Cryptosporidium is a protozoan parasite (a tiny organism) that causes an infection called cryptosporidiosis affecting people and cattle.
The most common symptom is watery diarrhoea, which can range from mild to severe.
Cryptosporidiosis is most common in children aged between 1 and 5 years, but it can affect anyone. People with weak immune systems are likely to be most seriously affected.
There is no specific treatment for cryptosporidiosis. Most people with a healthy immune system will recover within one month. It is important to drink plenty of fluids to avoid dehydration.
Cryptosporidium is found in soil, food, water, or surfaces that have been contaminated with infected human or animal faeces. Transmission occurs through animal-to-human or human-to-human contact. People may also be infected by consuming contaminated water or food, or by swimming in contaminated water (for example in lakes or rivers). Infection is frequently associated with foreign travel.
Public Health England provides advice on controlling outbreaks of cryptosporidiosis. We monitor any outbreaks to try to find the source of the infection, so that we can help to prevent other people from becoming infected.