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Test Catalog

Test ID: CRYPS    
Cryptosporidium Antigen, Feces

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

Establishing the diagnosis of intestinal cryptosporidiosis

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

For other diagnostic tests that may be of value in evaluating patients with diarrhea; the following algorithms are available in Special Instructions:

-Parasitic Investigation of Stool Specimens Algorithm

-Laboratory Testing for Infectious Causes of Diarrhea

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

Cryptosporidia are small apicomplexan protozoan parasites that infect the intestinal tract of humans and animals. They were conventionally categorized as coccidia, but are now known to be more closely related to the gregarines. Many species may infect humans, with the most common being Cryptosporidium hominis and C parvum. Infected humans and animals shed small (4-6 micrometer in diameter) infectious oocysts in their stool, and these can subsequently contaminate and survive in recreational and drinking water supplies.

 

Infection of humans occurs by the fecal-oral route or via ingestion of contaminated water or food. Infection is easily acquired, with an infectious dose of approximately 100 oocysts. Waterborne transmission is a primary mode of transmission and is commonly responsible for human outbreaks. This is due to the fact that Cryptosporidium species oocysts are resistant to cold temperatures and chlorine, and require extensive filtration or water treatment to remove them from drinking water.

 

The incubation period is typically 7 to 10 days following exposure. While most patients have symptoms, approximately 30% of infected individuals are asymptomatic. When symptoms are present, they usually include profuse watery diarrhea, malaise, anorexia, nausea, crampy abdominal pain, and low grade fever. Infection is usually self-limited in immunocompetent individuals, with resolution of symptoms in 10 to 14 days. However, diarrhea can be prolonged and life-threatening in immunocompromised patients such as those with AIDS, infants, and the elderly, and result in severe dehydration and wasting.

 

The fecal ova and parasite examination is an insensitive method for detecting Cryptosporidium, given the small size of the oocysts and their lack of trichrome staining. Instead, use of the Cryptosporidium antigen test (CRYPS / Cryptosporidium Antigen, Feces) or the multiplex gastrointestinal PCR panel (GIP / Gastrointestinal Pathogen Panel, PCR, Feces) is recommended for sensitive and specific detection. The antigen test is ideal for situations in which cryptosporidiosis is highly suspected (eg outbreak scenarios), whereas the PCR panel allows for simultaneous detection of multiple parasitic, viral, and bacterial causes of diarrhea.

 

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

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.

Negative

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 at least two fecal specimens may be required to detect Cryptosporidium using antigen testing.

Clinical Reference Recommendations for in-depth reading of a clinical nature

Centers for Disease Control and Prevention: Parasites-Cryptosporidium (also known as "Crypto"). Accessed 10/16/2019. Available at www.cdc.gov/parasites/crypto/index.html

Special Instructions Library of PDFs including pertinent information and forms related to the test