Bald eagles started dying in early December in Utah, and by early January of this year there were 40 confirmed deaths of the majestic birds. Although West Nile Virus (WNV) from the beginning was the suspected killer, until the virus was positively identified wildlife officials were unsure because the virus had never been reported so late in the year.

WNV is transmitted by the bites of infected mosquitoes, and birds serve as important carriers of the virus. Infected mosquitoes transmit the virus to birds when they bite them, and then more mosquitoes become infected with the virus when they bite infected birds. Some bird species are much more susceptible than others. This is the first time so
many bald eagles have died from the virus.

No new dead bald eagles were discovered after early January, so it seems that the main season when WNV was being transmitted to the eagles has ended for now.

WNV is a serious mosquito-transmitted virus first discovered in New York City in 1999, but now has been reported throughout the continental United States. If an infected mosquito bites a person, most people exhibit no symptoms, but some develop a fever and flu-like symptoms, and a small percentage of people infected with WNV die every year. Most cases of WNV occur from June to September.