West Nile Virus Test

This is a test to determine the cause of viral meningitis (inflammation of the lining of the brain and spinal cord) or encephalitis (inflammation of the brain) that occurs during the summer season; to detect the presence of West Nile virus (WNV) and to track its spread.

West Nile virus (WNV) is an infection that is transmitted to humans primarily by mosquitoes. It is not usually transmitted person-to-person, but there have been cases of WNV being passed on to others through blood donations, organ transplants, and rarely from a mother to child through breast milk. About 80% of people infected with WNV experience no symptoms. In the other 20%, it causes relatively mild flu-like symptoms such as headache, fever, and muscular weakness that resolve without treatment after a few days to a few weeks. Only 1 in 150 people infected with WNV becomes seriously ill with an infection that affects the central nervous system. These patients may have encephalitis (inflammation of the brain) and/or meningitis (inflammation of the lining of the brain and spinal cord) and/or may experience muscular paralysis. This serious form of WNV is much more common in the elderly and in the immunocompromised. While the inflammation eventually resolves, some nerve damage and paralysis may linger and/or be permanent.


Cerebrospinal fluid is collected from a spinal tap and/or a blood sample is drawn from a vein in your arm.



Ranges for normal findings may vary among different laboratories and hospitals. You should always check with your doctor after having lab work or other tests done to discuss the meaning of your test results and whether your values are considered within normal limits.


Your caregiver will go over the test results with you and discuss the importance and meaning of your results, as well as treatment options and the need for additional tests if necessary.


It is your responsibility to obtain your test results. Ask the lab or department performing the test when and how you will get your results.