Ova & Parasite Examination from Stool Specimens

The most common stool parasite found in New Mexico is Giardia, followed by Cryptosporidia. These pathogens can be detected with high sensitivity with EIA tests.
 

When the EIA test is employed, testing a single stool will detect most infections caused by Giardia or Cryptosporidia. If the patient is immunocompetent, has no foreign travel history and is not a recent immigrant or visitor from an endemic area that has amoebae or other parasites, the EIA test for either Giardia or Cryptosporidia should be sufficient. The test(s) can be ordered by selecting Giardia Antigen (test code GEIA), Cryptosporidium Antigen (test code CEIA), or both Giardia and Cryptosporidium Antigens (test code OPEIA). The Ova & Parasite (Microscopic Exam), test code OP, should also be ordered if parasitic infection is still a possibility and the patient either 1) has traveled to a location where amoebae are common, 2) is immunocompromised for any reason, including HIV or 3) continues to have symptoms that cannot be explained by other conditions. When ordering this test, you will need to indicate on the requisition the pertinent travel history and/or immune status of the patient.
 

Parasites such as Entamoeba histolytica must be detected by microscopic concentration [Ova & Parasite (Microscopic Exam)], test code OP. If the first microscopic examination is negative and the patient is still exhibiting symptoms, a second, and possibly a third, stool specimen should be collected and tested using the same method.
 

Most infections do not require a third stool for examination. If the EIA tests and/or the microscopic exams are negative and the patient continues to exhibit symptoms, special procedures may be required to test for unusual parasites such as Microsporidium (usually found only in severely immunosuppressed patients, such as AIDS patients). Cyclospora is a relatively unusual cause of diarrhea that is foodborne and appears to be imported into the United States. Testing for this organism requires special procedures performed only upon request by the ordering healthcare practitioner or the New Mexico Department of Health (if an outbreak is suspected). Requests for Cyclospora testing should be written on the requisition.

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