West Nile virus (WNV) is an arthropod borne virus of public health importance. WNV are small spherical, enveloped particles containing single-stranded positive-sense RNA genome.The viral genome is approximately 11,000 nucleotides in length. WNV is a member of the genus flavivirus and belongs to the Japanese encephalitis virus (JEV) antigenic complex under family flaviviridae. The other members of the serocomplex are Japanese encephalitis, Murray Valley encephalitis, Alfuy, Kokobera. WNV is reported to be maintained in the nature in a cycle involving certain birds and mosquitoes. Mosquitoes are principle vectors of WNV. Outbreaks of WNV infection coincided with the increased population of the Culex mosquitoes during summer in temperate regions and during rainy seasons in tropics. In India, presence of West Nile antibodies in humans was first reported from Bombay (now Mumbai) by Banker in 1952. Smithburn et al confirmed the report by detecting the WNV neutralizing antibodies. During a post sero-epidemiological study, Risbud et al, detected WNV neutralizing antibodies among humans at South Arcot district of Tamil Nadu. WNV has been isolated from sporadic cases of encephalitis and mosquitoes.
Koutango West Nile encephalitis is an infection of the brain that is caused by a virus known as the West Nile virus. This virus was first identified in Uganda in 1937. It is commonly found in Africa, West Asia, and the Middle East. West Nile virus also is called West Nile fever or West Nile encephalitis. West Nile virus (WNV) is an infection that is transmitted to humans primarily by mosquitoes that have bitten infected birds. The virus is not passed directly from person-to-person, but there have been rare cases of WNV being transmitted to others through blood donations, organ transplants, and from a mother to child through breast milk.
About 80% of people infected with WNV experience no symptoms. In the other 20%, it causes flu-like symptoms such as headache, fever, nausea, muscular weakness, and/or a skin rash on the back or chest. These symptoms usually resolve without treatment within a few days to a few weeks. Only about 1 in 150 people infected with WNV becomes seriously ill with an infection that affects the central nervous system. These people may experience severe symptoms such as confusion, convulsions, high fever, neck stiffness, headaches, or a coma. They may have encephalitis and/or meningitis and/or may experience muscular paralysis. This serious form of WNV is much more common in the elderly and in the immunocompromised. While most symptoms resolve within several weeks, some nerve damage and paralysis may linger or be permanent. A nucleic acid amplification test (NAAT) amplifies and measures the West Nile virus's genetic material to detect the presence of the virus. This test can detect a current infection with the virus often before antibodies to the virus are detectable. While it can specifically identify the presence of WNV, there must be a certain amount (number of copies) of virus present in the sample in order to detect it.
Taqman Real time PCR assay.
• Detect acute infection prior to seroconversion (ie, within 1-2 weeks post-exposure).
• Assess viral measured by changes in the WNV levels.
• Assess prognosis and early diagnosis for better patient cure.
• Confirm active WNV virus infection In patient.
Every day.
3-4 days.
Cerebrospinal fluid .Blood, serum, plasma, Collect in: Lavender (EDTA), pink (K2EDTA), or serum separator tube. Stability collection to initiation of testing On Cells: Ambient: 4 hours; after separation from cells: Refrigerated: 48 hours; Frozen at -20°C: 72 hours; Frozen at -70°C: 4 months. Do not thaw avoid repeated freezing and thawing.
NOTE: Cerebrospinal fluid collected from a spinal tap and/or a blood sample drawn from a vein in your arm.
Separate serum or plasma from cells within 24 hours.
Refrigerate specimen's at 2°C-4°C.
Heparinized specimens, Hemolysis sample, Quantity not sufficient for analysis, specimen grossly contaminated, specimen too old, frozen whole blood specimen, specimen leaky or tube broken.
This test can quantitate/detect West Nile virus (WNV) RNA over the linear range 80-108 copies/mL. However this does not mean that lower copies or higher copies cannot be detected. The lower copies can be detected in some cases. This is a limitation of the currently available extraction systems. A negative result does not preclude the presence of West Nile virus (WNV) infection because results depend on adequate/proper patient sample storage and transportation as RNA is fragile and thermo labile, absence of inhibitors and sufficient RNA to be detected. A negative test cannot be used to definitely rule out the presence of WNV. A RT-PCR may detect WNV as long as the virus is actively replicating in the person.
The result of this test must always be correlated with clinical status and history of the patient and other relevant data and should not be used alone for the interpretation.