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Ova & Parasite (O&P) Exams

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Informational Tables

- Parasite Classification | - Parasite, Body Site |
- Stool Testing Order Recommendations | - STAT Testing |
- Fecal Fixatives | - Stool Collection Options | - Report Comments |
- Tips for Fecal ImmunoAssay | - Malaria (5 Species) |
- Malaria (5 Species) Images | - Rapid Malaria Testing |
- Malaria Parasitemia Method | - Malaria Parasitemia Interpretation |


stool testing order recommendations (for physicians)

 

Patient and/or Situation

Test Ordereda

 

Follow-up Test Ordered

 

wPatient with diarrhea and AIDS or other cause of immune deficiency

wPotential waterborne outbreak (municipal/city water supply)

 

Cryptosporidium or Giardia/Cryptosporidium immunoassay

 

 

If immunoassays are negative and symptoms continue, special tests for microsporidia (modified trichrome stain) and other coccidia (modified acid-fast stain) and O&P exam should be performed

 

 

wPatient with diarrhea (nursery school, day care center, camper, backpacker)

wPatient with diarrhea and potential waterborne outbreak (resort setting)

wPatient with diarrhea from areas where Giardia is the most common parasite found

 

 

Giardia or Giardia/Cryptosporidium immunoassay (perform testing on two stools before reporting as negative)

 

Particularly relevant for areas of the U.S. where Giardia most common organism found

 

If immunoassays are negative and symptoms continue, special tests for microsporidia and other coccidia (see above) and O&P exam should be performed

 

 

wPatient with diarrhea and relevant travel history

wPatient with diarrhea who is a past or present resident of a developing country

wPatient in an area of the United States where parasites other than Giardia are found

 

 

O&P exam, Entamoeba histolytica/E. dispar immunoassay; immunoassay for confirmation of E. histolytica; various tests for Strongyloides may be relevant (even in the absence of eosinophilia)

 

If exams are negative and symptoms continue, special tests for coccidia and microsporidia should be performed

 

wPatient with unexplained eosinophilia and possible diarrhea; if chronic, patient may also have history of respiratory problems (larval migration) and/or sepsis or meningitis (hyperinfection)

 

 

Although the O&P exam is a possibility, the agar plate culture for Strongyloides stercoralis (more sensitive than the O&P exam) is recommended

 

If tests are negative and symptoms continue, additional O&P exams and special tests for microsporidia and other coccidia should be performed

 

 

wPatient with diarrhea (suspected food-borne outbreak)

 

Test for Cyclospora cayetanensis (modified acid-fast stain, autofluorescence)

 

If tests are negative and symptoms continue, special procedures for microsporidia and other coccidia and O&P exam should be performed

 

 

aDepending on the particular immunoassay kit used, various single or multiple organisms may be included. Selection of a particular kit depends on many variables: clinical relevance, cost, ease of performance, training, personnel availability, number of test orders, training of physician clients, sensitivity, specificity, equipment, time to result, etc.  Very few laboratories will handle this type of testing exactly the same.  Many options are clinically relevant and acceptable for good patient care.  It is critical that the laboratory report indicate specifically which organisms could be identified using the kit; a negative report should list the organisms relevant to that particular kit.