Birds become infected through the bite of an infected mosquito. Mosquitoes become infected when they feed on infected birds.
Infected mosquitoes can transmit West Nile virus to humans.
However, since birds can die of many different causes, finding a dead bird does not necessarily mean that the virus is present. No, West Nile virus is not spread directly from birds to persons. While the Department of Health is interested in collecting information about dead birds as part of its efforts to understand West Nile virus, we will not be picking up every dead bird reported. The Department will only be collecting a small sample of the bird population. However, we encourage New York City residents to report all dead bird sightings on this line to assist the department's monitoring efforts.