Cryptosporidiosis: what you need to know

Cryptosporidiosis: what you need to know

Cryptosporidiosis is a parasitic infection of the small intestine. Diarrhea is the main symptom, but in immunologically-impaired individuals, such as patients with HIV or AIDS, the symptoms can be severe or even fatal.

Cryptosporidiosis tends to be an acute short-term infection. It spreads through the fecal-oral route, often through contaminated water. It is also known as crypto.

In the United States (U.S.) there are an estimated 748,000 annual cases of cryptosporidiosis, but over 98 percent of cases go unreported.

Signs and symptoms

Cryptosporidiosis causes gastric issues including watery diarrhea.

In people with a healthy immune system, the main symptom is self-limiting diarrhea.

Symptoms appear from 1 to 12 days after infection, with an average of 7 days. They last for up to 2 weeks or, in some cases, up to a month.

In a person with a healthy immune system, there may be:

  • no noticeable symptoms
  • acute diarrhea
  • persistent diarrhea that can last for a few weeks

Diarrhea is usually watery with mucus. Rarely, there may be blood or leukocytes in the diarrhea.

The person may also have stomach pains or cramps and a low fever.

Other symptoms include:

  • nausea
  • vomiting
  • malabsorption
  • dehydration

A carrier of cryptosporidiosis who does not show symptoms can still pass on the infection to others.

Even after symptoms have gone, an individual remains infective for some weeks.


Cryptosporidiosis is caused by the parasite cryptosporidium.

Many species of cryptosporidium can infect humans and a wide range of animals.

The appearance of cryptosporidium in the gut.

Image credit: Alae-eddine GATI, 1987

The parasite is protected by an outer shell that allows it to survive outside the body for hours and makes it resistant to chlorine disinfection.

Infection happens through contaminated material such as earth, water, and uncooked or cross-contaminated food that has been in contact with the feces of an infected individual or animal.

Millions of crypto organisms, or oocysts, can be released in the bowel movement of an infected human or animal. Infection happens after accidentally ingesting the oocysts.

It is prevalent amongst those who are in regular contact with fresh water, including swimming pools.

A person can get crypto by putting anything in the mouth that has touched the feces of an infected person or animal. Some outbreaks have happened in day care centers, as a result of diaper changes.

It is not spread by contact with blood.

Cryptosporidiosis is responsible for 50.8 percent of water-borne diseases that are attributed to parasites.

In developing countries, 8 to 19 percent of diarrheal diseases can be attributed to cryptosporidium.

The high resistance of cryptosporidium oocysts to disinfectants such as chlorine bleach enables them to survive for long periods and remain infective outside of a host body.


To diagnose crypto, a physician may first observe the initial symptoms after an incubation period of 1 to 12 days.

Next, a stool sample will be tested in a laboratory. The stool culture can reveal the presence of the parasite and it can help to rule out other pathogens.

A pathogen is another name for a bacterium, virus, or microorganism that can cause disease.

Antigen-detection assays can confirm a diagnosis. Antigens are the toxic or foreign substances in the body that trigger an immune response.

Other tests include:

  • an enzyme-linked immunosorbent assay
  • an immunochromatographic assay
  • an immunofluorescent assay

A physician may use an ultrasound to check for crypto in the bile system. There may be dilated or irregular bile ducts and a thickened gallbladder.

Finally, an Endoscopic Retrograde Cholangiopancreatography (ERCP) may confirm the diagnosis.

An ERCP involves the insertion of a flexible, lighted tube through the mouth and into the stomach and small intestine.


There are several treatment and management options for crypto.

Anti-diarrheal drugs, such as nitazoxanide, can treat patients of all ages. Eighty percent of symptoms resolve in under 5 days with this drug.

Swimming is not recommended for at least 2 weeks following a recovery from crypto.

It is common for the infection to return.

Activities such as swimming are not recommended for at least 2 weeks after symptoms have gone.

People who have, or who have recently had, cryptosporidiosis should not swim in communal areas. This is because the pathogen can spread from the anal and genital areas. The oocysts continue to shed for some time.

A lactose-free diet can help to soothe the digestive tract and reduce inflammation.

It is important to keep hydrated. A person with severe dehydration may need intravenous fluids.

Antibiotics are not usually helpful and are primarily reserved for persons with a severe presentation of the disease and a weak immune system.

Crypto in patients with a weakened immune system

A person with HIV or AIDS has a higher risk of catching cryptosporidiosis, because their immune system is compromised and their body cannot fight infection effectively.

Antiviral treatment can enhance the immune system and increase resistance to a range of infections.

Studies have suggested that drugs such as rifabutin and clarithromycin, when taken for Mycobacterium avium (M. avium) complex prophylaxis, may protect against crypto.

If a person with HIV or AIDS has crypto, they are more likely to need active intervention to resolve it than people with a healthy immune system.

They will need to be monitored for volume depletion and electrolyte imbalance, resulting from dehydration, and for weight loss and malnutrition.


The best way for people to prevent cryptosporidiosis is to follow the guidelines for hygiene and sanitation.

Washing of the hands before and after eating and upholding good hygiene are the most effective ways to keep cryptosporidiosis at bay.

This includes washing the hands carefully before eating and after using the bathroom or any potential contact with stool.

People should avoid contact with animal feces and potentially contaminated food and water.

It is important to wash and cook vegetables thoroughly at all times.

When camping or traveling, people should use bottled water or boil or filter their water, and avoid drinks containing ice.

Another means of protection is to refrain from refrain from sexual activities that involve exposure to feces.

People with a compromised immune system should take extra care to protect themselves from water in lakes and streams.

Cryptosporidium: What You Should Know (Video Medical And Professional 2020).

Section Issues On Medicine: Disease