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What is cryptosporidiosis?

Cryptosporidiosis is a disease caused by an intestinal parasite. Watery diarrhea and often abdominal cramping are the major symptoms. Other symptoms include nausea, vomiting, fatigue, weight loss and low-grade fever. In some patients, symptoms will come and go and in other patients they will be persistent. Symptoms usually occur about a week after exposure, but can begin as soon as one day or as late as 12 days after exposure.

How do you get cryptosporidiosis?

The parasite Cryptosporidium parvum is found in the feces of infected animals and people. Persons, dogs and cats become infected when they swallow this parasite. This is one reason why hands should be washed after contact with pets. Hands also should be washed after changing a child's diaper and after using the toilet. Other activities that bring a person in contact with feces of another person can result in exposure. The parasite, which can be present in sewage or runoff from feed lots, can contaminate water sources, and several large waterborne outbreaks have occurred. Outbreaks also have occurred in child day care centers. In Illinois, 75-100 cases of cryptosporidiosis are reported annually.

How serious is cryptosporidiosis?

Symptoms can last for up to 30 days in persons who are otherwise healthy. In persons with weakened immune systems, including people with HIV/AIDS and cancer, transplant patients taking immunosuppressive drugs and people with genetically weakened immune systems, symptoms can persist indefinitely. Persistent diarrhea due to cryptosporidiosis in these persons can lead to death.

How is cryptosporidiosis diagnosed?

The patient's physician can order a special test to detect the presence of Cryptosporidium in a stool specimen. Routine stool examinations will not detect this parasite.

How is cryptosporidiosis treated?

There is no effective cure for cryptosporidiosis. Persons with this disease should drink plenty of fluids and get extra rest. Physicians may prescribe medication to slow the diarrhea during recovery.

What should I do to protect myself against cryptosporidiosis?

  • Wash hands after handling pets or other animals.
  • Wash hands after handling items that might be contaminated with the feces of other persons.
  • Wash hands before preparing or handling food.
  • Wash hands after gardening or other contact with soil.
  • Wash produce thoroughly before eating.
  • Avoid unpasteurized milk or milk products.
  • Avoid exposure to calves and lambs and places where these animals are raised.
  • Avoid sexual contact with other persons that involves exposure to their feces. Follow "safer sex" guidelines.
  • Avoid drinking water directly from rivers, lakes and streams.

What is the correct way to wash hands?

  • Use a running stream of warm water.
  • Lather hands vigorously with soap for at least 15 seconds.
  • Rinse hands under running warm water so that the water flows from the wrist to the fingertips.
  • Dry hands.
  • If in a public place, turn off water faucet with a disposable paper towel after drying hands.

Are public water supplies free of Cryptosporidium?

Not necessarily. Cryptosporidium is common in the lakes and rivers that many public water supplies use. It is highly resistant to disinfection and even well-operated water treatment systems cannot ensure that drinking water will be completely free of Cryptosporidium.

Should I drink water from the public water supply?

If an outbreak of waterborne cryptosporidiosis is occurring in your community, boil water before drinking, drink bottled water, or drink water that has passed through a special filter. These protective measures must be used consistently in order to protect against infection.

It is not known whether severely immunocompromised persons are at increased risk if no waterborne outbreak of cryptosporidiosis is occurring in their communities. The risk is likely to vary from city to city, depending on the quality of the city's water source and the quality of water treatment. Current data do not support a recommendation that severely immunocompromised persons in all U.S. cities boil or avoid drinking tap water. Immunocompromised persons should consult with their physicians about what measures are best for them.

What are my choices if my doctor advises me not to drink regular tap water?

  • Boil water before drinking or before using it for cooking by boiling water for one minute or longer to deactivate any germs (pathogens) in the water.
  • Use a "point-of-use" (personal use, end-of-tap, under sink) filter. Only point-of-use filters that remove particles one micrometer or less in diameter should be considered. Filters in this category that provide the greatest assurance ofCryptosporidium removal include those that use reverse osmosis, those labeled as "absolute" one micrometer filters, or those certified by NSF (National Sanitation Foundation) International under Standard 53 for "cyst removal." The "nominal" one micrometer filter rating is not standardized and many filters in this category may not reliably remove Cryptosporidium. As with all filters, people should follow the manufacturer's instructions for filter use and replacement. ("Point-of-use" filters meeting the above criteria may not necessarily remove organisms other than Cryptosporidium that could pose a health hazard for severely immunocompromised individuals.)
  • Use bottled water. Water sources (wells, springs, municipal tap water) and bottled water treatment processes vary considerably. Therefore, individuals should not presume that all bottled waters are absolutely free of Cryptosporidium. Bottled waters derived from protected well and spring water sources are less likely to be contaminated by Cryptosporidium than bottled municipal drinking water because municipal drinking water is typically derived from less protected sources, such as rivers and lakes. Cryptosporidiosis has been acquired from contaminated well water, but water treated by distillation or reverse osmosis before bottling assures Cryptosporidium removal. Water passed through a filter that meets the above criteria for a "point-of-use" device before bottling will provide nearly the same level of Cryptosporidium removal as distillation or reverse osmosis. Bottled waters meeting the above criteria may not necessarily be free of organisms other than Cryptosporidium that could pose a health hazard for severely immunocompromised individuals.

To obtain a list of filters that meet NSF criteria, write to:

NSF International
3475 Plymouth Road
P.O. Box 130140
789 N. Dixboro Road
Ann Arbor, MI 48113-0140

Individuals who contact bottlers or filter manufacturers for information should request data supporting claims that a brand of bottled water or filter can meet the above criteria.