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Test Code WEEP Western Equine Encephalitis Antibody, IgG and IgM, Serum

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Method Name

Immunofluorescence Assay (IFA)

Reporting Name

West Equine Enceph Ab,IgG and IgM,S


Specimen Required


Container/Tube:

Preferred: Serum gel                 

Acceptable: Red top                                        

Specimen Volume: 0.5 mL


Specimen Type

Serum

Specimen Minimum Volume

0.15 mL

Specimen Stability Information

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

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject

Reference Values

IgG: <1:10

IgM: <1:10

Reference values apply to all ages.

Day(s) and Time(s) Performed

May through October: Monday through Friday; 9 a.m.

November through April: Monday, Wednesday, Friday; 9 a.m.

Test Classification

This test has been cleared or approved 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

86654 x 2

LOINC Code Information

Test ID Test Order Name Order LOINC Value
WEEP West Equine Enceph Ab,IgG and IgM,S 69041-2

 

Result ID Test Result Name Result LOINC Value
8193 West Equine Enceph Ab, IgG, S 6957-5
87279 West Equine Enceph Ab, IgM, S 6958-3

Useful For

Aiding the diagnosis of Western equine encephalitis

Interpretation

In patients infected with this virus, IgG antibody is generally detectable within 1 to 3 weeks of onset, peaking within 1 to 2 months, and declining slowly thereafter.

 

IgM class antibody is also reliably detected within 1 to 3 weeks of onset, peaking and rapidly declining within 3 months.

 

Single serum specimen IgG ≥1:10 indicates exposure to the virus.

 

Results from a single serum specimen can differentiate early (acute) infection from past infection with immunity if IgM is positive (suggests acute infection).

 

A 4-fold or greater rise in IgG antibody titer in acute and convalescent sera indicate recent infection.

 

In the United States it is unusual for any patient to show positive reactions to more than 1 of the arboviral antigens, although Western equine encephalitis (WEE) and Eastern equine encephalitis (EEE) antigens will show a noticeable cross-reactivity.

 

Infections with arboviruses can occur at any age. The age distribution depends on the degree of exposure to the particular transmitting arthropod relating to age and sex, as well as the occupational, vocational, and recreational habits of the individuals. Once humans have been infected, the severity of the host response may be influenced by age: WEE tends to produce the most severe clinical infections in young persons. Infection in males is primarily due to working conditions and sports activity taking place where the vector is present.

Forms

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

Testing Algorithm

See Mosquito-borne Disease Laboratory Testing in Special Instructions.