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Test Code EHOLG Entamoeba histolytica Antibody, Serum


Ordering Guidance


Direct detection of Entamoeba histolytica in fecal specimens is recommended to diagnose intestinal amebiasis. See OPE / Ova and Parasite, Travel History or Immunocompromised, Feces or OAPNS / Ova and Parasite, Microscopy, Varies.



Specimen Required


Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions: Centrifuge and aliquot serum into plastic vial.


Secondary ID

616732

Useful For

As an adjunct in the diagnosis of extraintestinal, invasive amebiasis

Method Name

Enzyme-Linked Immunosorbent Assay (ELISA)

Reporting Name

E. histolytica Ab, IgG, S

Specimen Type

Serum

Specimen Minimum Volume

0.4 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 14 days
  Frozen  30 days

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Heat-inactivated specimen Reject

Clinical Information

Amebiasis is an infection caused by the protozoan parasite, Entamoeba histolytica. The infection is acquired by ingestion of cysts in fecally contaminated food or water; excystation and infection occur in the large intestine. After excystation, trophozoites attach to the intestinal wall and excrete extracellular enzymes that enable invasion of the mucosa and spread to other organs, especially the liver and lung where abscesses may develop.

 

Amebiasis (or amebic dysentery) can cause bloody diarrhea accompanied by fever and prostration. White and red blood cells are found in the stool. Liver abscess can develop several weeks to months later producing hepatomegaly and fever.

 

Serology may be particularly useful in supporting the diagnosis of invasive disease with E histolytica, which is most commonly associated with amebic liver abscess. Serology should not be used to identify or diagnose amebic dysentery due to poor sensitivity in acute, noninvasive disease.

Reference Values

Negative

Reference values apply to all ages.

Interpretation

Negative: No antibodies to Entamoeba histolytica detected. This assay is intended for assessment of invasive amebiasis. Repeat testing in 2 to 3 weeks if clinically indicated.

 

Equivocal: Recommend follow-up testing in 10 to 14 days if clinically indicated.

 

Positive: Results are suggestive of current or past infection with Entamoeba histolytica. Direct detection of E histolytica in stool or other specimen sources is recommended to diagnose acute amebiasis.

Cautions

Previous episodes of intestinal amebiasis may produce a positive serology.

 

Serologic results should be used as an aid in diagnosis and should not be interpreted as diagnostic by themselves.

Clinical Reference

1. Bruckner DA. Amebiasis. Clin Microbiol Rev. 1992;5(4):356-369. doi: 10.1128/CMR.5.4.356

2. Petri WA, Haque R, Moonah SN: Entamoeba species, including amebic colitis and liver abscess. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Elsevier; 2020:3273-3286

Method Description

Microplates are coated with specific antigens to bind corresponding antibodies of the sample. After washing the wells to remove all unbound sample material, a horseradish peroxidase-labelled conjugate is added. This conjugate binds to the captured antibodies. In a second washing step, unbound conjugate is removed. The immune complex formed by the bound conjugate is visualized by adding tetramethylbenzidine substrate, which gives a blue reaction product. The intensity of this product is proportional to the amount of specific antibodies in the sample. Sulfuric acid is added to stop the reaction. This produces a yellow endpoint color. Absorbance at 450/620 nm is read using an enzyme-linked immunosorbent assay microwell plate reader.(Package insert: Entamoeba histolytica ELISA IgG Test kit. Gold Standard Diagnostics; GSD-ENTG-120705.F; 01/12/2021)

Day(s) Performed

Tuesday, Thursday

Report Available

Same day/1 to 5 days

Specimen Retention Time

14 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

86753

LOINC Code Information

Test ID Test Order Name Order LOINC Value
EHOLG E. histolytica Ab, IgG, S 22285-1

 

Result ID Test Result Name Result LOINC Value
EHOLG E. histolytica Ab, IgG, S 22285-1

Forms

If not ordering electronically, complete, print, and send an Infectious Disease Serology Test Request (T916) with the specimen.