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June 10, 2008 - 7:30am
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What is Cryptosporidium ?

Cryptosporidiosis (krip-toe-spo-rid-e-o-sis), is a diarrheal disease caused by a microscopic parasite, Cryptosporidium parvum . It can live in the intestine of humans and animals and is passed in the stool of an infected person or animal. Both the disease and the parasite are also known as "Crypto." 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 disinfection. During the past two decades, Crypto has become recognized as one of the most common causes of waterborne disease (drinking and recreational) in humans in the United States. The parasite is found in every region of the United States and throughout the world.

What are the symptoms of Crypto ?

Symptoms include diarrhea, loose or watery stool, stomach cramps, upset stomach, and a slight fever. Some people have no symptoms. Symptoms generally begin 2 -10 days after being infected. In persons with average immune systems, symptoms usually last about two 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.

How is Crypto spread?

Crypto lives in the intestine of infected humans or animals. Millions of Crypto can be released in a bowel movement from an infected human or animal. You can become infected after accidentally swallowing the parasite. Crypto may be found in soil, food, water, or surfaces that have been contaminated with the feces from infected humans or animals. Crypto is not spread by contact with blood. Crypto can be spread by:

  • Putting something in your mouth or accidentally swallowing something that has come in contact with the stool of a person or animal infected with Crypto
  • Swallowing recreational water contaminated with Crypto (Recreational water is water in swimming pools, hot tubs, jacuzzis, fountains, lakes, rivers, springs, ponds, or streams that can be contaminated with sewage or feces from humans or animals. Note: Crypto is chlorine resistant and can live for days in pools.)
  • Eating uncooked food contaminated with Crypto
  • Accidentally swallowing Crypto picked up from surfaces (such as toys, bathroom fixtures, changing tables, diaper pails) contaminated with stool from an infected person

Should I worry about spreading infection to others?

Yes, Crypto can be very contagious. Follow these guidelines to avoid spreading Crypto to others:

  • Wash your hands with soap and water after using the toilet, changing diapers, and before eating or preparing food.
  • Avoid swimming in recreational water (pools, hot tubs, lakes or rivers, the ocean, etc.) if you have Crypto and for at least two weeks after diarrhea stops.You can pass Crypto in your stool and contaminate water for several weeks after your symptoms have ended. This has resulted in many outbreaks of Crypto among recreational water users. Note: you are not protected in a chlorinated pool because Crypto is chlorine resistant and can live for days in pools.
  • Avoid fecal exposure during sex.

Am I at risk for severe disease?

Although Crypto can infect all people, some groups are more 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, you are at risk for more serious disease. Your symptoms may be more severe and could lead to serious or life-threatening illness. Examples of persons with weakened immune systems include:

  • Those with HIV/AIDS
  • Cancer and transplant patients who are taking certain immunosuppressive drug
  • Those with inherited diseases that affect the immune system

If you have a severely weakened immune system, consult with your health care provider for additional guidance.

How is a Crypto infection diagnosed?

Your health care provider will ask you to submit stool samples to see if you are infected. Because testing for Crypto can be difficult, you may be asked to submit several stool specimens over several days. Because tests for Crypto are not routinely done in most laboratories, your health care provider should specifically request testing for the parasite.

What is the treatment for Crypto ?

There is no effective treatment. Most people with a healthy immune system will recover on their own. If you have diarrhea, drink plenty of fluids to prevent dehydration. Rapid loss of fluids because of diarrhea can be life-threatening in babies. Parents should consult their health care provider about fluid replacement therapy options for babies. Antidiarrheal medicine may help slow down diarrhea, but consult with your health care provider before taking it. People who are in poor health or who have a weakened immune system are at higher risk for more severe and more prolonged illness. For persons with AIDS, anti-retroviral therapy that improves immune status will also decrease or eliminate symptoms of Crypto . However, Crypto is usually not cured and may come back if the immune status worsens. See your health care provider to discuss anti-retroviral therapy used to improve immune status.

How can I prevent Crypto?

  • Practice good hygiene. Wash hands thoroughly with soap and water.
    • Wash hands after using the toilet and before handling or eating food (especially for persons with diarrhea).
    • Wash hands after every diaper change, especially if you work with diaper-aged children, even if you are wearing gloves.
  • Protect others by not swimming if experiencing diarrhea (essential for children in diapers).
  • Avoid water that might be contaminated.
  • Avoid swallowing recreational water.
  • Avoid drinking untreated water from shallow wells, lakes, rivers, springs, ponds, and streams.
  • Avoid drinking untreated water during community-wide outbreaks of disease caused by contaminated drinking water. In the United States, nationally distributed brands of bottled or canned carbonated soft drinks are safe to drink. Commercially packaged noncarbonated soft drinks and fruit juices that do not require refrigeration until after they are opened (for example, those that can be stored without refrigeration on grocery shelves) also are safe.
  • Avoid using ice or drinking untreated water when traveling in countries where the water supply might be unsafe. If you are unable to avoid drinking or using water that might be contaminated, then treat the water yourself by:
    • Heating the water to a rolling boil for at least 1 minute or using a filter that has an absolute pore size of at least 1 micron, or one that has been NSF-rated for "cyst removal."
  • Do not rely on chemical disinfection of Crypto because it is highly resistant to inactivation by chlorine or iodine.
  • Avoid food that might be contaminated.
  • Wash and/or peel all raw vegetables and fruits before eating.
  • Use uncontaminated water to wash all food that is to be eaten raw.
  • Avoid eating uncooked foods when traveling in countries with minimal water treatment and sanitation systems.
  • Avoid fecal exposure during sex.


Centers for Disease Control and Prevention, May 2001

Last reviewed May 2001 by ]]>EBSCO Publishing Editorial Staff]]>

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.