Laboratory Lab results are too important to go anywhere else.

West Nile Antibody, IgG and IgM

Viral Encephalitis, Arbovirus Ab, Mosquito- and bird-borne Virus Ab

Test Codes

EPIC: LAB7617, Beaker: XARIM, Mayo: WNS

Department

Send Outs

Specimen Collection Criteria

Collect (preferred specimen): One Gold-top SST tube.
Also acceptable: One plain Red-top tube.

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells within two hours of collection. Transfer serum to a plastic transport tube and refrigerate (2-8°C or 36-46°F).

Preparation for Courier Transport

Transport: 0.5 mL serum, refrigerated (2-8°C or 36-46°F). (Minimum: 0.4 mL)

Rejection Criteria

• Hemolyzed specimens.
• Severely lipemic specimens.
• Icteric specimens.
• Specimens not collected and processed as indicated.

In-Lab Processing

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells within two hours of collection. Transfer serum to a plastic transport tube and refrigerate (2-8°C or 36-46°F).

Transport: 0.5 mL serum, refrigerated (2-8°C or 36-46°F). (Minimum: 0.4 mL)

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): unacceptable
Refrigerated (2-8°C or 36-46°F): 14 days
Frozen (-20°C/-4°F or below): 14 days

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.

Laboratory

Sent to Mayo Clinic Laboratories in Rochester, MN.

Performed

Monday, Wednesday, Friday.
Results available in 2-5 days.

Reference Range

By report.

Test Methodology

Semi-Quantitative Enzyme-Linked Immunosorbent Assay.

Clinical Disease

Most people infected with West Nile virus have no symptoms of illness, but some may become ill 3 to 15 days after the bite of an infected mosquito. Studies have shown that about 1 in 4 infected persons will have mild illness with fever, headache and body aches, sometimes with skin rash and swollen lymph glands. More severe infection (encephalitis) is less common and may be marked by headache, high fever, stiff neck, stupor, disorientation, coma, tremors, convulsions, muscle weakness, and paralysis. In a few cases, mostly among the elderly, death may occur. Persons with severe or unusual headaches should seek medical care as soon as possible.

Epidemiology

The risk of getting West Nile encephalitis is limited to persons in areas where virus activity occurs and is higher in persons 50 years of age and older.

Transmission

People get West Nile encephalitis from the bite of a mosquito that is infected with West Nile virus. West Nile virus in NOT transmitted from person to person.

Reference

1. Craven, R. Togaviruses In Belshe, R. Textbook of Human Virology, Second Edition, 1991;665 (Eastern Equine Encephalitis)
2. Craven, R. Flaviviruses In Belshe, R. Textbook of Human Virology, Second Edition, 1991;636. (St. Louis Encephalitis)
3. Michigan Department of Agriculture, General Information on West Nile Virus, http://www.mda.state.mi.us/consumer/westnilevirus/geninfo.html (West Nile Virus)

CPT Codes

86789 and 86788.
LOINC:  IgG 29566-7, 29780-4, IgM 29567-5

Contacts

Last Updated

9/14/2023