About Cryptosporidiosis - Minnesota Dept. of Health

About Cryptosporidiosis

Cryptosporidiosis (often called “Crypto”) is a diarrheal disease caused by the protozoan parasite Cryptosporidium spp.

Cryptosporidium is passed in the stool of an infected person or animal. The parasite is protected by an outer shell that allows it to survive outside the body for long periods of time and is highly resistant to chlorine.

Cryptosporidiosis is a common cause of waterborne illness and is the most common cause of recreational water illness (RWI) outbreaks in the United States. Approximately 350-450 cases of Crypto are diagnosed in Minnesota each year.

On this page:
Fact Sheet

Control Measures

Fact Sheet


Cryptosporidium can live in the intestines of humans and animals and is passed in the stool of an infected person or animal. Millions of Crypto organisms (oocysts) can be released in the bowel movement of an infected human or animal. You can become infected after accidentally ingesting the oocysts.

Crypto may be found in soil, food, water, or surfaces that have been contaminated with the feces of infected humans or animals.

Common ways Cryptosporidium is transmitted include:

  • Swallowing contaminated water while swimming or drinking.
  • Having contact with animals, especially calves and goats, and their environment.
  • Having contact with people who are sick with cryptosporidiosis, especially in child care settings.
  • Swallowing Cryptosporidium oocysts picked up from contaminated surfaces, like changing tables, door handles, and toys.
  • Drinking raw (unpasteurized) milk and apple cider.
  • Eating foods contaminated with the parasite.
  • Exposure to fecal material during sexual activity.


Symptoms include:

  • Watery diarrhea
  • Stomach cramps
  • Loss of appetite
  • Weight loss
  • Slight fever
  • Vomiting

Symptoms generally begin a week after exposure but can begin as short as 2 days or as long as 2 weeks after exposure to the parasite.

In people with healthy immune systems, symptoms usually last about 2 weeks. The symptoms may go in cycles in which you may seem to get better for a few days, then feel worse, before the illness ends.


Most people with healthy immune systems will recover from their Cryptosporidium infection on their own. Approximately 10% of cases require hospitalization.

People with compromised immune systems, for example, people with AIDS, cancer and transplant patients taking immunosuppressive medications, and people with inherited immune diseases, may have more severe symptoms and the infection may persist indefinitely.


Cryptosporidiosis is diagnosed by testing a stool (poop) specimen for the parasite.


Most people with healthy immune systems do not need any specific treatment and will recover from their Cryptosporidium infection on their own. Diarrhea should be managed by drinking plenty of fluids to prevent dehydration.

Nitazoxanide is the only drug approved by the Food and Drug Administration to treat patients aged 1 year or older with diarrhea associated with cryptosporidiosis. The effectiveness of nitazoxanide in immunosuppressed people is unclear. Contact your health care provider to discuss treatment options.


You can minimize your risk of getting cryptosporidiosis by following these recommendations:

  • Wash hands after using the bathroom and changing diapers, and before handling or eating any food.
    • Alcohol-based hand sanitizers are not effective against Cryptosporidium. Soap and water must be used.

  • Do not swallow water while swimming.
    • Cryptosporidium is chlorine resistant and can survive in even properly treated swimming pools for days.

  • Wash hands after contact with farm animals, pets, animal poop, and animal environments.
  • Do not drink untreated water from lakes, rivers, springs, ponds, and streams. If you are unable to avoid drinking water that might be contaminated, learn how to treat your water properly.
    • Do not drink raw (unpasteurized) milk or apple cider. 

    • Use caution when traveling in countries with minimal water treatment and sanitation systems by avoiding tap water, fountain drinks, ice, and raw foods.
    • Reduce fecal-oral exposure during sexual activity and avoid sexual activity with those who have diarrhea or who recovered from cryptosporidiosis in the last 2 weeks.

Control Measures

People who are infected with Cryptosporidium shed the parasite in their stool while they are having symptoms and for about 2 weeks after their symptoms have stopped. Because the drug to treat Cryptosporidium infections, nitazoxanide, does not always kill the parasite, the same precautions should be taken whether someone has been treated or not.

People who have symptoms of cryptosporidiosis can reduce the risk of spreading their illness to others by following these recommendations:

  • Wash hands carefully and frequently with soap, especially after using the bathroom and changing diapers, and before handling or eating any food.
  • Stay out of pools, splash pads, and lakes while sick. If diagnosed with cryptosporidiosis, do not swim for at least 2 weeks after diarrhea stops.
  • Do not bathe with others while sick and for at least 2 weeks after diarrhea stops.
  • Do not attend or work in child care or preschool until 24 hours after diarrhea stops.
  • Wait to have sex until 2 weeks following the end of symptoms.

Do you suspect that you have a foodborne or waterborne illness? Visit reporting suspected foodborne/waterborne illnesses.

Updated Tuesday, 05-Nov-2019 11:05:54 CST