Cryptosporidiosis, or “crypto” for short, is a disease caused by a group of organisms called Cryptosporidium. The organisms infect the lining of the small intestine and can cause severe diarrhea and malabsorption (an inability to absorb nutrients).


Cryptosporidium is spread by feces. Food or water contaminated with animal feces may carry these organisms; it’s also possible that oral-anal sex may spread the infection. On occasion, there are outbreaks of cryptosporidiosis that can be traced to a feces-contaminated water supply. This is most common in warm-weather climates.

While anybody exposed to Cryptosporidium can get sick from it, diarrhea and malabsorption is usually limited to a few days in people with healthy immune systems. People with compromised immune systems—usually people with a CD4 cell count below 100—may experience prolonged and severe bouts of diarrhea and malabsorption that can be difficult to treat. In rare cases, the infection can cause pancreatitis or lung infections.

What are the symptoms, and how is it diagnosed?

Watery diarrhea is a primary symptom of crypto, along with abdominal pain, nausea, vomiting, cramping of the lower abdomen, weight loss, loss of appetite, dehydration, and passing gas (flatulence).

Most cases of crypto can be diagnosed using a stool sample. To do so, the stool is stained with a dye and examined under a microscope. Another way to diagnose crypto is by endoscopy or colonoscopy. These procedures use thin, long cameras inserted down the throat or through the anus to examine the small (and large) intestine. Samples of intestinal tissue are collected and examined in a lab.

How is it treated or prevented?

The best treatment for crypto appears to be antiretroviral (ARV) drugs used to treat HIV. By treating HIV effectively, it’s possible to increase CD4 cell counts to levels above 100. In many cases, this has been proven to work well for many HIV-positive people with crypto. Unfortunately, crypto can cause malabsorption and may decrease the level of HIV drugs that reach the bloodstream, so people should be monitored closely until their diarrhea has resolved. Antibiotics to treat crypto directly may also be used, but do not work consistently unless they are combined with ARV HIV treatment. It is also important with crypto to guard against dehydration—oral rehydration solutions that include important electrolytes should be used aggressively.

There are actually three different approaches that can be taken when treating crypto: to treat the infection, slow the diarrhea, and correct the weight loss.

One antibiotic, nitazoxanide (Alinia), has been approved for children and adults with crypto, at a dose ranging from 500 to 1,000 mg taken twice a day for 14 days.

Another antibiotic, paromomycin (Humatin), at a doses between 1500 mg and 2000 mg a day, has been shown to both cure the infection or greatly reduce diarrhea associated with the infection. Paromomycin is approved for sale in the United States, albeit not for crypto. In other words, a doctor can still prescribe it, but cryptosporidiosis will not be listed in the package insert.

To help control the diarrhea, perhaps in combination with antibiotic therapy, a number of anti-diarrheal drugs can be taken. These include: Lomotil, loperamide (Imodium), paregoric, tincture of opium and Pepto-Bismol. A medication used to stop tumor-induced diarrhea, octreotide (Sandostatin), is no more effective than Lomotil, Imodium and other such remedies, so it is not highly recommended. And because diarrhea is the direct result of intestinal inflammation caused by the infection, some non-steroidal anti-inflammatory drugs (NSAIDS) may be helpful such as ibuprofen (e.g., Advil).

In the event of weight loss, it might be necessary to treat people with crypto using nutritional supplementation. Unfortunately, many nutritional supplements that can be taken by mouth aren’t absorbed properly, thus requiring nutritional supplementation through an intravenous (IV) line. This is called total parenteral nutrition (TPN) and, despite its high cost, it can be very effective in providing the body with the nutrients it needs.

Some anabolic agents, such as human growth hormone (Serostim) and anabolic steroids (e.g., Deca-Durabolin, Oxandrin, Winstrol), can be useful in preventing—and perhaps reversing—muscle loss that often occurs in people with weight-reducing infections like crypto.

A syndrome—called immune reconstitution inflammatory syndrome (IRIS)—where antiretroviral treatment can actually exacerbate the symptoms of an opportunistic infection due to a strengthened immune response, has not been reported with crypto.

The most effective way to prevent crypto is to avoid its sources—mainly contaminated drinking water and handling feces from pets and small children. HIV-positive people with severely compromised immune systems are often encouraged to drink bottled or boiled water and not use ice made from unfiltered tap water. It’s also best to peel fruits and vegetables and/or wash them thoroughly in boiled water. Washing hands frequently is very important, especially when changing diapers or helping small children use the bathroom or in cleaning litter boxes or picking up after dogs. People with compromised immune systems may also need to avoid eating raw oysters.

Are there any experimental treatments?

If you would like to find out if you are eligible for any clinical trials that include new therapies for the treatment or prevention of crypto, visit, a site run by the U.S. National Institutes of Health. The site has information about all HIV-related clinical studies in the United States. For more info, you can call their toll-free number at 1-800-HIV-0440 (1-800-448-0440) or email

Last Reviewed: January 18, 2016