Authors

Discussion

Waterborne diseases pose a significant health risk in many lower-middle-income countries in tropical and sub-tropical regions of the world. One disease is schistosomiasis, caused by blood flukes of the Schistosoma genus, chiefly Schistosoma mansoni and Schistosoma haematobium in sub-Saharan Africa. Schistosoma mansoni causes intestinal schistosomiasis whereas S. haematobium causes urogenital schistosomiasis with co-infections also possible. Additionally, urogenital schistosomiasis is associated with increased transmission of HIV in both genders. Since the schistosome lifecycle has two free-living larval stages alongside those that develop inside freshwater snails, these parasites are particularly sensitive to environmental change. In coming years climate change is expected to drive locally altered temperatures and precipitation around aquatic habitats where schistosomes exist. This will (in)directly impact both upon human populations and associated agricultural practices. In this poster, we review the contemporary literature to ascertain how climate change will affect the putative distribution of schistosomiasis in East Africa, speculating on either increases or decreases in infection risk. Google Scholar was primarily used, search terms included variations of “Climate Change”, “Schistosomiasis”, “Schistoso*”, “Africa”, “East Africa”, “Biomphalaria”, “Bulinus” and “Waterborne Disease”. The Web of Science search tool was also used for obtaining sources. Examples of search terms include “Waterborne Disease AND Climate Change”. It appears that many environmental water bodies are already towards their upper thermal thresholds for intra-molluscan development and survival of infective cercariae. In future, these waterbodies will become unsuitable for harbouring schistosomes. Nonetheless snail populations are set to increase with rising temperatures although competition with non-intermediate snails may become greater. Expected increases in precipitation in wetter areas of East Africa may lead to the creation of new suitable habitats for infection, albeit ephemeral through time. Increased precipitation can lead to chaotic flooding and environmental denudation events that expand the risk of people coming into contact with potentially infectious freshwater sources. By contrast in currently water stressed and drier areas of East Africa, annual precipitation may further decrease which may cause people and livestock to coalesce further to where spatial areas standing water is more available. Agriculture changes may therefore concentrate infection risk where more farming and fishing is needed to sustain expanding populations. The latter includes a growing agricultural workforce tied to freshwater habitats, for example, those associated in rice fields. With the detection of hybrid schistosomes with zoonotic potential, future control of human schistosomiasis will need a OneHealth approach. We therefore surmise there will be a general increase in schistosomiasis with associated climate change but given the focal nature of transmission at local levels greater on-the-ground surveillance with precision mapping is needed to better validate predictions of broader climate change in East Africa.