Ordering Recommendation

Not recommended as a stand-alone test. Refer to Arbovirus Antibodies, IgG and IgM, Serum (2001594).




Semi-Quantitative Indirect Fluorescent Antibody/Semi-Quantitative Enzyme-Linked Immunosorbent Assay


Tue, Fri


1-5 days

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation

Serum separator tube. Also acceptable: Plain red.

Specimen Preparation

Separate serum from cells ASAP or within 2 hours of collection. Transfer 1 mL serum to an ARUP Standard Transport Tube. (Min: 0.4 mL) Parallel testing is preferred and convalescent specimens must be received within 30 days from receipt of acute specimens. Mark specimens plainly as "acute" or "convalescent."

Storage/Transport Temperature


Unacceptable Conditions

Plasma. Contaminated, heat-inactivated, hemolyzed, or severely lipemic specimens.


After separation from cells: Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles)

Reference Interval

Test Number
Reference Interval
  West Nile Virus Ab, IgM, Ser 0.89 IV or less
  California Encephalitis IgM Less than 1:16
  St. Louis Encephalitis Ab, IgM, Serum Less than 1:16
  Eastern Equine Enceph Ab, IgM Less than 1:16
  Western Equine Enceph Ab, IgM, Ser Less than 1:16

Interpretive Data

Component Interpretation
West Nile Virus Antibody, IgM by ELISA, Serum 0.89 IV or less: Negative - No significant level of West Nile virus IgM antibody detected.
0.90-1.10 IV: Equivocal - Questionable presence of West Nile virus IgM antibody detected.  Repeat testing in 10-14 days may be helpful.
1.11 IV or greater: Positive - Presence of IgM antibody to West Nile virus detected, suggestive of current or recent infection.

Compliance Category



Hotline History


CPT Codes

86651; 86652; 86653; 86654; 86788


Component Test Code* Component Chart Name LOINC
0050236 West Nile Virus Ab, IgM, Ser 38166-5
0098731 California Encephalitis IgM 10905-8
0098732 St. Louis Encephalitis Ab, IgM, Serum 10907-4
0098733 Eastern Equine Enceph Ab, IgM 10898-5
0098734 Western Equine Enceph Ab, IgM, Ser 6958-3
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.


Arbovirus Antibodies, IgM, Serum