A West Nile virus IgG is a test to know about the physical health of the person through the presence of its symptoms transmitted through infected birds directly or by its presence in the antibody. Generally, the viral infection is caused by mosquitoes. The symptoms are hardly visible in most of the cases, but for the rest few, the symptoms include developing a fever, headache, vomiting or rash. The lab report generated by this test shows virtually the presence of IgG class antibodies in a serum specimen. In most cases, it will be detectable for 1 or 2 months following the disease revolution for the others it may take 12 months or longer.