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Test ID STRNG Strongyloides Antibody, IgG, Serum

Useful For

Screening for the presence of IgG-class antibodies to Strongyloides

 

Not useful for monitoring patient response to therapy as IgG-class antibodies to Strongyloides may remain detectable following resolution of infection.

Method Name

Enzyme-Linked Immunosorbent Assay (ELISA)

Reporting Name

Strongyloides Ab, IgG, S

Specimen Type

Serum


Specimen Required


Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL


Specimen Minimum Volume

0.4 mL

Specimen Stability Information

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

Clinical Information

Strongyloidiasis is caused by Strongyloides stercoralis, a nematode endemic to tropical and subtropical regions worldwide. S stercoralis is also prominent in the southeastern United States, including in rural areas of Kentucky, Tennessee, Virginia, and North Carolina. A small series of epidemiological studies in the United States identified that between 0% to 6.1% of individuals sampled had antibodies to S stercoralis.

 

S stercoralis has a complex lifecycle that begins with maturation to the infective filariform larva in warm, moist soil. The larvae subsequently penetrate exposed skin and migrate hematogenously to the lungs, from where they ascend the bronchial tree and are swallowed. Once in the small intestine, filariform larva mature into the adult worms that burrow into the mucosa. Gravid female worms produce eggs that develop into noninfectious rhabditiform larvae in the gastrointestinal tract and are eventually released in the stool. The time from dermal penetration to appearance of Strongyloides in stool samples is approximately 3 to 4 weeks.

 

The most common manifestations of infection are mild and may include epigastric pain, mild diarrhea, nausea, and vomiting. At the site of filariform penetration, skin may be inflamed and itchy-this is referred to as "ground itch." Migration of the larva through the lungs and up the trachea can produce a dry cough, wheezing, and mild hemoptysis. Eosinophilia, though common among patients with strongyloidiasis, is not a universal finding and the absence of eosinophilia cannot be used to rule-out infection.

 

In some patients, particularly those with a depressed immune system, the rhabditiform larvae may mature into the infectious filariform larvae in the gastrointestinal tract and lead to autoinfection. The filariform larvae subsequently penetrate the gastrointestinal mucosa, migrate to the lungs and can complete their lifecycle. Low-level autoinfection can maintain the nematode in the host for years to decades. Among patients who become severely immunocompromised, however, autoinfection may lead to hyperinfection and fatal disseminated disease. Hyperinfection has also been associated with underlying human T-cell lymphotropic virus type 1 (HTLV-1) infection. Uncontrolled, the larvae can disseminate to the lungs, heart, liver, and central nervous system. Septicemia and meningitis are common in cases of Strongyloides hyperinfection due to seeding of the bloodstream and central nervous system with bacteria originating from the gastrointestinal tract.

Reference Values

Negative

Reference values apply to all ages.

Interpretation

Positive:

IgG antibodies to Strongyloides were detected, suggesting current or past infection. False-positive results may occur with other helminth infections (eg, Trichinella, Taenia solium). Clinical correlation is required.

 

Negative:

No detectable levels of IgG antibodies to Strongyloides. Repeat testing in 10 to 14 days if clinically indicated.

Clinical Reference

1. Ramanathan R, Burbelo PD, Groot S, et al: A luciferase immunoprecipitation systems assay enhances the sensitivity and specificity of diagnosis of Strongyloides stercoralis infection. J Infect Dis 2008;198(3):444-451

2. Starr MC, Montgomery SP: Soil-transmitted Helminthiasis in the United States: a systematic review-1940-2010. Am J Trop Med Hyg 2011;85(4):680-684

3. Krolewiecki AJ, Ramanathan R, Fink V, et al: Improved diagnosis of Strongyloides stercoralis using recombinant antigen-based serologies in a community-wide study in northern Argentina. Clin Vaccine Immunol 2010;17(10):1624-1630

4. Centers for Disease Control and Prevention. Global Health. Division of Parasitic Diseases and Malaria. Stongyloides. Epidemiology and Risk Factors. Accessed March 2014. Available at www.cdc.gov/parasites/strongyloides/epi.html

Day(s) and Time(s) Performed

Monday, Wednesday, Friday; 2 p.m.

Analytic Time

Same day/1 day

Test Classification

This test has been cleared, approved or is exempt by the U.S. 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

86682

LOINC Code Information

Test ID Test Order Name Order LOINC Value
STRNG Strongyloides Ab, IgG, S 34376-4

 

Result ID Test Result Name Result LOINC Value
STRNG Strongyloides Ab, IgG, S 80660-4

Testing Algorithm

See Parasitic Investigation of Stool Specimens Algorithm in Special Instructions.

Forms

If not ordering electronically, complete, print, and send a Microbiology Test Request (T244) with the specimen.