The mysterious brain disease responsible for the deaths of bald eagles and American coots in Arkansas has now been found in two species of ducks discovered dead at Woodlake, North Carolina, and in bald eagles and coots from three other southeastern states. According to a USGS wildlife disease specialist, this is the first time the new disease, called avian vacuolar myelinopathy, has been documented in species other than American coots and bald eagles.
Pathologists at USGS's National Wildlife Health Center in Madison, Wisconsin, and the Southeastern Cooperative Wildlife Disease Study (SCWDS) at the University of Georgia have confirmed that bald eagles collected from four new locations (near Woodlake, North Carolina; Aiken, South Carolina; and Strom Thurmond Lake and Lake Juliette, Georgia) and coots from Aiken, South Carolina, died from the same brain disease that has killed at least 58 bald eagles in Arkansas and an unknown number of coots in Arkansas, North Carolina and Georgia.
The disease affects the brain and spinal cord by damaging the myelin sheath that insulates the nerve fibers. It is diagnosed by microscopic examination of very fresh brain and spinal cord tissue. Dr. Nancy Thomas, the USGS pathologist who first described the lesion, explained that "In affected birds the disease appears as open spaces in the white matter of the brain." When the coating surrounding the myelin is damaged, Thomas said, "Communication in the nervous system is impaired, causing a bird to become uncoordinated or paralyzed." Thomas used an electron microscope to determine that the spaces are caused by separation of the myelin layers that surround nerve fibers. Using the same techniques, Dr. John Fisher, a SCWDS pathologist, confirmed the lesion in a North Carolina mallard and ringnecked duck, and a Strom Thurmond Lake bald eagle.
USGS wildlife disease specialist Dr. Kimberli Miller said that afflicted birds
typically fly erratically or are unable to fly; t
Contact: Kim Miller
United States Geological Survey