West Nile virus (WNV) is an infectious disease that first appeared in the United States in 1999. The virus can infect humans, birds, mosquitoes, horses and some other mammals. The virus is transmitted to humans by mosquitoes.
Most human infections are mild, causing fever, headache, and body aches, often accompanied by a skin rash and swollen lymph glands. If the virus crosses the blood-brain barrier, however, it can cause life-threatening conditions that include inflammation of the brain and spinal cord.
If West Nile virus enters the brain, however, it can be deadly. It may cause inflammation of the brain, called encephalitis, or inflammation of the tissue that surrounds the brain and spinal cord, called meningitis.
WNV is not spread through casual contact such as touching or kissing a person with the virus.
Older people are most at risk. There are no specific vaccines or treatments for human WNV disease. The easiest and best way to avoid WNV is to prevent mosquito bites:
-- apply insect repellent to exposed skin
-- get rid of mosquito breeding sites by emptying standing water from flower pots, buckets and barrels
-- stay indoors between dusk and dawn, when mosquitoes are most active
-- use screens on windows and doors to keep mosquitoes out
-- check for clogged rain gutters and clean them out
-- remove discarded tires, and other items that could collect water
-- any object or structure where stagnant water can collect is potentially a mosquito breeding habitat
Currently there is no vaccine available to protect humans from West Nile virus.
People over the age of 50 are more likely to develop serious symptoms of WNV if they do get sick and should take special care to avoid mosquito bites.
Repellents with DEET can be used for both adults and children, according to directions.
Pregnant women should protect themselves when outdoors by using a mosquito repellant that contains DEET or picaridin.
Mosquito control activities do not eliminate every mosquito, so personal protection is still important.