Arabian foal running in field

What is Cryptosporidiosis?

Parasites in the genus Cryptosporidium are an important source of gastrointestinal disease in humans and animals globally. These highly contagious parasites infect the intestine and cause diarrhea and weight loss. Cryptosporidiosis, associated specifically with Cryptosporidium parvum, is most commonly seen in foals one to four weeks of age. Foals that are immunocompromised (especially those with severe combined immunodeficiency syndrome) or stressed are particularly at risk of infection. Foals become infected by ingesting the parasite (in the oocyst stage) in contaminated food or water.

The parasite can be transmitted from horses to humans in contaminated water, soil, or surfaces and can survive in the environment for long periods.

What are the clinical signs of Cryptosporidiosis?

Diarrhea, dehydration, and weight loss are clinical signs of Cryptosporidiosis in foals.

Subclinical infection may be common in adult horses and foals that otherwise appear healthy.

How is Cryptosporidiosis diagnosed?

Cryptosporidiosis is diagnosed by identification of Cryptosporidium oocysts in fecal samples by staining, immunofluorescence assay, or flow cytometry. The parasite can also be identified by enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR).

How is Cryptosporidiosis treated?

There is no specific treatment, including antibiotics, for Cryptosporidiosis. Therapy for sick foals is largely supportive, often involving fluid replacement.

What is the prognosis for Cryptosporidiosis?

Many horses recover fully, but Cryptosporidiosis can be fatal if left untreated. The disease is serious in immunocompromised foals.

How can Cryptosporidiosis be prevented?

Cryptosporidiosis can be challenging to prevent and control. There are no vaccines currently available for Cryptosporidiosis. Oocysts shed in feces are very hardy and can survive for extended periods in the environment. They are also resistant to many disinfectants.

Good biosecurity protocols, including isolation of infected foals and disinfection of contaminated areas, are the best ways to prevent Cryptosporidiosis.

For more information

UC Davis School of Veterinary Medicine PCR Laboratory

Diseases with horse to human transmission, UC Davis Center for Equine Health

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