Cryptosporidium infection (cryptosporidiosis) is a disease caused by tiny cryptosporidium parasites. The parasites (cryptosporidia) enter the body and travel to the small intestine and burrow into the intestinal walls. Later, cryptosporidia are shed in the feces.

A cryptosporidium infection causes watery diarrhea in healthy people and the infection goes away within a couple of weeks. However, in people with compromised immune systems the infection can become life threatening without the appropriate treatment.

Practicing good hygiene and avoiding swallowing water from public places (pools, water parks, lakes) can help prevent cryptosporidium infection.



Symptoms of cryptosporidium infection include:


  • Watery diarrhea
  • Dehydration
  • Lack of appetite
  • Weight loss
  • Fever
  • Stomach cramps or pain
  • Nausea
  • Vomiting



Cryptosporidium infection begins with ingesting the cryptosporidium parasite. Some strains of the parasite can cause a more serious disease.

The parasites settle into the walls of the intestines and eventually more cells are produced and shed in large quantities in the feces where they are highly contagious.


Methods of infection include:


  • Drinking contaminated water
  • Swimming in contaminated water
  • Eating uncooked, contaminated food
  • Touching the hand to the mouth (if the hand was in contact with a contaminated surface)
  • Close contact with other infected people or animals


Cryptosporidium parasites are one of the most common causes of diarrhea in humans. The parasite is difficult to eradicate due to its resistance to many chlorine-based disinfectants. However, the parasite can be destroyed by freezing or boiling.


Risk factors

Risk factors for cryptosporidiosis include:

  • Being exposed to contaminated water
  • Children, particularly those wearing diapers, who attend child care centers
  • Parents of infected children
  • Child care workers
  • Animal handlers
  • Engaging in oral-to-anal sexual activity
  • International travelers, especially those traveling to developing countries
  • Backpackers, hikers and campers who drink untreated, unfiltered water
  • Swallowing water in pools, lakes and rivers
  • Drinking water from shallow, unprotected wells



Complications of cryptosporidiosis include:


  • Malnutrition or malabsorption of nutrients
  • Severe dehydration
  • Significant weight loss (wasting)
  • Inflammation of a bile duct
  • Inflammation of the gallbladder, liver or pancreas



There is no vaccine to prevent a cryptosporidium infection. The infection is contagious so certain precautions should be taken to avoid infection or spreading the infection to others.


  • Practicing good hygiene
  • Thoroughly washing of fruits and vegetables in uncontaminated water
  • Purifying drinking water
  • Avoid swimming in public places
  • Avoid fecal exposure
  • Handling newborn farm and domestic animals with care