SALT LAKE CITY — The mystery illness that killed 27 bald eagles in Utah in December appears to be West Nile Virus, state officials said Tuesday.
The Utah Division of Wildlife Resources said in a statement that laboratory tests done on some of the first birds found indicate they died from the virus.
Since Dec. 1, officials have found the birds in northern and central Utah. All were either dead or were ill and later died during treatment. The eagles displayed similar symptoms, including head tremors, signs of seizures, weakness in legs and feet, and a paralysis of the bird's wings.
The birds do not pose a risk to human health. Beyond the 27 that have died, officials said five eagles were being treated at a wildlife rehabilitation center Tuesday.
Utah wildlife officials aren't sure how the eagles caught the virus, but they suspect the birds contracted it by eating eared grebes that were infected with the virus and died recently.
West Nile Virus, which is spread by mosquitoes, usually infects eagles and other birds during warmer months.
Mark Hadley, a Utah Division of Wildlife Resources spokesman, said the grebes, a duck-like aquatic bird, start arriving in Utah in October, when mosquitoes are still active. He said it's possible that after the grebes were bitten, it took awhile for them to die and be eaten by the eagles.