West Nile Virus

Cumberland County participates in the PA DEP West Nile Surveillance Program, which aims to prevent transmission and outbreaks of WNV.  The Pennsylvania WNV Program is now a proud member of the Pesticide Environmental Stewardship Program (PESP).  The program uses an Integrated Pest Management (IPM) Plan to control mosquitoes while limiting the effects on people and the environment.  IPM is a science driven, holistic approach focused on long-term prevention using a combination of techniques including:
  1. Education- Disseminating information to residents and municipalities about habitat reduction and bite avoidance.
  2. Surveillance- Collecting, trapping, and identifying mosquitoes to test for WNV. Responding to complaint calls.
  3. Source Reduction- Removal of artificial containers and man-made habitat.
  4. Larval Control- Treat waters which are breeding grounds to prevent larval mosquitoes from emerging as adults.
  5. Adult Control- Last mode of action.  Evening spray events for adult population control.
West Nile Virus Biology
West Nile virus (WNV) is transmitted to humans after an infected female mosquito takes a blood meal.  WNV does NOT spread from person to person. In nature, WNV cycles between birds and mosquitos.  Humans and horses are incidental hosts of the virus. Since the virus cannot complete its lifecycle within incidental hosts, they are also called "dead end" hosts.
Virus transmission cycle
West Nile Virus  
Most people who contract WNV will be asymptomatic, while about 20% of people will develop a mild case of WNV fever.  Approximately 1% of people with WNV will develop severe symptoms from the infection becoming neuroinvasive (attacking the brain or nervous tissue).

While anyone can contract WNV, people over 50 years of age have the highest risk of developing severe illness, as the body has a harder time fighting off disease with age.  People with compromised immune systems, cancer, diabetes, hypertension, and kidney disease are also at higher risk of developing a severe form of WNV infection.

What are the symptoms?
Mild infections are common and include fever, headache, and body aches, often with skin rash and swollen lymph glands. Headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, occasional convulsions, and paralysis mark more severe infection.   

West Nile Encephalitis

West Nile encephalitis (an inflammation of the brain) is caused by West Nile virus. It is a neuroinvasive version of WNV infection and requires medical attention.  
There is no specific therapy. In mild cases, symptoms can be treated with fluids and rest.  In more sever cases, hospitalization and intensive supportive therapy may be needed.  

A healthcare provider should be consulted if someone believes they have contracted WNV.

Avoid WNV by not getting bit by mosquitoes
  • Wear repellants, long sleeves, and pants
  • Take extra precaution around dusk, the peak of female mosquito feeding
  • Remove mosquito breeding habitats around the yard
  • Secure window screens and doors so the mosquito can't find a way into houses


  • In New York City in 1999, seven of the 60 people infected died from the virus. 
  • According to the CDC, 9% of patients who contracted Neuroinvasive WNV died in 2012.
  • In 2015, there were 1,732 cases of WNV infection, with 94 deaths.
    • In Pennsylvania, there were 30 cases with one death.
    • These statistics do not include the large number of people who had minor flu like symptoms and did not seek medical treatment.

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