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Cryptosporidium

What is Cryptosporidium?

Cryptosporidiosis is a diarrheal disease caused by microscopic parasites, Cryptosporidium, that can live in the intestine of humans and animals and 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 makes it very resistant to chlorine-based disinfectants.

During the past 2 decades, Cryptosporidium has become recognized as one of the most common causes of waterborne disease (recreational water and drinking water) in humans in the United States. 

The parasite is found in every region of the United States and throughout the world.

Both the disease and the parasite are commonly known as “Crypto.”

People who are in poor health or who have weakened immune systems are at higher risk for more severe and more prolonged illness.

How is Crypto spread?

You can become infected after accidentally swallowing the parasite. 

Crypto lives in the gut of infected humans or animals. An infected person or animal sheds Crypto parasites in their poop. An infected person can shed 10,000,000 to 100,000,000 Crypto germs in a single bowel movement.

Shedding of Crypto in poop begins when symptoms like diarrhea begin and can last for weeks after symptoms stop. Swallowing as few as 10 Crypto germs can cause infection.

Crypto is not spread by contact with blood.

Who is at risk for Infection?

  • Children who attend day care centers, including diaper-aged children
  • Child care workers
  • Parents of infected children
  • People who take care of other people with cryptosporidiosis
  • International travelers
  • Backpackers, hikers, and campers who drink unfiltered, untreated water
  • People who drink from untreated shallow, unprotected wells
  • People, including swimmers, who swallow water from contaminated sources
  • People who handle infected cattle

What should I do if I think I might have cryptosporidiosis?

For diarrhea whose cause has not been determined, the following actions may help relieve symptoms:

  • Drink plenty of fluids to remain well hydrated and avoid dehydration. Serious health problems can occur if the body does not maintain proper fluid levels. For some people, diarrhea can be severe resulting in hospitalization due to dehydration.
  • Maintain a well-balanced diet. Doing so may help speed recovery.
  • Avoid beverages that contain caffeine, such as tea, coffee, and many soft drinks.
  • Avoid alcohol, as it can lead to dehydration.


Contact your healthcare provider if you suspect that you have cryptosporidiosis.

Common symptoms of Crypto

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

Some people with Crypto will have no symptoms at all.

While the small intestine is the site most commonly affected, Crypto infections could possibly affect other areas of the digestive tract or the respiratory tract.

Symptoms of crypto generally begin 2 to 10 days (average 7 days) after becoming infected with the parasite. In persons with healthy immune systems, symptoms usually last about 1 to 2 weeks. The symptoms may go in cycles in which you may seem to get better for a few days, then feel worse again before the illness ends.

Cryptosporidium: 1982 CDC/Dr. Edwin P Ewing, Jr.

Crypto can be very contagious

To avoid spreading the disease to others, infected individuals should wash their hands frequently with soap and water, especially after using the toilet, or changing diapers, and before eating or preparing food.

If you think you may have crypto see your healthcare provider. Thoroughly wash with clear, clean (uncontaminated) water, all vegetables and fruits you plan to eat raw.

The risks of Cryptosporidium

Contaminated water may include water that has not been boiled or filtered, as well as contaminated recreational water sources (e.g., swimming pools, lakes, rivers, ponds, and streams).

Several community-wide outbreaks of cryptosporidiosis have been linked to drinking municipal water or recreational water contaminated with Cryptosporidium

Although crypto can infect all people, some groups are likely to develop more serious illness.

  • Young children and pregnant women may be more susceptible to the dehydration resulting from diarrhea and should drink plenty of fluids while ill.
  • If you have a severely weakened immune system (including persons with AIDS; cancer and transplant patients taking certain immunosuppressive drugs; and those with inherited diseases that affect the immune system, etc.) you are at risk for more serious disease. Your symptoms may be more severe and could lead to serious or life-threatening illness.

Diagnosing a crypto infection

Cryptosporidiosis is a diarrheal disease that is spread through contact with the stool of an infected person or animal. The disease is diagnosed by examining stool samples.

People infected with Crypto can shed the parasite irregularly in their poop (for example, one day they shed parasite, the next day they don’t, the third day they do) so patients may need to give three samples collected on three different days to help make sure that a negative test result is accurate and really means they do not have Crypto.

Healthcare providers should specifically request testing for Crypto. Routine ova and parasite testing does not normally include Crypto testing.

Treatment for Cryptosporidium

FDA-Approved Treatment

Nitazoxanide has been FDA-approved for treatment of diarrhea caused by Cryptosporidium in people with healthy immune systems and is available by prescription. Consult with your healthcare provider for more information.

Most people who have healthy immune systems will recover without treatment. Diarrhea can be managed by drinking plenty of fluids to prevent dehydration. Young children and pregnant women may be more susceptible to dehydration. Rapid loss of fluids from diarrhea may be especially life threatening to babies
Parents should talk to their healthcare provider about fluid replacement therapy options for infants. Anti-diarrheal medicine may help slow down diarrhea, but a health care provider should be consulted before such medicine is taken.

People who are in poor health or who have weakened immune systems are at higher risk for more severe and more prolonged illness. The effectiveness of Nitazoxanide in immunosuppressed individuals is unclear. HIV-positive individuals who suspect they have Crypto should contact their health care provider. For persons with AIDS, anti-retroviral therapy that improves immune status will also decrease or eliminate symptoms of Crypto. However, even if symptoms disappear, cryptosporidiosis is often not curable and the symptoms may return if the immune status worsens.

How can I help
prevent the spread of crypto?

No cleaning method is guaranteed to be completely effective against Crypto. However, you can lower the chance of spreading Crypto by taking the following precautions:

* Wash linens, clothing, dishwasher- or dryer-safe soft toys, etc. soiled with poop or vomit as soon as possible.
+ Flush excess vomit or poop on clothes or objects down the toilet.
+ Use laundry detergent, and wash in hot water: 113°F or hotter for at least 20 minutes or at 122°F or hotter for at least 5 minutes.
+ Machine dry on the highest heat setting.

More Prevention

*For other household objects and surfaces (for example, diaper-change areas):
+ Remove all visible poop.
+ Clean with soap and water.
+ Let dry completely for at least 4 hours.

If possible, expose to direct sunlight during the 4 hours.

* Wash your hands with soap and water after cleaning objects or surfaces that could be contaminated with Crypto.