West Nile Virus

What is West Nile Virus? Previously found only in parts of Europe, Asia, and Africa, West Nile Virus was first found in the United States in 1999. The virus was probably introduced into this country by an infected mosquito or bird.

WNV is a disease transmitted by mosquitoes to mammals, birds and humans. A mosquito infected with WNV may infect a bird when taking a blood meal from that bird. Other mosquitoes can then pick up the virus from the infected bird. Other animals, including horses, and people can become infected when bitten by a mosquito that is carrying the virus.

In a very small number of cases, WNV also has spread through blood transfusions, organ transplants, breastfeeding and even during pregnancy from mother to baby. WNV is not spread through casual contact such as touching or kissing a person with the virus.

What are the symptoms? WNV can cause encephalitis, or inflammation of the brain, in susceptible animals and people.  People with mild infections may experience fever, headache, body aches, skin rash and swollen lymph glands.  More severe infections may experience high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions and paralysis.

Who is most at risk? People over 50 years of age have the highest risk of developing a severe illness because as we age, our bodies have a harder time fighting off disease.  People with compromised immune systems are also at increased risk.  However, anyone can get the virus.

Birds and horses are the animals most likely to develop illness from infection with WNV. Crows are especially susceptible, and most crows that are infected become sick and die. Raptor populations have also been hit hard in many locations.

Not all horses that become infected actually get sick. In horses that do become ill, symptoms can range from mild depression and lethargy to signs of severe neurologic disease.

WNV has been diagnosed in other animals, including dogs and cats. Most of these animals did not show any signs of illness after infection.

Is there treatment? There is no specific treatment for WNV infection, only supportive care.  While most people fully recover from the virus, in some severe cases, a patient may need to be hospitalized.

What do I do if I find a sick bird? Call your local wildlife rehabilitator as soon as possible. Many birds, especially raptors have survived the disease and have been released.

Prevention:Only a few of the approx. 60 different species of mosquitoes in PA. carry WNV.  Mosquitoes lay their eggs in stagnant water.  Weeds, tall grass, shrubbery and discarded tires also provide an outdoor home for adult mosquitoes.  By eliminating breeding places, we can help reduce exposure to the virus.

  • Dispose of outdoor cans, pots, and other containers that may hold water
  • Remove discarded tires
  • Turn over wading pools when not in use
  • Clean and chlorinate swimming pools when not in use
  • Remove leaves and debris from roof gutters
  • Aerate ornamental pools or add fish to the pools
  • Drill holes in the bottom of outdoor recycling containers
  • Turn over or remove buckets and wheelbarrows that could collect water
  • Flush and clean water troughs at least every 4 days
  • Use landscaping to eliminate standing water
  • Report unexplained dead birds to the Pennsylvania Department of Health

Remember:Mosquitoes can multiply in any water puddle that lasts more than 4 days.
How can I protect myself? It is not necessary to limit any outdoor activities, unless local officials advise you otherwise, however, you can and should try to reduce your risk of being bit­ten by mosquitoes. In addition to reducing stagnant water in your yard, make sure all windows and doors have screens, and that all screens are in good repair.

This information was gathered by Red Creek Wildlife Center From the following sources:
Pennsylvania State Departments of:

Conservation and Natural Resources
and the Pennsylvania Game Commission