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Fact Sheet: Cryptosporidiosis


What is cryptosporidiosis?

    Cryptosporidiosis (often called "crypto") is a diarrheal disease caused by a one-celled parasite called Cryptosporidium parvum. Few people had heard of crypto until 1993, when over 400,000 people in Milwaukee, Wisconsin, became ill after their drinking water became contaminated with the parasite. Large outbreaks and isolated cases of crypto have been identified in Oregon as well. This has focused attention on determining and reducing the risk for cryptosporidiosis from community and municipal water supplies. Only about 30 crypto cases are reported in Oregon each year, but undoubtedly many thousands of infections go unreported.

How is cryptosporidiosis spread?

    People get infected when they swallow microscopic Cryptosporidium oocysts (the egg-like infectious forms of the parasite), which are shed in the feces of infected animals or people. This can happen by drinking contaminated water, through contact with infected humans or animals, or from exposure to surfaces or foods that may have become contaminated. Cattle are an important source of these parasites, but they can also be carried by other farm animals, pets, and some wild animals.

What are the symptoms of cryptosporidiosis?

    Common symptoms include watery diarrhea, abdominal cramps, nausea, vomiting, and low-grade fever. These symptoms may lead to weight loss and dehydration. Some people are infected but do not get any symptoms. They can still spread the infection to other people, however, especially if they are not careful about hand washing after using the toilet.

How soon after exposure do symptoms appear?

    Symptoms usually develop between 2 to 12 days after exposure, most commonly after about a week.

How long do symptoms last?

    For most people, symptoms last for a week or two, although some people may be sick for more than a month. In persons with suppressed immune systems, for example persons with AIDS, some cancers, or recent organ transplants, the infection may persist indefinitely, and symptoms may be more severe.

What is the treatment for cryptosporidiosis?

    Unfortunately, no drugs have been found that are effective against this bug. Drinking plenty of fluids and getting extra rest are the primary treatments. For patients with severe symptoms, doctors may recommend additional treatment.

Who is at risk?

    Crypto can strike anyone, but some people are at especially high risk of getting infected. These include children and adults who have contact with kids in diapers, childcare workers, raw milk drinkers, and people who work around cattle. Persons with AIDS or other immunosuppressive conditions are at higher risk for severe illness.

What can I do to prevent cryptosporidiosis?

  • Avoid drinking water that may be contaminated. This includes water in lakes, rivers, streams, and swimming pools. Boil or filter stream water that you will drink if you go camping.
  • For the safety of others, kids who are not toilet trained should use specifically designed "swim diapers" while swimming.
  • No one (kids or adults) should go swimming if they have diarrhea.
  • Raw (unpasteurized) milk and apple cider have been repeatedly identified as sources of crypto; drink at your own risk!
  • Wash your hands thoroughly with plenty of soap and warm water after using the toilet.
  • Wash your hands after changing diapers, emptying bedpans, or changing soiled linen, even if you wear gloves.
  • Don't take your kids to childcare if they have diarrhea.
  • Wash their hands after touching animals or cleaning up their droppings, or after visiting barns or other areas where animals are kept.
  • Wash hands before handling food.
  • Wash fresh produce thoroughly (and hope for the best!)
  • If your drinking water may be contaminated, you can kill the crypto parasite and other bugs that cause illness by boiling it for 1 minute. (Anything longer is unnecessary.) Allow water to cool before drinking it (unless you're making coffee!).
  • Tap water is considered safe in Oregon and throughout the United States. Nonetheless, HIV-infected persons may want to consider routinely boiling tap water for extra protection. Contact the Oregon Health Services or your physician for more information.

Issued by: The Oregon Health Services
Date: May, 1998. Revised 01/28/99. Return to top