Test Catalog

Interpretive Handbook

Test 80335 :
Cryptosporidium Antigen, Feces

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Cryptosporidia are protozoa of the coccidian group which are common parasites of livestock animals and can contaminate and survive in surface water supplies.


Infection of humans occurs by the fecal-oral route or by ingestion of contaminated water. The exact mechanism by which the organism causes gastroenteritis is unknown.


Cryptosporidiosis occurs as a profuse diarrhea in patients with AIDS and as a self-limited moderate diarrhea in young children, especially daycare attendees and their relatives.


See Parasitic Investigation of Stool Specimens Algorithm and Laboratory Testing for Infectious Causes of Diarrhea in Special Instructions for other diagnostic tests that may be of value in evaluating patients with diarrhea.

Useful For Suggests clinical disorders or settings where the test may be helpful

Establishing the diagnosis of intestinal cryptosporidiosis

Interpretation Provides information to assist in interpretation of the test results

A positive enzyme-linked immunosorbent assay (ELISA) indicates the presence of antigens of cryptosporidium and is interpreted as evidence of infection with that organism.


The sensitivity, specificity, and positive predictive value of the ELISA were 87%, 99%, and 98% respectively, as determined by examination of 231 fecal specimens by conventional microscopy and by ELISA.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Examination of multiple fecal specimens may be required to detect Cryptosporidium.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.


Clinical References Provides recommendations for further in-depth reading of a clinical nature

Soave R, Johnson WD Jr: Cryptosporidium and Isospora belli. J Infect Dis 1988;157:225-229

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