DOH Logo


Cause: Various species of the protozoan Cryptosporidium, which form resistant oocysts.

Illness and treatment:  Symptoms may be prolonged, and include watery diarrhea, abdominal pain, nausea, vomiting, weight loss and fever. An anti-protozoal drug is available to treat persistent symptoms.

Sources: Cryptosporidia are common in animals. In this country oocysts are found in most surface waters tested. Transmission is by ingesting fecally contaminated water, milk or food, or by direct contact with infected animals or humans. Those with asymptomatic infections may infect others. Outbreaks have occurred in water parks, swimming pools and child care facilities.

Additional risks: For persons with weakened immune systems, especially those with advanced HIV infection, the disease can be severe and persistent. Cryptosporidia resist standard chemical disinfectants and may occur in municipal water systems, home filtered water, or bottled water.

Prevention: Wash hands thoroughly after contact with animals, particularly calves or animals with diarrhea. Avoid swallowing water during water recreation. Do not drink untreated surface water. Boil untreated drinking water for one minute or use other appropriate water treatment.

Recent Washington trends: After an increase in case reporting during 2005, following changed treatment and diagnostic practices, case rates have stabilized to between 95 and 139 cases per year in Washington.

Purpose of Reporting and Surveillance

  • To identify outbreaks and potential sources of ongoing transmission.
  • To prevent further transmission from such sources.
  • To educate people about how to reduce their risk of transmission.

Legal Reporting Requirements

  • Health care providers: notifiable to local health jurisdiction within 3 business days
  • Health care facilities: notifiable to local health jurisdiction within 3 business days
  • Laboratories: Cryptosporidium notifiable to local health jurisdiction within 2 business days. Specimen submission is on request only.
  • Local health jurisdiction: notifiable to the Washington State Department of Health Communicable Disease Epidemiology (CDE) within 7 days of case investigation completion or summary information required within 21 days.