Cryptosporidiosis is a gastrointestinal infection caused by the parasite Cryptosporidium. Transmission occurs via fecal-oral contact through ingestion of contaminated water or from person to person.

What is cryptosporidiosis? 

Cryptosporidiosis is caused by Cryptosporidium sp, a small parasite. The parasite can live in the intestines (intestinal epithelial cells) of several mammals and in humans.

There are several species of Cryptosporidium, but only Cryptosporidium parvum causes infections in humans.

The parasite is found throughout the world and can cause sporadic cases or epidemics.


Cryptosporidiosis occurs in all ages. In healthy individuals, the infection causes no symptoms or a trivial gastrointestinal infection (gastroenteritis).

Symptoms appear 7 to 10 days after infection:

  • diarrhoea
  • stomach cramps
  • fever
  • nausea.

The symptoms disappear spontaneously after a few days to weeks.

In patients with compromised immune systems, such as AIDS patients, the infection causes severe, sometimes cholera-like diarrhoea with fever for which the patient may have to receive nutrition via IV drip sometimes for several months.


Farm animals, especially ruminants, and humans themselves are an important source of infection with Cryptosporidium. Humans are infected through the fecal-oral route: through direct human-to-animal contact, direct human-to-human transmission, as well as indirectly through drinking water, surface water and swimming pool water contaminated with feces or through contaminated food. Food can become contaminated through irrigation with contaminated surface water, for example, but transmission can also occur through an infected person preparing food.


The infection is transmitted primarily through contaminated water (and food) or from person to person.

To prevent transmission, hygiene regulations must be strictly followed.

  • Wash and clean:
    • wash your hands after going to the toilet to prevent spreading
    • wash your hands when changing nappies
    • wash your hands after contact with farm animals
    • wash your hands before cooking.
  • Wash fruit and vegetables first with (clean) water.
  • Use clean water and sanitation facilities. If these are not available, as may be the case when you are on holiday, for example, drink only water that you know has been boiled/disinfected first or bottled/canned soft drinks. Beware of ice cubes.


The diagnosis is made by detecting the parasite in the stool or through an intestinal biopsy.

Risk groups

Patients with compromised immune defences (e.g. untreated AIDS patients, chemotherapy) are at higher risk of more severe progression of the illness.


Cryptosporidioses are usually benign diseases that do not require special treatment. However, proper care must be taken to take in sufficient fluids by drinking plenty of water. For prolonged or severe symptoms, a doctor may initiate treatment if necessary.

Sciensano contributes to the epidemiological surveillance of cryptosporidiosis in Belgium. This is done in cooperation with laboratories and regional authorities.

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