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What is cryptosporidiosis?
Cryptosporidiosis is an intestinal illness caused by a germ (a parasite) called Cryptosporidium parvum. It was first recognized as a cause of human illness in 1976, but it gained national attention in the spring of 1993 after approximately 400,000 people in Milwaukee became ill with diarrhea after drinking water contaminated with this parasite.
What are the symptoms?
The most common symptom is watery diarrhea. Other signs and symptoms include weight loss, stomach cramps, nausea, vomiting, headache and mild fever. These symptoms generally appear within 2 to 14 days of swallowing the parasite. In otherwise healthy people, these symptoms usually go away on their own in between 1 and 20 days (average 10). Some people might not have any symptoms at all. However, in people with weakened immune systems, the symptoms are more severe, last longer and can lead to severe dehydration and even death.
How is cryptosporidiosis spread?
Infection occurs after the parasite is swallowed. The parasite is found in the stool (feces) of infected people and animals, especially cattle. Thus, the disease can be spread from one person to another if an infected person prepares food for other people without thoroughly washing his or her hands after using the toilet, taking care of an infected person with diarrhea, or caring for diapered children. The germs can also spread by drinking contaminated water. In rare cases, cryptosporidiosis can be spread through lakes and swimming pools when people who have diarrhea swim in the water. The parasites can live in the water and infect other swimmers, particularly those who swallow the water.
Who gets cryptosporidiosis?
Anyone can get a cryptosporidium infection. People at greatest risk for severe illness are those with weakened immune systems such as people with HIV infection, on chemotherapy or on high-dose steroid therapy after organ transplantation.
How is the disease diagnosed and treated?
Cryptosporidiosis is diagnosed by identifying the parasite in a stool sample. A limited number of medications are available which may be helpful in treating the infection. Fluid replacement is needed if the person is dehydrated. Consult your health care provider for more information.
How can cryptosporidiosis be prevented?
The following steps can be taken to minimize your chance of getting and spreading infection:
  • Always wash your hands after using the toilet, changing diapers and before handling food.
  • Wash your hands after contact with animals, especially cattle.
  • Do not drink directly from streams, brooks or lakes when hiking or camping.
  • Avoid drinking water that has not been boiled when traveling in developing countries or whenever else you are unsure of the drinking water quality. Bring water to a rolling boil for one minute to eliminate cryptosporidium.
  • Comply with any water advisories issued by local and state authorities. In Massachusetts, the likelihood that cryptosporidium would be a problem if regulated public drinking water is low.
People having problems with their immune system may have a more severe illness if they are infected with the parasite, and they may want to consider following these additional recommendations:
  • Be particularly careful to avoid fecal contact (contact with stool).
  • Bring tap water to a rolling boil for one minute before drinking it or making ice cubes with it.
  • Consider the use of a home water filtering system with a very fine filter (with an absolute pore size of 1 micron or smaller). Such filters include: reverse-osmosis filters; filters labeled as “absolute” 1 micron filters; and those labeled as meeting National Sanitation Foundation (NSF) standard #53 for cyst removal. Use the home water filtering system according to manufacturers’ instructions. Note: Commercial bottled water may be used, but it is not checked for cryptosporidium and cannot be guaranteed to be free of this parasite. For more information about water filters, contact the NSF at 789 North Dixboro Road, P.O. Box 130140, Ann Arbor, Michigan 48113-0140. Telephone: (877) 867-3435.
  • Avoid swallowing water when swimming. Lakes, streams (and other surface waters) and swimming pools may be contaminated with cryptosporidium, and chlorination is not effective in eliminating the parasite.
Are there any restrictions for people with cryptosporidiosis?
Yes. Because cryptosporidiosis is a disease that can spread to other people, health care providers are required by law to report cases of cryptosporidiosis to the local board of health. In order to protect the public, workers at food-related businesses who have cryptosporidiosis must stay out of work until they don’t have diarrhea and one lab test on a stool sample shows that there are no cryptosporidium germs. Workers in food-related businesses who have diarrhea and live with someone who has cryptosporidiosis must also show that they have no cryptosporidium in their stool. Food-related businesses include restaurants, sandwich shops, hospital kitchens, supermarkets, dairy or food-processing plants. This regulation also includes workers in schools, residential programs, day-care and health care facilities who feed, give mouth care or dispense medications to clients.​
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