Varying effects of global warming on schistosomiasis and intermediate host snails species.
Anna-Sofie Steensgaard
Little is currently known about the exact outcome of climate change effects on schistosomiasis, a disease caused by a snail-borne blood fluke that affects more than 250 million people mainly in tropical and subtropical countries. Many different species of parasites and snail host are involved in the disease transmission, and the effects of warming will vary with each the snail-parasite species’ specific ecologies and the spatio-temporal scale of investigation. A systematic review revealed that there has been a considerable growth in the attention given to the impacts of climate change on schistosomiasis in the peer-reviewed literature over the last two decades, but while there has been considerable growth in schistosomiasis research output related to the human part of the life cycle, the research output related to the intermediate host snail – the most climate sensitive part of the parasite life-cycle – has at best been stagnant. Overall, little consensus about the direction of outcomes currently exist: Studies from the northern and southern range margins for schistosomiasis indicate an increase in transmission as the most likely outcome, whereas contractions or status quo scenarios emerged from the central parts of the disease distribution. The current lack of consensus suggests that climate change is more likely to shift than to expand the geographic ranges of schistosomiasis. A comparison between the current geographical distributions and the thermo-physiological limitations of the main African schistosome species offered additional insights, and showed that they already exist near their thermo-physiological niche boundaries. As such, both species stand to move considerably out of their “thermal comfort zone” in a future, warmer Africa, but their invasive potential appear to be increasing at the northern range margins.
Biography: To be confirmed