Health Topic

Cryptosporidiosis

Cryptosporidiosis or Crypto is an illness caused by a parasite that lives in soil, food and water. Learn the common symptoms and what you should do.

Reviewed Reviewed by a registered pharmacistGeneral information

Also called: Crypto

Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.

About 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 (poop) of humans or animals that have the infection.

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 you touch your eyes, mouth, or nose. Another way that Crypto can spread is through sexual contact.

Certain people are more likely to get Crypto; they include:

  • 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

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 with the parasite. 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. Some reasons why you might have a weakened immune system could 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.

Cryptosporidiosis is diagnosed by examining stool samples, usually under a microscope. People with Crypto can have many parasites in their stool one day but not as many the next day. So you may need to give the lab three stool samples collected on three different days. This helps make sure that your diagnosis is correct.

Most people with cryptosporidiosis get better without treatment. It usually takes about one to two weeks. It's important to drink plenty of fluids to prevent dehydration if you are pregnant. Infants and young children should also get extra fluids. They should get extra fluids. If you are pregnant or if you think that 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 talk about whether that medicine is right for you.

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. You also need to 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. This will also help prevent other sexually transmitted infections.

Centers for Disease Control and Prevention

It sits within Infections and Immune System.

The lead U.S. institute for this subject is the National Institute of Allergy and Infectious Diseases.

When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.

Research on Cryptosporidiosis

34 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.

What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.

Research currently under way

Research already completed

Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.

Where to read more

Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.

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Diagnosis and Tests

Treatments and Therapies

Prevention and Risk Factors

Related Issues

Clinical Trials

Medical subject headings

Clinicians and researchers index this subject under Cryptosporidiosis. These are the terms to use when searching medical literature.

This page is built from the MedlinePlus health topic record for Cryptosporidiosis, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.