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West Nile Virus

westnilevirus West Nile virus (WNV) is a potentially serious illness transmitted by mosquitoes to people. The virus survives in nature in birds and is passed when a mosquito feeds on an infected bird. The infected mosquito can then pass the virus when it bites humans and other mammals, such as horses. Most persons (80%) who become infected with the virus will not become ill. However, for the small proportion who do become sick (20%), symptoms can include fever, headache, rash, muscle weakness, nausea, and vomiting. A very small proportion (1%) may develop neurological symptoms such as limb paralysis, tremors, and altered mental status.  In rare cases, WNV can be fatal.

WNV cannot be passed from person to person, only from the infected mosquito to a person.  Many people who are diagnosed with WNV do not remember being bitten by a mosquito.  Treatment for WNV is typically supportive care as most illnesses resolve on their own.

Before 1999, when it was detected in New York City, WNV was found in Africa, Asia, Europe, Middle East, and Australia. Since then, the virus has spread throughout the United States as well as other parts of North America. The first human cases of WNV reported in Kern County were in 2004.  Since then, more than 400 cases have been diagnosed in Kern County residents.

While there is a vaccine against WNV for horses, there is no vaccine available for people. The best prevention against WNV is avoiding mosquito bites.  To decrease your risk of mosquito-transmitted infections:

  • Avoid mosquitoes at all times of the day.
  • Avoid mosquito-infested areas and use mosquito repellant on exposed skin.
  • Wear long-sleeved shirts and long pants whenever you are outdoors.
  • Do not allow water to collect and stagnate in old tires, flowerpots, fountains, birdbaths, pet bowls, or other containers.  These are prime breeding grounds for mosquitoes.
  • Keep swimming pools operating properly; drain water from pool covers.
  • Stock garden ponds with fish that eats mosquito larvae such as gambusia, goldfish, and others.
  • Empty and scrub the walls of birdbaths and wading pools weekly to remove any attached mosquito eggs.
  • Make sure that doors and windows have tight-fitting screens in good repair to keep mosquitoes out of your home.
West Nile Virus Activity in Kern County (updated 9/13/2018)

 


2007


2008


2009


2010


2011


2012


2013


2014


2015


2016


2017


2018


Human Cases


140


2


19


15


18


25


25


11


11


17


30


3


Dead Birds


124


10


28


13


4


14


2


3


1


0


3


0


Mosquito Pools


203


7


138


277


389


571


181


111


135


80


152


44


Sentinel Chickens


82


18


104


86


140


74


12


0


0


0


0


0

 

WNV Map  2018.9.13

Additional Resources:
http://www.westnile.ca.gov/
http://www.westnile.ca.gov/wnv_faqs_basics.php
http://www.cdc.gov/westnile/prevention/index.html
http://www.cdc.gov/westnile/

WNV Strategic Response Plan