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Cryptosporidium, organism
Cryptosporidium, organism

Digestive system organs
Digestive system organs


Cryptosporidium enteritis is an infection of the small intestine that is caused by the parasite cryptosporidium. The main symptom is diarrhea.

Alternative Names:


Causes, incidence, and risk factors:

Cryptosporidium has recently been recognized as a worldwide cause of diarrhea in all age groups. Its major impact has been among those with weakened immune systems, including:

  • People who take medications to suppress their immune system
  • People with HIV or AIDS
  • Transplant recipients

In these groups, this diarrheal infection is not just bothersome. It also can lead to severe, and potentially life-threatening, loss of muscle and body mass (wasting) and malnutrition.

The major risk factor is swallowing water contaminated with fecal matter. Those at higher risk include:

  • Animal handlers
  • Men who have sex with men
  • People in close contact with infected individuals
  • Young children

Outbreaks have been linked to:

  • Drinking from contaminated public water supplies
  • Drinking unpasteurized cider
  • Swimming in contaminated pools and lakes

  • Abdominal cramping
  • Malaise
  • Malnutrition and weight loss (in severe cases)
  • Nausea
  • Watery diarrhea, usually large-volume and multiple times a day

Signs and tests:
  • Antibody test to see if cryptosporidium are in the stool
  • Intestinal biopsy (rare)
  • Special staining of the stool (called AFB staining)
  • Stool ova and parasites exam using a microsope


There is no one treatment for cryptosporidium enteritis.

Drugs such as nitazoxanide have been used in children and adults. Other drugs that are sometimes used include:

  • Paromomycin
  • Trimethoprim-sulfamethoxazole
  • Metronidazole
  • Atovaquone
  • Azithromycin are sometimes used

However, these drugs usually only help for a little while.

Right now, the best approach is to improve the immune status in people who have a weakened immune system. This can be done, for example, by using highly active antiviral therapy in people with AIDS.

AIDS specialists and patient activists may provide additional information on the latest treatments, and on medications and alternative treatments that may provide some relief.

Support Groups:

Expectations (prognosis):

In healthy people, the infection will clear up but can last up to a month. In people who are immunosuppressed , prolonged diarrhea may cause loss of body weight and malnutrition.

  • Cholangitis (inflammation of a bile duct), cholecystitis (inflammation of the gallbladder)
  • Hepatitis
  • Pancreatitis
  • Severe malabsorption (not enough nutrients being absorbed from the intestinal tract)
  • Wasting syndrome (loss of body mass where the person becomes very thin and weak)

Calling your health care provider:

Notify your health care provider if you develop watery diarrhea that does not go away within a few days, especially if you are immunosuppressed.


Proper sanitation and hygiene, including handwashing, are important measures in the prevention of this illness.

Certain water filters can also reduce risk by filtering out the eggs of the cryptosporidium organism. However, the pores of the filter must be smaller than 1 micron to be effective. If you are immunosuppressed, ask your doctor if you need to boil your water.


Montes M, DuPont HL. Enteritis, enterocolitis and infectious diarrhea syndromes. In: Cohen J, Powderly WG, Berkley SF, et al., eds. Infectious Diseases. 2nd ed. Philadelphia, PA: Mosby Elsevier; 2004:chap 43.

Kirkpatrick BD, Sears CL. Cryptosporidiosis. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, PA: Saunders Elsevier; 2007:chap 371.

Review Date: 5/19/2008
Reviewed By: Sean O. Stitham, MD, private practice in Internal Medicine, Seattle, WA; Jatin M. Vyas, MD, PhD, Instructor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Massachusetts General Hospital. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

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789 Central Avenue, Dover, NH 03820
Phone: (603) 742-5252
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