(Protozoan) Cryptosporidium parvum
a.k.a "crypto"

Edward Tyzzer

Cryptosporidiosis was first recognized in 1907 by Edward Tyzzer in the gastric glands of asymptomatic laboratory mice. For nearly 50 years after Tyzzer's initial discovery the protozoan was considered a benign commensal organism. It was not until 1955, when Cryptosporidiosis was discovered in fowl with fatal enteritis that the protozoan was considered a parasite. Since the 1970s, Cryptosporidiosis has been identified in the gastrointestinal or respiratory tract of most species of animals, including mammals, reptiles, birds and fish. Cryptosporidiosis has now entered the forefront of public attention as it has become a lethal threat to immunosuppressed individuals. In the case of HIV, cryptosporidiosis plays the role of an opportunistic infection as it may cause severe dehydration and malnutrition, which may be fatal to the HIV positive patient.


The symptoms of a Cryptosporidia infection are diarrhea, abdominal pain, weight loss, slight fever and nausea. These symptoms usually manifest themselves in the individual within 2-10 days of exposure to the parasite.


Cryptosporidiosis has a large reservoir, which includes cattle, deer, mice, dogs, cats, and poultry. Cryptosporidia live in the intestine of infected humans or animals. These parasites are passed on through contact with infected feces or through contact with contaminated water, food, soil. There is no documented animal vector for this parasite.


The diagnosis of cryptosporidiosis is performed through two methods: intestinal biopsy or examination of stool samples to detect the oocysts.


The usual method of therapy is to allow the infection to run its course. The patient is encouraged to ingest a lot of water in order to combat the effects of diarrhea. The parasitic infection usually disappears from the body of a healthy adult within at most 2 weeks. In the case of immunosuppressed individuals, pregnant women and young children, there are several courses of therapy to speed up the recovery process. The drugs paromomycin, azythromycin and nitazoxonide are used as treatments, even though their efficacy rates have not been impressive.


Contact with human and animal feces should be entirely avoided and if such interaction is necessary as in diaper changing, litter box cleaning, the individual should wear protective gloves. If contact occurs the individual should immediately wash and disinfect exposed area. Ingestion of water from rivers, lakes, swimming pools or other such open bodies of water should be avoided. Water used for drinking should be filtered or boiled for at least 1 minute.


Tyzzer Biography
Crypto Illustration
Crypto Fact Sheet
Basic Biology of Crypto


Bartlett, John G., Blacklow, Neil R. Gorbach, Sherwood L., Infectious Disease. W.B. Saunders Company: Philadelphia, 1998.

Bennett, John E., Dolin, Raphael, Mandell, Gerald, L. Principles and practice of infectious diseases. Churchill Livingstone: Philadelphia, 2000

Hoperich, Paul D., Jordan, M. Colin, Ronald, Allan R. Infectious Diseases: A Treatise of Infectious Processes. J.B Lippincott Company: Philadelphia, 1994.

John, David T., Krotoski, Wojciech A., Markell, Edward K. Markell and Voge's Medical Parasitology. W.B. Saunders Company: New York, 1999.

Petry, Franz. Cryptosporidiosis and microsporidiosis. Basel: New York, 2000.