Discussion:

Cryptosporidium is a zoonotic Acid-Fast protozoa. The most common species found in humans are C. parvum and C. hominis but infections by C. felis, C. meleagridis, C. canis, and C. muris have also been reported.

Cryptosporidiosis usually causes a mild self-limiting diarrhea in immunocompetent people. However, in the immunocompromised patient, infection may result in chronic profuse watery diarrhea, resulting in weight loss and dehydration.

Transmission of Cryptosporidium is usually fecal-oral through contaminated water. The infected host excretes the sporulated oocysts which are then ingested. Sporozoites are released in the small intestine where they parasitize the cells, become trophozoites and undergo both asexual and sexual multiplication. After fertilization, oocysts are formed and excreted into the environment. The oocysts are infective immediately after excretion. Contamination of the environment or auto-infection can occur.

Sexual transmission can occur as well.

Diagnosis is typically made by identification of acid-fast oocysts in the stool. Shedding may be intermittent – 3 stool specimens collected on separate days before considering the test results negative. Polymerase chain reaction assays may be used to determine species.

Small intestine biopsies show 2 – 5 microns basophilic bodies and may be mistaken for cellular debris. Despite its appearance, the parasite is an intracellular organism located in an extracytoplasmic vacuole at the luminal surface of the cell.

Treatment – mainly supportive.

Several cryptosporidiosis outbreaks have been reported with the most recent being in central Ohio, resulting in the closure of many recreational parks and community pools.