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Cryptosporidiosis (Crypto)

What is Cryptosporidiosis (Crypto)? Cryptosporidiosis is a diarrheal illness caused by a parasite, Cryptosporidium parvum. The parasite lives in the intestines of humans and animals and is passed in the stool of an infected animal (especially cattle and sheep) or person. The parasite is able to survive outside of the body for a long time because it has an outer shell that protects it. This shell makes the parasite very resistant to chlorine disinfection.


  • Cryptosporidiosis (Crypto) Fact SheetCryptosporidiosis (Crypto) Fact Sheet (PDF 76KB)
    View, download and print the Cryptosporidiosis (Crypto) Fact Sheet. Cryptosporidiosis is a diarrheal illness caused by a parasite, Cryptosporidium parvum. The parasite lives in the intestines of humans and animals and is passed in the stool of an infected animal (especially cattle and sheep) or person.

What are the signs and symptoms of Cryptosporidiosis?

Some people who are infected with Cryptosporidiosis do not show any symptoms. Other people will have watery diarrhea lasting 1 to 2 weeks, stomach cramps, nausea, loss of appetite and vomiting especially in children.

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How long after contact with Cryptosporidiosis will symptoms appear?

Symptoms will usually develop between one to 12 days (average seven days) after swallowing the parasite.

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How long will symptoms last?

In healthy people, the illness will usually last one to two weeks. Symptoms may come and go within this time period. In people with weakened immune systems, infection can be chronic and life threatening.

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How is Cryptosporidiosis spread?

The most common way that Cryptosporidium is spread is through drinking water or recreational water. Infection happens after swallowing the parasite. It may also be found in soil, food or surfaces that have been contaminated with the feces from an infected human or animal. Cryptosporidium can be spread:

  • By eating food or drinking water that has been contaminated by the feces of people or animals that are infected with Cryptosporidium.
  • By swallowing recreational water contaminated with Cryptosporidium such as swimming pools, hot tubs, jacuzzis, fountains, lakes, rivers, springs, ponds, or streams that can be contaminated with sewage or feces from humans or animals. Note: Cryptosporidium is chlorine resistant and can live for days in pools.
  • By eating uncooked and unwashed food contaminated with Cryptosporidium.
  • By coming into contact with feces during sexual practices.

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How is Cryptosporidiosis infection prevented?

Proper Hand Washing

  • Make sure hands are properly washed with soap and water after using the toilet, changing diapers, before eating and preparing food and after touching pets, farm or wild animals.
  • The six steps to good hand washing are:
  1. Wet hands with warm running water
  2. Put liquid soap on hands
  3. Lather hands and scrub for 20 seconds
  4. Rinse under running water
  5. Dry your hands with paper towels
  6. Use the towel to turn off the taps

If you have diarrhea, stay out of swimming pools.

  • Do not swim in recreational waters such as pools, hot tubs or Jacuzzi for at least two weeks from when diarrhea ends. The parasite is very resistant to chlorine and can live for days in chlorine-treated swimming pools and would then infect others who swam in the same water.

Pasturized milk and milk products and safe drinking water

  • Only drink pasteurized milk or milk products.
  • Avoid drinking water from rivers, creeks, lakes, shallow wells, springs, ponds and streams.
  • Only consume ice or drink treated water when traveling in countries where the water supply might be unsafe.
  • When traveling, camping or hiking or if a “boil water” advisory has been issued bring the water to a boil for 1 full minute. This water should be used for drinking, brushing teeth, rinsing dentures or contact lenses, making ice cubes, washing uncooked fruits and vegetables, and in recipes requiring water. Dishes should be washed with water that has been boiled.
  • The parasite is not killed with chemical disinfectants. If using a filter for drinking water, choose a filter that can remove particles 0.1-1.0 micrometers in diameter.

Safe Food Handling

  • Always wash vegetables and fruits with treated water before you eat them.
  • Make sure all food that comes from animal sources is cooked well.

Sexual Practices

  • Avoid sexual activity that involves anal contact.

Prevent the spread of illness by staying home

If you are sick with crypto and you:

  • work as a food handler or
  • are a healthcare worker or day care staff

stay off of work until you are 24 hours symptom free in order to prevent spreading the illness to others.

  • If your child has diarrhea caused by the parasite crypto, avoid sending your child to daycare until 24 hours after the last diarrhea.

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Date of creation: July 14, 2014
Last modified on: January 11, 2016


1Centers for Disease Control and Prevention. (November 2010) “Cryptosporidiosis” Retrieved on July, 2014 from Retrieved from
2Heymann, D.L. (2015). Control of Communicable Diseases Manual (20th Ed.) Washington, D.C.: American Public Health Association
3Ministry of Health and Long-Term Care. Infectious diseases protocol. Appendix A: Disease-Specific Chapters: Cryptosporidiosis. Toronto: Queen’s Printer for Ontario; 2015. Available from Retrieved from