This microscopic parasite causes diarrhoea in humans that varies in degree from mild to severe.
Most infected people recover naturally within a couple of weeks of infection. But in immunocompromised people infection can be severe and prolonged and may contribute to death.
Cryptosporidiosis is normally spread through the ingestion of contaminated water, with some outbreaks related to contamination of public swimming pools.
The Sydney water crisis made Cryptosporidium spp. famous in Australia when levels of the parasite were discovered in Sydney's drinking water supply in 1998. A health alert was issued recommending that residents boil all water prior to use - a simple but effective method to prevent infection.
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