Reference Range: |
IgG Interpretation:
1.50 or greater
|
IgG positive. An index value of >1.50 indicates IgG
antibodies to West Nile virus were detected. The presence of IgG antibodies
is presumptive evidence that the patient was or is infected with (or exposed
to) West Nile virus. A patient can be IgG positive because of
cross-reactivity to CMV and/or bunyaviruses. Other members of the
Flaviviridae family, such as St. Louis encephalitis show extensive
cross-reactivity with West Nile virus, therefore serologic testing specific for
these species should also be performed. Results should be used in correlation
to clinical history or other data.
|
1.30-1.49
|
IgG equivocal. Index values in this range are considered an
equivocal result. It is recommended that samples with equivocal results be
redrawn two or more weeks later and retested with this assay.
|
1.29 or less
|
IgG negative. An index value of <1.30 indicates IgG
antibodies to West Nile virus were not detected. The absence of IgG
antibodies is presumptive evidence that the patient was not infected with West Nile or another flavivirus. However the sample may have been drawn before antibodies
were detectable, or the patient may be immunosuppressed. If infection is
suspected, another sample should be drawn 7-14 days later and retested.
|
IgM Interpretation
Greater than 1.10
|
IgM positive. An index value of >1.10 indicates IgM
antibodies to West Nile virus were detected. The presence of IgM antibodies
is presumptive evidence that the patient was or is infected with (or exposed
to) West Nile virus. A patient can be IgM positive but not currently infected
with West Nile virus because of 1) cross-reactivity to other flaviviruses,
rheumatoid factor or enteroviruses, or 2) IgM antibodies from previous
infections may be present for over 500 days. Because other members of the
Flaviviridae family, such as St. Louis encephalitis show extensive
cross-reactivity with West Nile virus, serologic testing specific for these
species should also be performed. Results should be used in correlation to
clinical history or other data.
|
0.90-1.10
|
IgM equivocal. Index values in this range are considered an
equivocal result. It is recommended that samples with equivocal results be
redrawn two or more weeks later and retested with this assay.
|
0.89 or less
|
IgM negative. An index value of <0.90 indicates IgM
antibodies to West Nile virus were not detected. The absence of IgM
antibodies is presumptive evidence that the patient was not infected with West Nile or another flavivirus. However the sample may have been drawn before antibodies
were detectable, or the patient may be immunosuppressed. If infection is
suspected, another sample should be drawn 7-14 days later and retested.
|
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