Cryptosporidium movement in water: impact of eutrophication and climate change on the zoonotic disease agent

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This project will be the first to follow the fate of Cryptosporidium oocysts as they enter aquatic food chains in Welsh riparian ecosystems. Cryptosporidium is a human pathogen unknown until the mid-1970s; in 1993 0.4 million people were infected in Milwaukee following a water treatment failure, and since then, large outbreaks throughout the developed world (most recently Sweden, 2010) have kept the parasite in the public eye. Infected hosts release up to 109 oocysts per day, and the discovery of a single oocyst forces closure and loss of drinking water supplies (e.g. NW England 2015, 0.3 million homes affected). In rural Wales, the different sources of contamination are unknown, but are likely to arise from sheep farming in rural communities. These multiple sources of contamination are difficult to diagnose and monitor, and almost impossible to eliminate due to costs of complex methodologies. The huge excess production of oocysts compared to the infective dose (only 10 oocysts can start an infection) suggests that in the natural environment, most oocysts are removed biotically, probably by grazing and suspension feeding invertebrates and protists. These interactions may be adversely affected by eutrophication (connected with land use and climate change), increasing the importance of Cryptosporidium in both the developing world and in 'Blue Marble' situations within the developed world.