Cryptosporidium

Cryptosporidium

Cryptosporidium is a microscopic parasite that causes the diarrhoeal disease cryptosporidiosis. Both the parasite and the disease are commonly known as “Crypto.”

The parasite is protected by an outer shell (oocyst)

Allows survival outside the body for long periods of time 

Very tolerant to chlorine disinfection.

Water is the most common form of spread

Poses serious risk to immunocompromised individuals, eg AIDS; cancer and transplant patients who are taking certain immunosuppressive drugs. 

Symptoms

Symptoms of cryptosporidiosis generally begin 2 to 10 days (average 7 days) after infection. 

Watery diarrhea

Stomach cramps or pain

Dehydration

Nausea

Vomiting

Fever

Weight loss

Some people with Crypto will have no symptoms at all.

Symptoms usually last about 1 to 2 weeks (with a range of a few days to 4 or more weeks) in persons with healthy immune systems. Occasionally, people may experience a recurrence of symptoms after a brief period of recovery before the illness ends. Symptoms can come and go for up to 30 days.

In immunocompromised persons Cryptosporidium infections could possibly affect other areas of the digestive tract or the respiratory tract.

Diagnosis & Detection

Cryptosporidium oocysts in a modified acid-fast stain. (CDC Photo; DPDx)

Examination of stool samples. 

Detection can be difficult - several stool samples over several days.

acid-fast staining, direct fluorescent antibody [DFA] , and/or enzyme immunoassays 

Molecular methods (e.g., polymerase chain reaction – PCR) are increasingly used in reference diagnostic labs,

Treatment

Most people who have healthy immune systems will recover without treatment. Young children and pregnant women may be more susceptible to dehydration resulting from diarrhoea. 

For those persons with AIDS, anti-retroviral therapy (improves the immune status) will also decrease or eliminate symptoms of cryptosporidiosis. However, even if symptoms disappear, cryptosporidiosis is often not curable and the symptoms may return if the immune status worsens.

Cryptosporidium and AIDS

Advanced immunosuppression — typically CD4 T lymphocyte cell (CD4) counts of <100 cells/µL — is associated with the greatest risk for prolonged, severe, or extraintestinal cryptosporidiosis. 

The three species that most commonly infect humans are Cryptosporidium hominis, Cryptosporidium parvum, and Cryptosporidium meleagridis. Infections are usually caused by one species, but a mixed infection is possible.

Up to 74% of diarrhoea stools in AIDS patients demonstrating the organism in less developed countries where potent antiretroviral therapy  is not widely available, 

cryptosporidiosis has decreased and occurs at an incidence of <1 case per 1000 person-years in patients with AIDS.4 Infection occurs through ingestion of Cryptosporidium oocysts. Viable oocysts in feces can be transmitted directly through contact with infected humans or animals, particularly those with diarrhea. Oocysts can contaminate recreational water sources such as swimming pools and lakes, and public water supplies and may persist despite standard chlorination (see Appendix: Food and Water-Related Exposures). Person-to-person transmission is common, especially among sexually active men who have sex with men.

Fever is present in approximately one-third of patients and malabsorption is common. 

The epithelium of the biliary tract and the pancreatic duct can be infected with Cryptosporidium, leading to sclerosing cholangitis and to pancreatitis secondary to papillary stenosis, 

Pulmonary infections also have been reported, and may be under-recognized.

Treatment 

ART with immune restoration to a CD4 count >100 cells/µL usually leads to resolution

Treatment of diarrhoea with anti-motility agents (AIII) may be necessary. 

Patients with biliary tract involvement may require endoscopic retrograde choledocoduodenoscopy for diagnosis. 

Immune reconstitution inflammatory syndrome (IRIS) has not been described in association with treatment of cryptosporidiosis.

No pharmacologic interventions are known to be effective in preventing the recurrence of cryptosporidiosis.

No therapy has been shown to be effective without ART.