Test: West Nile Virus
West Nile Virus (WNV) is spread by mosquitoes Clinical symptoms for WNV are non-specific and infections can only be diagnosed by means of laboratory testing. Laboratory diagnosis is generally accomplished by detecting WNV-specific IgM and IgG antibodies in the serum or cerebrospinal fluid (CSF). IgM antibodies are usually detectable from 3 to 8 days after onset of illness and persist for 30 to 90 days, (longer persistence has been documented.) IgG antibodies generally are detected shortly after IgM antibodies and persist for many years following symptomatic and asymptomatic infections. The presence of IgG antibodies alone is only evidence of previous exposure.
The enzyme immunoassay (EIA) test provides a sensitive and specific, semi-quantitative assay for the detection of both IgM and IgG antibodies to WNV. Highly specific viral protein is used to detect the antibodies to WNV and limit cross-reaction with other similar viruses.