West Nile Virus Fast Facts

PHOENIX - AUGUST 5: A culex tarsalis female mosquito that was caught in a trap will be tested for the presence of the West Nile virus at the Arizona Department of Health Services laboratory on August 5, 2004 in Phoenix, Arizona. (Photo by Jeff Topping/Getty Images)

(CNN)West Nile virus (WNV) is primarily transmitted to humans by infected mosquitoes.

About 2,000 people have died of West Nile virus in the United States since it was first detected in New York City in 1999.
West Nile virus symptoms explained
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Facts:
West Nile virus is usually spread through the bite of infected mosquitoes.
It is not spread person-to-person through casual contact.
In rare cases, WNV can be spread through blood transfusions, organ transplants, exposure in a lab setting or from mother to infant.
Symptoms of West Nile infection include: fatigue, fever, headache, body aches, rash and swollen lymph nodes.
70%-80% of infected people do not display any symptoms.
According to the CDC, less than 1% of infected people develop a serious neuroinvasive illness, such as encephalitis (inflammation of the brain) or meningitis (inflammation of the protective membranes covering the brain and spinal cord).
There is no vaccine or specific treatment for WNV.
The most effective method of prevention is to avoid mosquito bites, by using insect repellent and by wearing protective clothing when outdoors.
1937 - The first case of West Nile virus is reported in Uganda. It is common throughout Africa, Central Asia and the Middle East.
August 1999 - The first cases of West Nile encephalitis in the Western Hemisphere are reported in the Bronx and Queens boroughs of New York City. It is not known how the virus arrived in the United States.
Statistics: (source: Centers for Disease Control and Prevention)
2016 (prelim) -
2,038 cases of WNV were reported in 45 states and the District of Columbia, with 94 deaths.
2015 - 2,175 cases of WNV were reported in 44 states and the District of Columbia, with 146 deaths.
2014 - 2,205 cases of WNV were reported in 44 states and the District of Columbia, with 97 deaths.
2013 - 2,469 cases of WNV were reported in 47 states and the District of Columbia, with 119 deaths.
2012 - 5,674 cases of WNV were reported in 48 states, Puerto Rico and the District of Columbia, with 286 deaths.
2011 - 712 cases of WNV were reported in 43 states and the District of Columbia, with 43 deaths.
2010 - 1,021 cases of WNV were reported in 40 states and the District of Columbia, with 57 deaths.
2009 - 720 cases of WNV were reported in 37 states and the District of Columbia, with 32 fatalities.
2008 - 1,356 cases of WNV were reported in 45 states and the District of Columbia, with 44 fatalities.
2007 - 3,630 cases of WNV were reported in 43 states, with 124 fatalities.
2006 - 4,269 cases of WNV were reported in 43 states and the District of Columbia, with 177 fatalities.
2005 - 3,000 cases of WNV were reported in 43 states and the District of Columbia, with 119 fatalities.
2004 - 2,539 cases of WNV were reported in 41 states and the District of Columbia, with 100 fatalities.
2003 - 9,862 cases of WNV were reported in 45 states and the District of Columbia, with 264 fatalities.
2002 - 4,156 cases of WNV were reported in 39 states and the District of Columbia, with 284 fatalities.
2001 - 66 cases of WNV were reported in 10 states, with 10 deaths.
2000 - 21 cases of WNV were reported in Connecticut, New Jersey and New York, with two fatalities.
1999 - 62 cases of WNV were reported in New York state, with seven deaths.