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Unit Code 83918:
Western Equine Encephalitis Antibody Panel, IgG and IgM, Spinal Fluid

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Useful For

Aiding the diagnosis of WEE

Clinical Information

The virus that causes western equine encephalitis (WEE) is widely

distributed throughout the United States and Canada; disease

occurs almost exclusively in the western states and Canadian

provinces. The relative absence of the disease in the eastern

United States probably reflects a paucity of the vector mosquito

species, Culex tarsalis, and possibly a lower pathogenicity of local

virus strains.

 

The disease usually begins suddenly with malaise, fever, and

headache, often with nausea and vomiting. Vertigo, photophobia,

sore throat, respiratory symptoms, abdominal pain, and myalgia

are also common. Over a few days, the headache intensifies;

drowsiness and restlessness may merge into a coma in severe

cases. In infants and children, the onset may be more abrupt than

for adults. WEE should be suspected in any case of febrile Central

Nervous System (CNS) disease from an endemic area. Infants are

highly susceptible to CNS disease and about 20% of cases are

under 1 year of age. There is an excess of males with WEE clinical

encephalitis, averaging about twice the number of infections

detected in females. After recovery from the acute disease, patients

may require from several months to 2 years to overcome the fatigue,

headache, and irritability. Infants and children are at a higher risk of

permanent brain damage after recovery than adults.

 

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, sex, and 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.

Reference Values

IgG:  <1:10

IgM:  <1:10

 

Reference values apply to all ages.

Interpretation

A positive result indicates intrathecal synthesis of antibody and is

indicative of neurological infection.

Cautions

All results must be correlated with clinical history and other data

available to the attending physician.

 

False-positive results may be caused by breakdown of the blood-

brain barrier, or by the introduction of blood into the CSF at collection.

 

WEE and eastern equine encephalitis viruses show some cross-

reactivity; however, antibody response to the infecting virus is typically

at least 8-fold higher.

Clinical Reference

1.   Gonzalez-Scarano F, Nathanson N:  Bunyaviruses. In Fields

      Virology. Volume 1. 2nd Edition. Edited by BN Fields, DM Knipe.

      New York, Raven Press, 1990, pp 1195-1228

 

2.   Donat JF, Rhodes KH, Groover RV, Smith TF:  Etiology and

      outcome in 42 children with acute nonbacterial meningoencephalitits.

      Mayo Clin Proc 1980;55:156-160

 

3.   Tsai TF:  Arboviruses  In Manual of Clinical Microbiology. 7th

      edition. Edited by PR Murray, EJ Baron, MA Pfaller, et al.

      Washington, DC, American Society for Microbiology, 1999,

      pp 1107-1124

 

4.   Calisher CH:  Medically important arboviruses of the United

      States and Canada. Clin Microbiol Rev 1994;7:89-116

Key