropical regions of the world, mainly Sub-Saharan Africa. We are not aware of any systematic revie of the literature of the epidemiology and transmission of schistosomiasis in Malawi since 1985. Therefore, w reviewed the current state of knowledge of schistosomiasis epidemiology and transmission in this country an identified knowledge gaps and relevant areas for future research and research governance Methods: We conducted computer-Aided literature searches of Medline, SCOPUS and Google Scholar using th keywords: "schistosomiasis", "Bilharzia", "Bulinus" and "Biomphalaria" in combination with "Malawi". These searche were supplemented by iterative reviews of reference lists for relevant publications in peer reviewed internationa scientific journals or other media. The recovered documents were reviewed for their year of publication, location o field or laboratory work, authorship characteristics, ethics review, funding sources as well as their findings regardin parasite and intermediate host species, environmental aspects, geographical distribution, seasonality of transmission and infection prevalence and intensities Review: A total of 89 documents satisfied the inclusion criteria and were reviewed. Of these, 76 were published i international scientific journals, 68 were peer reviewed and 54 were original research studies. Most of the document addressed urinary schistosomiasis and about two thirds of them dealt with the definitive host. Few document addressed the parasites and the intermediate hosts. While urinary schistosomiasis occurs in most parts of Malawi intestinal schistosomiasis mainly occurs in the central and southern highlands, Likoma Island and Lower Shire. Studie in selected communities estimated prevalence rates of up to 94.9% for Schistosoma haematobium and up to 67.0% fo Schistosoma mansoni with considerable geographical variation. The main intermediate host species are Bulinus globosu and Bulinus nyassanus for urinary schistosomiasis and Biomphalaria pfeifferi for intestinal schistosomiasis. Seasonality o transmission tends to vary according to geographical, environmental, biological and behavioural factors Conclusion: Transmission of schistosomiasis in Malawi appears to be highly focal, with considerable variation in spac and time. Many locations have not been covered by epidemiological investigations and, thus, information on th transmission of schistosomiasis in Malawi remains fragmented. Functional infection risk assessment systems based o systematic investigations and surveillance are required for developing informed prevention and control strategies.