CDC National AIDS Hotline Training Bulletin #110
Centers for Disease Control and Prevention

Cryptosporidiosis (crip-toe-spor-id-i-o-sis) is a disease caused by the parasite Cryptosporidium parvum, which as late as 1976 was not known to cause disease in humans. Until 1993, when over 400,000 people in Milwaukee, Wisconsin, became ill with diarrhea after drinking water contaminated with the parasite, few people had heard of either cryptosporidiosis or the single-celled intestinal protozoon that causes it.

Since the Milwaukee outbreak, concern about the safety of drinking water in the United States has increased, and new attention has been focused on determining and reducing the risk for cryptosporidiosis from community and municipal water supplies.

Transmission

Cryptosporidiosis is spread by putting something in the mouth that has been contaminated with the stool of an infected person or animal. In this way, people swallow the Cryptosporidium parasite, which is too small to be seen with the naked eye. A person can become infected by drinking contaminated water or eating raw or undercooked food contaminated with Cryptosporidium oocysts (an egg-like form of the parasite that is the infectious stage); direct contact with the droppings of infected animals or stool of infected humans; or hand-to-mouth transfer of oocysts from surfaces that may have become contaminated with microscopic amounts of stool from an infected person or animal.

Symptoms

Two to ten days after infection by the parasite, symptoms may appear. Although some persons may not have symptoms, others have watery diarrhea, headache, abdominal cramps, nausea, vomiting, and low-grade fever. These symptoms may lead to weight loss and dehydration. In otherwise healthy persons, these symptoms usually last 1 to 2 weeks, at which time the immune system is able to stop the infection. In persons with suppressed immune systems, such as persons who have AIDS or recently have had an organ or bone marrow transplant, the infection may continue and become life-threatening.

If you suspect that you have cryptosporidiosis, see your physician as soon as possible, especially if your immune system is suppressed, to ensure that the disease can be properly identified and monitored. You may be tested for the Cryptosporidium parasite by submitting a stool sample.

Treatment

No safe and effective cure is available for cryptosporidiosis. People who have normal immune systems improve without taking antibiotic or antiparasitic medications. The treatment recommended for this diarrheal illness is to drink plenty of fluids and to get extra rest. Physicians may prescribe medication to slow the diarrhea during recovery.

Who Is At Risk?

Persons at increased risk for cryptosporidiosis include child care workers; diaper-aged children who attend day-care centers; persons exposed to human feces by sexual contact; and caregivers who might come in direct contact with feces while caring for a person infected with cryptosporidiosis at home or in a medical facility. Once infected, persons with suppressed immune systems such as AIDS patients, are at risk for severe disease.

Prevention

* Avoid water or food that may be contaminated.

* Wash hands after using the toilet and before handling food.

* If you work in a child-care center where you change children's diapers regularly, wash hands properly, or, if you use gloves, change gloves between each child.

During communitywide outbreaks caused by contaminated drinking water, boil drinking water for 1 minute to kill the Cryptosporidium parasite. Allow water to cool before drinking it.

HIV-infected persons should avoid drinking water directly from lakes or rivers; avoid unpasteurized milk or milk products; avoid exposure to calves and lambs and places where these animals are raised; wash hands after contact with pets; and wash hands after gardening or other contact with soil. Because any sexual activity that brings a person in contact with the feces of an infected partner greatly increases the risk for cryptospor- idiosis, HIV-infected persons and AIDS patients should follow "safer sex" guidelines and avoid sexual practices that may result in contact with feces.

If you are a caregiver of cryptosporidiosis patients, wash hands after bathing patients, emptying bedpans, changing soiled linen, or otherwise coming in contact with the stools of patients. If you have cryptosporidiosis, wash your hands often to prevent spreading the disease to other members of your household.

For more information on cryptosporidiosis, see the following sources:

Dubey JP, Speer CA, Fayer R. Cryptosporidiosis of man and animals. Boston: CRC Press, 1990.

LeChevallier MW, Norton WD, Lee RG. Giardia and Cryptosporidium spp. in filtered drinking water supplies. Appl Environ Microbiol 1991;57(9):2617-2621.

Rose JB, Gerba CP, and Jakubowski W. Survey of potable water supplies for Cryptosporidium and Giardia. Environmental Science and Technology 1991;25(8):1393-1400.

MacKenzie WR, Hoxie NJ, Proctor ME, Gradus SG, Blair KA, Peterson DE, Kazmierczak JJ, Addiss DG, Fox K, Rose JB, Davis JP. Massive waterborne outbreak of Cryptosporidium infection associated with a filtered public water supply, Milwaukee, Wisconsin, March and April, 1993. N Engl J Med 1994; 331:161-167.

Cordell FL, Addiss DG. Cryptosporidiosis in child care settings: a review of the literature and recommendations for prevention and control. Pediatr Infect Dis J. 1994;13(4):310-317.

Smith PD, Quinn TC, Strober W, Janoff EN, Masur H. Gastrointestinal infections in AIDS. Ann Intern Med 1992;116:63-77.

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