Cryptosporidiosis is a disease caused by intracellular protozoan parasite Cryptosporidium 

At risk populations: day-care settings, travelers, backpackers, campers, swimmers

-After ingestion, oocysts excyst within the intestine and form trophozoites which cause diarrhea

-Trophozoites do not invade the intestine; the site most heavily infested is jejunum 

-Purification of water supply: Cysts are highly resistant to chlorination; they are killed by pasteurization; can be removed by filtration 

Symptoms & Signs 

Immunocompetent patients: self-limited watery diarrhea, dehydration, nausea, and vomiting 

Immunocompromised patients: Chronic watery, nonbloody diarrhea, fever, dehydration and weight loss 

Biliary tree involvement: cholangitis, hepatitis, and pancreatitis 


-At least 3 different stool samples should be inspected for oocysts 

-Acid-fast stains reveal red cysts on a blue background 


-Nitazoxanide: effective for immunocompetent patients but not for HIV-infected patients 

-Antiretroviral therapy can alleviate symptoms in the latter