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By Dot Sparer
dsparer@vet.uga.edu
Wildlife-disease researchers at the University of Georgia are spearheading efforts to find out what causes a mysterious brain disease that killed 13 bald eagles and several other birds last fall and winter in Georgia.
The primary suspect is avian vacuolar myelinopathy, or AVM, a disease that destroys a bird’s coordination and thus its ability to walk, swim or fly.
AVM has been confirmed in eight bald eagles, two Canada geese, a greathorned owl, several coots and a killdeer recovered at Clarks Hill Reservoir last November and December. Five eagles were too decomposed to provide useful diagnostic information.
Test results are pending on other birds that were examined in the laboratories of the Southeastern Cooperative Wildlife Disease Study. SCWDS, a teaching, research and field-service unit at the university, focuses on disease and health management of wildlife populations in 15 southeastern states.
“Under the microscope an affected eagle’s brain looks like lace,” says John Fischer, director of SCWDS and associate professor in the College of Veterinary Medicine. “It looks delicate but it’s devastating.”
Since eagles are a threatened species, 13 eagles comprise a fairly significant portion of the eagle population in the area.
“It’s unusual to find one dead bald eagle,” Fischer says. “Two would be a concern and 13 of them is a lot. It indicates there could be even more dead birds out there that have not been found.”
While the diagnosis of AVM has been made in four states, the cause of the disease has not yet been determined, despite intensive diagnostic and research investigations at SCWDS, the National Wildlife Health Center and other wildlifehealth institutions.
“Finding the cause of AVM is a high priority at SCWDS,” Fischer says. “Until we know the cause of the disease, we will not know how to prevent or treat AVM in eagles or other affected birds. Right now we think parasites or infectious agents such as bacteria and viruses are not involved. That would suggest that a most likely cause of AVM is a natural or man-made toxin. But we can’t rule anything out until we’ve determined the definitive cause of the problem.”
The disease was first found in bald eagles in Arkansas in 1994. That winter 29 bald eagles died in Arkansas and, two years later, the disease killed 26 more, as well as a number of American coots. In 1997, AVM was detected in coots in Georgia and North Carolina as well.
Fatal cases of AVM in eagles were first detected in Georgia, North Carolina and South Carolina in the winter of 1998.
Officials from the Centers for Disease Control in Atlanta believe AVM is not communicable to humans. But, as with any sick animal, birds suspected of having AVM or any other disease should be considered unfit for consumption.
Anyone who finds a dead or diseased eagle is urged to contact SCWDS at 542-1741. |
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