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Cryptosporidiosis
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Infections

Cryptosporidiosis

Cryptosporidiosis is a contagious disease caused by the parasite Cryptosporidium, which is found in soil, food, and water contaminated with stool.

What is cryptosporidiosis?

Cryptosporidiosis is a contagious disease that causes watery diarrhea. It is caused by parasites called Cryptosporidium, or Crypto. These parasites live in soil, food, and water. They are found in every region of the United States and throughout the world. Crypto can also be found on surfaces or dirty hands that have been contaminated with the stool of humans or animals that have the infection.

How is cryptosporidiosis spread?

You can become infected with Crypto by swallowing the parasite if it is in your food, drinking water, or water that you swim in. You can also get infected when you touch something that has been contaminated and then touch your eyes, mouth, or nose. Another way that Crypto can spread is through sexual contact.

Who is more likely to get cryptosporidiosis?

Certain people are more likely to get Crypto, including:

  • Children and workers at childcare centers
  • Older adults (ages 75 years and older)
  • People who take care of other people with Crypto
  • International travelers
  • Backpackers, hikers, and campers who drink unfiltered, untreated water
  • People, including swimmers, who swallow water from contaminated sources
  • People who touch infected animals, often cows or sheep

What are the symptoms of cryptosporidiosis?

The most common symptom of cryptosporidiosis is watery diarrhea. Other symptoms include:

  • Dehydration
  • Weight loss
  • Stomach cramps or pain
  • Fever
  • Nausea and vomiting

The symptoms generally begin 2 to 10 days after becoming infected. In people with healthy immune systems, the symptoms can last about 1 to 2 weeks. Occasionally, the symptoms can last longer or come and go for up to 30 days.

People with weakened immune systems may develop a serious, chronic illness. Reasons for a weakened immune system include:

  • Having HIV
  • Having cancer
  • Having a genetic condition that affects the immune system
  • Taking certain medicines, such as chemotherapy and medicines needed after an organ transplant

Some people may not have any symptoms at all. Contact your health care provider if you have watery diarrhea that lasts more than a few days, especially if you have a weakened immune system.

How is cryptosporidiosis diagnosed?

Cryptosporidiosis is diagnosed by examining stool samples, usually under a microscope. Because people with Crypto can have many parasites in their stool one day but not as many the next, you may need to provide three stool samples collected on three different days to ensure an accurate diagnosis.

What are the treatments for cryptosporidiosis?

Most people with cryptosporidiosis get better without treatment in about one to two weeks. It is important to drink plenty of fluids to prevent dehydration. If you are pregnant, or if you think you or your child are severely dehydrated, contact your provider about how to get enough fluids. Some people who are dehydrated may need to get intravenous (IV) fluids in a hospital.

Over-the-counter anti-diarrheal medicine might help slow down diarrhea, but do not take it without first asking your provider. There is a medicine to treat diarrhea caused by Crypto in people with healthy immune systems; you and your provider can discuss whether that medicine is right for you.

Can cryptosporidiosis be prevented?

To lower your chance of getting or spreading Crypto:

  • Wash your hands often with soap and water, especially after using the toilet, changing diapers, or touching animals. Wash your hands before eating or preparing food. Alcohol-based hand sanitizers are not effective against Crypto.
  • Only drink water that you know is safe.
  • Only drink milk and apple cider that have been pasteurized.
  • Don't eat uncooked foods when traveling in countries where the food supply might be unsafe.
  • Never go swimming when you have diarrhea.
  • Don't swallow water when you go swimming.
  • Use condoms or dental dams every time you have sex.

Frequently Asked Questions

You should seek medical attention if you have signs of dehydration, such as dry mouth, little or no urination, dizziness, or extreme thirst. Medical care is also necessary if you are unable to keep fluids down due to vomiting, if you have a fever higher than 101.5°F (38.6°C), or if you see blood in your stool. If you have a weakened immune system, such as from HIV/AIDS, chemotherapy, or organ transplant medication, you should contact your healthcare provider immediately upon developing diarrhea, as the infection can become life-threatening in these cases.
Symptoms of cryptosporidiosis typically begin 2 to 10 days after swallowing the parasite. This incubation period means that if you have been exposed to contaminated water or food, you should monitor for signs of watery diarrhea, stomach cramps, and nausea during this window. If you are in a high-risk group, such as having a weakened immune system, symptoms may be more severe or persistent, and you should consult a healthcare provider promptly if you experience any gastrointestinal distress after potential exposure.
The most effective prevention strategy is to avoid swallowing water from untreated sources. When traveling or camping, drink only bottled water or water that has been properly treated. Boiling water for at least one minute is the most reliable method to kill the parasite, as standard chemical filters and many water purification tablets may not be effective against Cryptosporidium. Additionally, practice good hand hygiene by washing hands with soap and water or using alcohol-based hand sanitizer after using the restroom and before handling food, as the parasite can survive on surfaces and hands.
Yes, individuals with healthy immune systems can still shed the parasite in their stool and transmit the infection to others, even if they are asymptomatic or have mild symptoms. The parasite can be present in stool for several weeks after symptoms resolve. Therefore, it is crucial to practice strict hygiene, including thorough handwashing with soap and water, to prevent spreading the infection to family members, coworkers, or childcare settings. Alcohol-based hand sanitizers are not effective against Cryptosporidium, so physical washing is essential.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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