Cryptosporidiosis is an intestinal infection. It can cause severe diarrhea in some people.

Most healthy adults recover from this infection in a few weeks. However, it can be life threatening for young children, the elderly, and the people who are sick. Cryptosporidiosis can be especially difficult in those with compromised immune systems.

The Intestines
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Cryptosporidiosis is an infection caused by a parasite. The parasite enters the body by being swallowed. Once in the intestine, the parasite comes out of its shell and multiplies. You can come in contact with the parasite through:

  • Contaminated water (the most common way for the parasite to be transmitted):
    • Accidentally swallowing water in contaminated recreational water such as lakes, streams, hot tubs, swimming pools, or water parks
    • Drinking water or ice that is contaminated
  • Contact with contaminated diapers or clothing
  • Contact with contaminated animal feces by touching animals, cleaning cages, or visiting barns or petting zoos
  • Sexual activity that includes contact with contaminated feces
  • Eating food grown in, or contaminated by, infected soil
  • Drinking contaminated, unpasteurized milk, dairy products, or juice
  • Eating food that was handled by someone who is infected or food that was washed in contaminated water

Risk Factors

People who have a higher risk of cryptosporidiosis infection include:

  • Young children, especially if they are in day care
  • Day care workers or those who work in a group setting
  • People whose immune system is weakened by cancer, AIDS, or an organ transplant
  • People who engage in oral-anal sex
  • Backpackers, hikers, and campers who may come into contact with contaminated water sources


Most of the time, exposed people will not have symptoms. Symptoms that do occur usually begin about a week after the infection and may include:

  • Watery diarrhea
  • Stomach cramps
  • Upset stomach, vomiting
  • Slight fever
  • Weakness
  • Weight loss
  • Dehydration


Your doctor will ask about your symptoms and medical history. You will be asked for one or more stool samples. The samples will be sent to a lab to look for the parasite.


Most of the time your body will get rid of this infection on its own. People with healthy immune systems usually recover without needing treatment. People with a weakened immune system, like those with AIDS, have a greater risk of getting this infection. The infection is also more likely to be more severe and last longer.

Recovery can take several weeks. If you have severe diarrhea, you may be given:

  • IV fluids
  • Antidiarrheal drugs
  • Nitazoxanide—this drug may not work if the immune system is weak


There are several important measures you can take to lower your risk of cryptosporidiosis:

  • Wash your hands often, especially:
    • After using the toilet
    • After changing a diaper
    • Before handling or eating food
    • After contact with animals or soil
    • After contact with infected people
  • Drink safe water. Boil water if you are unsure if it’s safe.
  • Avoid swallowing water when swimming in recreational water.
  • Eat safe food. Wash vegetables that will be eaten raw.
  • Drink only pasteurized milk and juice.
  • Use precautions during sexual activity.

If you are infected with cryptosporidiosis, avoid spreading the infection to others by:

  • Washing your hands frequently.
  • Avoiding swimming in recreational waters.
  • Taking precautions during sexual activity.

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