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West Nile virus (WNV) infection can cause severe fever,
encephalitis, meningitis, and death. This mosquito-borne virus is common in
parts of Africa, Asia, Europe, and North America. WNV was introduced into
the United States in 1999 and has spread by mosquitoes and birds throughout
the US and Canada. In 2006, over 4000 WNV infections were treated in the US,
with 174 fatalities reported. WNV is now a serious public health concern in
North America, and the current pattern of seasonal summer/fall epidemics is
likely to remain. There are are no human vaccines or antivirals that can be
used to control WN disease.
While 80% of people infected with WNV will remain
asymptomatic, 20% will develop the disease termed West Nile fever. Symptoms
include fever, headache, body aches, nausea, vomiting, and/ or skin rash.
These symptoms can last persist for a few days to several weeks. One in 150
people infected with WNV develop severe, even fatal, diseases of the nervous
system. West Nile encephalitis refers to an inflammation of the brain. West
Nile meningitis is an inflammation of the membrane around the brain and the
spinal cord. Severe WN disease symptoms include high fever, headache,
stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision
loss, numbness, and/or paralysis. Symptoms may last several weeks, although
neurological effects may be permanent. |
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