West Nile IgG antibodies are often not detectable until day 4 or 5 of illness.
In a person who is IgM positive but IgG negative, a convalescent phase specimen obtained 7-14 days after the initial specimen should be tested to document IgG seroconversion.
West Nile virus (WNV) IgM is usually detectable in serum specimens from WNV-infected people at the time of clinical presentation. Because serum IgM antibody may persist for more than a year in some patients, its presence may indicate WNV infection in the previous year and be unrelated to the current clinical presentation.
Antibodies induced by other flavivirus infections (e.g. Dengue virus, St. Louis encephalitis virus) may show cross-reactivity with WNV.
West Nile virus (WNV) is a mosquito-borne flavivirus (single-stranded RNA) that primarily infects birds but can also infect humans and horses.
WNV was first isolated in 1937 from an infected person in the West Nile district of Uganda. Until the viral infection was recognized in 1999 in birds in New York City, WNV was found only in the Eastern Hemisphere, with wide distribution in Africa, Asia, the Middle East, and Europe.
Most recently, in 2012, a total of 5,674 cases of WNV were reported to the Centers for Disease Control and Prevention (CDC), among which 2,873 (51%) were classified as neuroinvasive disease (eg, meningitis or encephalitis) and 286 (5%) cases resulted in death.
Clinical progression of disease and symptoms:
Most people who are infected with WNV will not develop clinical signs of illness. It is estimated that about 20% of those who become infected will develop West Nile fever with mild symptoms, including fever, headache, myalgia, and occasionally a skin rash on the trunk of the body. Case fatality rates among patients hospitalized during recent outbreaks have ranged from 4% to 14%.
Advanced age is the most important risk factor for death, and patients older than 70 years of age are at particularly high risk.
The presence of IgG-class antibodies to West Nile virus (WNV) in serum indicates infection with WNV at some time in the past. By 3 weeks postinfection, virtually all infected persons should have developed IgG antibodies to WNV. If acute-phase infection is suspected, serum specimens drawn within approximately 7 days postinfection should be compared with a specimen drawn approximately 14 to 21 days postinfection to demonstrate rising IgG antibody levels between the 2 serum specimens.
Our specialized data entry service is designed to seamlessly integrate your laboratory results into your private dashboard. Just send in your lab test results—whether it's an image or a file—and our skilled data entry team will handle the rest. We accommodate various file formats like PDFs, JPGs, and Excel.
The first report is complimentary. After that, the data entry service is priced at $15 per report, unless it's part of your subscribed plan. It's an ideal solution whether you have numerous reports to upload or if your schedule doesn't permit self-data entry.
We strive to make the data entry process easy for you. Whether by offering dozens of templates to choose from that pre-populate the most popular laboratory panels or by giving you instant feedback on the entered values. Our data entry forms are an easy, fast, and convenient way to enter the reports yourself. There is no limit on how many lab reports you can upload.
track personal results
track multiple client's results
own it for life
for health professionals
for personal lab results
own it for life
Level up your lab report analysis with our Pro plan, built for health practitioners like you.
Health Business Account
Unlock additional Pro plans when you sign up.