West Nile virus (WNV) is a viral disease that can cause encephalitis or meningitis, infection of the brain and the spinal cord or their protective covering. Prior to 1999, the disease was found only in Africa, Asia and southern Europe. Since 1999, WNV has spread throughout North America and has continued to cause disease in the United States. The yearly number of cases and fatalities has fluctuated depending on the weather conditions throughout the nation.
WNV is spread to people by the bite of an infected mosquito. The principal transmitter of WNV is the northern house mosquito (Culex pipiens). Mosquitoes first become exposed to the virus when they feed on birds that are infected with WNV. Once the mosquito is infected, it may transmit the virus to people or other animals when it bites them. Many birds can be infected with WNV, but crows and blue jays are most likely to die from the infection. Horses, too, are prone to severe WNV infection. People cannot get WNV from another person or from a horse that has the disease.
There is no vaccine currently available for WNV for people or most animals. However, there are vaccines available for horses, which represent 96.9 percent of all reported nonhuman mammalian cases.
WNV has become endemic in the United States and remains a serious disease threat; however, the number of cases and deaths vary significantly as climatic conditions vary by region from year to year. Sporadic seasonal epidemics will continue to occur in various regions of the country when weather and environmental conditions are most suitable. State, federal and local agencies continue to work together to address the health risks of WNV to Ohio families and their animals. Mosquito control efforts are often increased in urban areas during the summer to protect people from potential exposure to the disease.
Q. What should I do if I find a dead bird?
A. Priorities regarding disease surveillance change and vary by region from year to year. You may contact your state or local agencies or visit their website to determine if they are currently collecting and testing wild birds. Wildlife agencies routinely investigate sick or dead bird events if there is a specific priority of interest or if large numbers are impacted. If there is no ongoing testing, use a shovel or wear gloves and double-bag the bird in two plastic bags and dispose of it in the trash.
Q. What birds are of most concern regarding WNV?
A. Crows and blue jays are related and are especially susceptible to WNV infection. A dead bird that shows no other sign of injury or reason for death may have died from a WNV infection. Bird deaths have preceded outbreaks of this disease, so birds can be an early warning that WNV is present.
Q. Why are agencies typically no longer collecting and testing wild birds for WNV?
A. Most agencies are no longer testing for WNV because its presence is already known. WNV is now endemic, meaning it is well established and present throughout the United States. Resources and efforts are now better spent on management and control of disease spread. Surveillance efforts are typically most important for new and emerging diseases.
Q. Do I risk exposure to WNV by handling a dead bird?
A. There is no evidence that WNV is spread directly from dead birds to humans. However, health professionals advise that bare-handed contact with dead animals should always be avoided. Use a shovel or wear gloves when handling any dead animal.
Q. If I see a lot of crows roosting in an area, should I be concerned about WNV?
A. No, seeing crows alive and well is a good indication that the virus is not currently in your area. Dead crows, however, may indicate the presence of the virus.
Q. Are crows and blue jays the only birds affected by WNV?
A. No, but crows and their relatives (especially blue jays) are most likely to die. In previous outbreaks of WNV, large numbers of North American crows and other birds have been observed becoming ill and dying. Some exotic birds in zoos have also died. WNV has been identified in at least 200 species of free-ranging and captive birds found dead in the United States. Wildlife biologists have also found evidence that some healthy birds have been exposed to WNV and have survived.
Q. Are pet birds or poultry at risk for WNV?
A. Poultry do not seem to be seriously affected by WNV. Although, there is some evidence that pet birds have become ill from the virus, and infections without symptoms are possible. It is prudent to protect pet birds from biting mosquitoes.
Q. Can a dead bird pose a risk to my pet dog or cat?
A. To date, there is no evidence that a pet having any type of contact with a dead bird, including eating it, will develop WNV. There is evidence that a small number of dogs and cats have been infected with WNV, so you should protect your pet from biting mosquitoes. Eliminate stagnant water around your property: Regularly clean bird baths, drain water from old tires, and empty water-filled buckets and containers where mosquitoes might breed.
The Status of WNV in Ohio
WNV has been confirmed in Ohio every year since 2001. Infected mosquitoes, birds, horses and humans have been found in all Ohio counties. Therefore, the virus can be present throughout the state.
For the current status of WNV in Ohio and for more information, you can visit the following websites or contact your local health department.