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West Nile Virus in Pennsylvania 


West Nile virus (WNV) is most commonly transmitted to humans by mosquitoes. You can reduce your risk of being infected with WNV by using insect repellent and wearing protective clothing to prevent mosquito bites. There are no medications to treat or vaccines to prevent WNV infection. Fortunately, most people infected with WNV will have no symptoms. About 1 in 5 people who are infected will develop a fever with other symptoms. Less than 1 percent of infected people develop a serious, sometimes fatal, neurologic illness. (information provided by CDC).


For the most up-to-date information on West Nile Virus in Pennsylvania, please visit

What is Pennsylvania doing to reduce the risk to its citizens?
  •  DEP staff is monitoring mosquito populations statewide and spraying in areas with mosquito larvae to reduce the threat to the public
  • Spraying is determined on a monitoring basis of (mosquito) populations and is done on an 'as-needed' basis.
  •  DEP can speak in further detail about this
  •  Pennsylvania has a  West Nile Virus Control Program (a plan for controlling West Nile virus for the WNV season)
  •  The mission of the program is to reduce expected morbidity and morality, health care costs, and financialimpact that WNV disease outbreaks would have upon PA industry i.e., Agriculture, Fishing, Hunting, Tourism, etc.).
  • The DOH along with DEP and Ag have developed and implemented a coordinated and comprehensive strategy to prevent and control the seasonal impact of WNV in Pennsylvania.
  •  The multi-agency team, tasked with reducing the impact of WNV in the state, includes county commissioners, health departments, conservation districts, emergency services and the Penn State Cooperative Exstension Service.
  • There is a tight data sharing using a WNV database maintained by DEP, as well as physical transfer of samples, among the organizations.

 WNV Activity & Surveillance In Pennsylvania




In 2014, 39 counties in Pennsylvania found positive tests for West Nile virus. There were 13 positive cases of West Nile virus in humans. As of 08/28/2015, there have been 7 human cases in Pennsylvania for 2015.
What are symptoms of WNV?
Approximately 80 percent of infected people do not show any symptoms of disease.
Up to 20 percent have fever, head and body aches, vomiting, swollen glands and/or skin rash. Less than 1 percent  develop severe illness to include encephalitis with blindness, coma, convulsions, headache, high fever, muscle weakness, neck stiffness, numbness, paralysis, and/or tremors.
Symptoms may last for weeks, and the neurological effects may be permanent and severe.
Mild symptoms of resolve on their own, but more serious symptoms such as:
  •  high fever
  •  severe headache
  • visual disturbances
  •  stiff neck
  • altered mental status or disorientation should be immediately evaluated by a health care provider
  • No vaccine ot specific antiviral treatments for West Nile virus infection are available.
  • Over-the-counter pain relievers can be used to reduce fever and relieve some symptoms.
  • In severe cases, patients often need to be hospitalized to recieve supportive treatment, such as intravenous fluids, pain medication, and nursing care in severe cases, patients often need to be hospitalized to recieve supportive treatment, such as intravenous fluids, pain medication, and nursing care.

What precautions can people take?

 As there is no human WNV vaccine, the best protection available is to prevent mosquito bites.

  •  All should routinely wear mosquito repellent while outdoors during the mosquito season.
  •  Especially during dusk and dawn when many mosquito species are actively blood feeding.
  •  The repellent should contain DEET and be applied following the manufacturer's directions.
  •  Install or repair screens on windows and doors. If you have it, use your air conditioning.
    •     Help reduce the number of mosquitoes around your home. Empty standing water from containers such as flowerpots, gutters, buckets, pool covers, pet water dishes, discarded tires, and birdbaths.ff


Who is at risk for serious illness if infected with West Nile virus?
Serious illness can occur in people of any age. However, people over 60 years of age are at the greatest risk for severe disease. People with certain medical conditions, such as cancer, diabetes, hypertension, kidney disease, and people who have received organ transplants, are also at greater risk for serious illness.
For more information about West Nile Virus on a national level, please visit the CDC website at