Cryptosporidiosis - Causes, Symptoms, Diagnosis and Treatment

What is cryptosporidiosis?

Cryptosporidiosis is a diarrheal infection caused by the parasite Cryptosporidium. The parasite is transmitted after drinking or swallowing contaminated food or water, including water swallowed while swimming. Because the parasite is protected by an outer shell that allows it to survive for long periods of time outside the body, it is very resistant to chlorine disinfection.

Where does cryptosporidiosis occur?

Cryptosporidium is prevalent throughout the world. Travelers to developing countries who visit rural areas, hike or trek in backcountry areas, or frequently eat or drink in areas where sanitation is poor are at greatest risk of contracting the disease. Outbreaks of cryptosporidiosis have also occurred in the United States when water supplies or swimming pools become contaminated.

How is cryptosporidiosis spread?

The disease is spread by accidentally swallowing anything that has come into contact with the feces of a person or animal with the infection. This includes:

  • Swallowing water contaminated with cryptosporidiosis. The infectious stage of the parasite, called an oocyst, can be transmitted by swallowing water from swimming pools, hot tubs, jacuzzis, lakes, rivers, springs, ponds, or streams contaminated with sewage or feces (from either humans or animals).

  • Eating uncooked foods contaminated with the parasite.

  • Swallowing the parasite picked up from surfaces contaminated with the stool of an infected person. This includes bathroom fixtures, changing tables, and diaper pails.

Who is at risk for cryptosporidiosis?

While cryptosporidiosis is normally not a serious disease, for persons with a severely weakened immune system, it can lead to a serious or life-threatening illness. This includes persons with:


  • Cancer and transplant patients who are taking certain immunosuppressive drugs

  • Inherited diseases that affect the immune system

What are the symptoms of cryptosporidiosis?

The following are the most common symptoms of cryptosporidiosis. However, each individual may experience symptoms differently. Symptoms may include:

  • Diarrhea

  • Loose or watery stools

  • Stomach cramps

  • A slight fever

Some persons do not present any symptoms. If symptoms are present, they often last about two weeks and then you may feel better. However, you continue to pass the parasite in your stool for up to two months, and during this period you may spread the infection to others.

How can cryptosporidiosis be prevented?

The best ways to prevent cryptosporidiosis are through good personal hygiene, avoiding unsafe water sources, and avoiding unboiled water and uncooked foods in areas known to have poor sanitation.

  • Wash hands thoroughly with soap and water after using the toilet or changing diapers.

  • Wash hands thoroughly before eating or preparing food.

  • Wash and peel all raw fruits and vegetables before eating.

  • Avoid drinking water from lakes, rivers, springs, ponds, or streams, unless they have been filtered and chemically treated.

  • Avoid any water or food that may be contaminated.

  • When traveling to countries where the water supply may be unsafe, avoid drinking unboiled tap water and avoid eating any raw foods washed with tap water. Choose steaming hot drinks, such as coffee and tea, and pasteurized fruit drinks. If choosing bottled water, make sure it is bottled water that is safe to drink.

How is cryptosporidiosis diagnosed?

Diagnosis of cryptosporidiosis is made through examination of stool samples to determine if they are infected. Because tests for this disease are not routinely done in laboratories, special testing for the parasite must be done.

Treatment for cryptosporidiosis

There is no completely effective treatment for cryptosporidiosis, and persons with a healthy immune system generally recover on their own. Persons who are in poor health or those persons with a weakened immune system risk a more serious infection. Fluid replacement is important (as with any diarrheal disease) and some medications may help to alleviate diarrhea symptoms. Specific treatment for cryptosporidiosis will be determined by your doctor based on:

  • Your overall health and medical history

  • Extent of the disease

  • Your tolerance for specific medications, procedures, or therapies

  • Expectations for the course of the disease

  • Your opinion or preference