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Ova & Parasite (O&P) Exams

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Organism Index (A-Z)

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 |


 

 

DIAGNOSTIC MEDICAL PARASITOLOGY COMPUTER COMMENTS

 

SUBMISSION OF STOOL SPECIMENS

 

RESULT or SITUATION

REPORT COMMENT(S)

INTERPRETATION DISCUSSION

Submission of a single stool specimen for Ova and Parasite examination

One stool specimen is not sufficient for the recovery of intestinal parasites (only a 50% recovery); 2 specimens are recommended, while 3 offers the best chance of organism recovery

 

While 3 specimens collected over a 10 day period is the best approach, receipt of 2 specimens is acceptable

Submission of 2 stool specimens for Ova and Parasite examination

Although submission of 2 stool specimens is acceptable, 3 specimens collected over a 10 day period provide the best approach for organism recovery.

While 2 specimens is now considered acceptable, 3 specimens will allow the most complete percentage recovery of intestinal parasites present.

 

 

 

 

EXAMINATION OF FECAL SPECIMENS:

 

RESULT

REPORT COMMENT(S)

INTERPRETATION DISCUSSION

No Parasites Seen

Antibiotics such as metronidazole or tetracycline may interfere with the recovery of intestinal parasites, particularly the protozoa.

 

If a patient is symptomatic and intestinal parasites are suspected, this comment may be helpful for the physician, particularly if the patient has received any of these antibiotics.

 

Entamoeba histolytica

            Trophozoites containing ingested           RBCs

Pathogenic; cause of amebiasis

Result based on presence of ingested RBCs within the trophozoite cytoplasm and/or a positive result using the fecal immunoassay specific for the pathogen, Entamoeba histolytica

 

Entamoeba histolytica/E. dispar group

            Trophozoites (containing no             ingested RBCs) and/or cysts

 

Differentiation between the pathogen Entamoeba histolytica and the non-pathogen Entamoeba dispar not possible based on organism morphology; if ingested RBCs NOT seen, unable to differentiate the two organisms OR

Unable to determine pathogenicity from organism morphology OR

Depending on patient’s clinical condition, treatment may be appropriate.

 

A fecal immunoassay specific for the pathogen, Entamoeba histolytica, can be performed on fresh stool to separate out E. histolytica and E. dispar

NOTE:  Could be added as another comment if you offer the test (see below)

 

Differentiation of E. histolytica from E. dispar

To determine the presence or absence of pathogenic Entamoeba histolytica, submit a fresh stool specimen.

 

The fecal immunoassay specific for the pathogen, Entamoeba histolytica, requires fresh stool for testing.

Blastocystis hominis

The name Blastocystis hominis contains approximately 10 different organisms, none of which can be differentiated on the basis of organism morphology; some are pathogenic and some are non-pathogenic.  If no other pathogens are found, B. hominis may be the cause of patient symptoms AND

Other organisms capable of causing diarrhea should also be ruled out.

 

Until there are testing options to differentiate between the pathogens and non-pathogens, it is important that the physicians know that some strains of B. hominis are pathogenic.  Quantitate these organisms (rare, few, moderate, many, packed).

 

Giardia lamblia

            Other names which refer to the       same organism, Giardia lamblia,           include:

                        Giardia intestinalis

                        Giardia duodenalis

Pathogenic

If fecal immunoassays are performed, the testing of two separate stools (collected at least one day apart) is recommended before the patient is considered negative.  The testing of two stools is not required for Cryptosporidium spp.

 

Entamoeba hartmanni

Entamoeba coli

Endolimax nana

Iodamoeba bütschlii

Chilomastix mesnili

Pentatrichomonas hominis

Enteromonas hominis

Retortamonas intestinalis

            Trophozoites and/or cysts

 

Nonpathogenic; treatment not recommended; however, recovery of these organisms indicates the patient has ingested something contaminated with fecal material (same infectivity route for pathogens)

 

It is important to report nonpathogens; patient may be infected with one or more pathogen(s) – not yet found.

Microsporidia (fecal and urine specimens)

   Enterocytozoon bieneusi

   Encephalitozoon intestinalis

The report would indicate “Microsporidian spores present”

“Probably Enterocytozoon bieneusi or Encephalitozoon intestinalis or both; these tend to disseminate from the GI tract to the kidneys. Identification to the genus/species level not possible from stained smears.”

These are the two most likely organisms present; these comments are very helpful, especially in indicating that the two organisms cannot be identified to the genus or species levels on the basis of Calcofluor white or modified trichrome stained smears.

 

 

EXAMINATION OF BLOOD SPECIMENS*:

 

RESULT

REPORT COMMENT(S)

INTERPRETATION DISCUSSION

No Parasites Seen

           

The submission of a single blood specimen will not rule out malaria; submit additional bloods every 4-6 hours for 3 days if malaria remains a consideration.

 

It is important to make sure the physician knows that examination of a single blood specimen will not rule out malaria.

 

Plasmodium spp. Seen

Unable to rule out Plasmodium falciparum or Plasmodium knowlesi

Since P. falciparum and P. knowlesi cause the most severe symptoms, it is important to let the physician know these species have NOT been ruled out.

 

Plasmodium spp., possible mixed infection

Unable to rule out Plasmodium falciparum or Plasmodium knowlesi

Since P. falciparum and P. knowlesi cause the most severe symptoms, it is important to let the physician know these species have NOT been ruled out.

 

Negative for parasites using automated hematology instruments

Automated Hematology instruments will not detect low malaria parasitemias seen in immunologically naïve patients (travelers)

In patients who have never been exposed to malaria (immunologically naïve), they will become symptomatic with very low parasitemias that will not be detected using automation (0.001 to 0.0001%)

 

*NOTE:  Use of the BinaxNOW (Inverness Medical) malaria rapid test may help detection of mixed infections (STAT test).  This test is FDA approved and the external malaria control is now also available (BinaxNOW® Malaria Product Fact Sheet

Test Kit & Positive Control.).  However, if test is negative, thick and thin blood film examination is mandatory (STAT).