Cryptosporidiosis is an infection of the intestine. It can cause severe diarrhea .

Most healthy adults recover from this infection in a few weeks. It can be life threatening for young children, the elderly, and very sick people.

The Intestines

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It is caused by a parasite called Cryptosporidium parvum . These parasites live in the intestines of infected people and animals. They can also contaminate objects and surfaces that people touch. They may also be in soil where food is grown. The parasite can also be in recreational waters where people swim.

The infection is caused by swallowing the parasite. When the parasite enters your intestine, it comes out of its shell. It will multiply and may cause an infection. Eventually, it is passed from your body through a bowel movement.

Some sources of cryptosporidiosis are:

  • Humans and animals:
    • Contact with diapers or clothing that are contaminated with the infection
    • Contact with animal feces by touching animals, cleaning cages, or visiting barns
    • Sexual activity that involves contact with feces
  • Food:
    • Eating food grown in, or contaminated by, infected soil
    • Drinking unpasteurized milk, dairy products, or apple juice
    • Eating food that was handled by someone who is infected or washed in contaminated water
  • Water:
    • Accidentally swallowing water in contaminated recreational water, such as a lake, ocean, bay, stream, hot tub, swimming pool, or water park
    • Drinking water or ice that is contaminated

Risk Factors

People who are at increased risk for cryptosporidiosis 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
  • International travelers, backpackers, hikers, and campers


Symptoms usually begin about a week after infection. Some people will not have any.

Symptoms consist mainly of:

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

The symptoms may come and go before you are finally better.


Your doctor will take one or more stool samples. They will be sent to a lab to be examined.


People with healthy immune systems usually recover without needing treatment. Recovery can take several weeks. It may take up to one month. If you have severe diarrhea, you may be given:

  • IV fluids
  • Antidiarrheal drugs
  • Nitazoxanide —a drug recently approved to treat the diarrhea associated with cryptosporidiosis in healthy people

People with a weakened immune system have a greater risk of getting this infection. People with AIDS have this higher risk. They are also likely to have a more severe and longer infection. They may become permanently infected.


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

  • Wash your hands:
    • 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, it’s important to avoid spreading the parasite to others by:
  • Washing your hands frequently
  • Not swimming in recreational waters
  • Taking precautions during sexual activity