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Test Code WNV West Nile Virus

Methodology

Enzyme Immunoassay (EIA)

Serological specimens submitted for arbovirus testing will be evaluated using an IgM antibody capture enzyme-linked immunosorbent assay (MAC-ELISA) and an IgG ELISA to identify St. Louis encephalitis (SLE), Eastern Equine encephalitis (EEE), LaCrosse encephalitis (LAC), and West Nile Virus (WNV)-reactive antibody. If SLE, EEE, LAC, or WNV-reactive antibodies are present, specimen will be forwarded to the Centers for Disease Control and Prevention (CDC) for plaque reduction neutralization testing (PRNT) confirmation. Real-time RT-PCR will be performed on biopsy and postmortem tissue specimens, and acute serum and spinal fluid. Viral isolation is available upon request.

Performing Laboratory

Commonwealth of Virginia Division of Consolidated Laboratory Services (DCLS)

Specimen Requirements

Any adult or pediatric patient admitted to a hospital with a presumed diagnosis of viral encephalitis, or with focal central nervous system findings and fever should submit a whole blood or serum specimen for diagnostic testing at DCLS following guidelines listed below. Recommended criteria for suspect cases on WNV-any patient with viral encephalitis (criteria a, b, and c below) with or without associated muscle weakness (criteria d).

A. Fever ≥38o C or 100o F, and

B. Altered mental status (altered level of consciousness, agitation, lethargy) and/or other evidence of cortical involvement  (eg focal neurologic findings, seizures), and

C. Spinal fluid pleocytosis with predominant lymphocytes and/or elevated protein and a negative gram stain and culture, and/or

D. Muscle weakness (especially flaccid paralysis) confirmed by neurologic exam or by electromyogram (EMG).

 

Submit only 1 of the following specimens:

 

Serum

1. Collect 2 mL of serum in a sera plastic tube (preferred) or 5 mL of coagulated whole blood.

2. Wrap specimen in absorbent material, pack in a sealable plastic bag.

3. Place bag in a rigid container (styrofoam box or cardboard mailing container).

4. Place container and a cold pack in a styrofoam cooler for shipment.

5. Send specimen refrigerated.

Note:  1. Include a encephalitis/initial case report form for each patient to be tested. Fill out form as completely as possible. Accurate interpretation of serologic findings requires knowledge of specimen. It is imperative that the following data accompany specimens submitted:

A. Symptom onset date

B. Date of specimen collection

C. Unusual immunological status of patient

D. Current address and travel history

E. History of prior vaccination against flavivirus disease

F. Brief clinical summary including suspected diagnosis

2. Coolers should be shipped 24-hours/overnight delivery.

3. If you are hand carrying specimen, please observe packing instructions above to secure specimen in transit.

 

Spinal Fluid

1. Collect 1 mL of spinal fluid. Place specimen in a screw-capped, sterile container.

2. Wrap specimen in absorbent material, packed in a sealable plastic bag, and then placed into a second sealable bag.

3. Send specimen frozen on enough dry ice to ensure it will remain frozen.

4. Maintain sterility and forward promptly.

Note:  1. Include a encephalitis/initial case report form for each patient to be tested. Fill out form as completely as possible. Accurate interpretation of serologic findings requires knowledge of specimen. It is imperative that the following data accompany specimens submitted:

A. Symptom onset date

B. Date of specimen collection

C. Unusual immunological status of patient

D. Current address and travel history

E. History of prior vaccination against flavivirus disease

F. Brief clinical summary including suspected diagnosis

2. Coolers should be shipped 24-hours/overnight delivery.

 

Tissue

1. Collect 1.0 g of brain, biopsy, or postmortem tissue.

2. Wrap specimen in absorbent material, packed in a sealable plastic bag, and then placed into a second sealable bag.

3. Place specimen in a cooler with dry ice for shipment.

4. Send specimen frozen on enough dry ice to ensure it will remain frozen.

Note:  1. Include a encephalitis/initial case report form for each patient to be tested. Fill out form as completely as possible. Accurate interpretation of serologic findings requires knowledge of specimen. It is imperative that the following data accompany specimens submitted:

A. Symptom onset date

B. Date of specimen collection

C. Unusual immunological status of patient

D. Current address and travel history

E. History of prior vaccination against flavivirus disease

F. Brief clinical summary including suspected diagnosis

2. Coolers should be shipped 24-hours/overnight delivery.

Reference Values

An interpretive report will be provided.

Day(s) Test Set Up

Monday through Friday