I keep seeing dead birds on the sidewalks and in the streets around my neighborhood. Should I be concerned?
Probably not. Since its introduction into North America in 1999, the early presence of West Nile virus (WNV) in an area has sometimes been indicated by dead wild birds. WNV can be transmitted to birds via the bite of an infected mosquito. The bird species most adversely affected by WNV include crows, blue jays and predators, such as hawks and owls. The species of bird you are seeing dead in the streets is important. If the dead birds are mostly crows, increased WNV in your area is likely. If you are seeing mostly sparrows and pigeons, increased local transmission of WNV is unlikely. If WNV is not the culprit, there could be many other reasons for the dead birds you see, including pesticides, diseases such as avian botulism and the increased natural mortality associated with spring and autumn migration. If the dead birds you have observed are associated with increased WNV transmission, there will be other factors that are routinely monitored by mosquito control and public health officials in your area. For example, sentinel chickens are used in many parts of the US to detect and monitor WNV transmission. Chicken flocks are placed in the field where a weekly blood sample is analyzed for antibody to WNV and other mosquito-borne viruses. A positive antibody test indicates that the chicken was bitten recently by an infected mosquito. In some areas, mosquitoes are collected and tested by public health officials for WNV. If there is an increased level of WNV transmission in the area where you live, the media will be alerted and Public Service Announcements released. Most people who are infected with WNV have no symptoms and recover completely, but one in five will develop a fever and other symptoms, such as headache, joint pain or vomiting. In rare cases, WNV can cause a serious neurological condition such as encephalitis or meningitis (inflammation of the brain or surrounding tissue) or even death. The risk for WNV transmission depends on where you live and whether there is a history of WNV transmission in your area. For example, WNV transmission is more common in and around Chicago than in other parts of Illinois. It would be helpful for you to report dead bird observations to your local public health department, including where and when you saw the bird along with its species. Finally, avian mortality is common, and I suspect that you should not be overly concerned about any dead birds you see. Report the bird’s exact location to the local agency that monitors WNV in your city and, if necessary, a representative from that agency will collect the bird for further analysis. Important: If you don’t get a response from your local authorities, you should not handle a dead bird with your bare hands. To avoid the possible spread of disease, wear disposable gloves and place the bird in a plastic bag and tightly close it before putting it in a garbage can.