West Nile Virus, IgM
Label Mnemonic: ARBWNV
Epic Lab Code: LAB7533
Downtime Form: A-1a Miscellaneous Request
Commercial Mail-out Laboratory
5231 RCP
Specimen Instructions:
Acute and convalescent specimens must be labeled as such; parallel testing is preferred and convalescent specimens must be received within 30 days from receipt of the acute specimens. Please mark specimen plainly as "acute" or "convalescent."
Collection Medium:
Red top tube 5 mL (Clot Activator)
Preferred Minimum: 1 mL serum in a red top tube
Absolute Minimum: 0.15 mL serum in a red top tube
Rejection Criteria:
Plasma. Contaminated, hemolyzed, heat-inactivated, or severely lipemic specimens.
Turn Around Time:
1-8 days upon receipt at reference laboratory
Reference Range:
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.
Interpretive Data:
This test is intended to be used as a semi-quantitative means of detecting West Nile virus-specific IgM in serum specimens in which there is a clinical suspicion of West Nile virus infection. This test should not be used solely for quantitative purposes, nor should the results be used without correlation to clinical history or other data. Because other members of the Flaviviridae family, such as St. Louis encephalitis virus, show extensive cross-reactivity with West Nile virus, serologic testing specific for these species should be considered.

Seroconversion between acute and convalescent sera is considered strong evidence of current or recent infection. The best evidence for infection is a significant change on two appropriately timed specimens, where both tests are done in the same laboratory at the same time.
Semi-Quantitative Enzyme-Linked Immunosorbent Assay
CPT Code: