NSW Health

Cryptosporidium parvum is the parasite responsible for cryptosporidiosis, a diarrhoeal illness in humans, but it can also occur in a variety of animals such as cattle and sheep. In an infected person, the parasite invades and multiplies in the gastro-intestinal tract, causing illness and producing oocysts, the infective form of the parasite. Oocysts pass out in the faeces to the environment where they can survive for a long time, including in water.As oocysts are resistant to standard levels of chemicals, such as chlorine and bromine used for pool disinfection, Cryptosporidium transmission in public swimming pools and spas is a real public health risk.

Cryptosporidiosis transmission is faecal-oral, including person to person, animal to person, waterborne and foodborne transmission.Animal droppings and human faeces containing oocysts contaminate hands because of poor hygiene practices, but oocysts are also deposited in soil, water and food.