Avian Vacuolar Myelinopathy - FAQ
What is the cause
The exact cause of AVM is not known. Diagnostic, laboratory
and field work suggest a toxin, either naturally occurring
or man-made. Tests for a variety of compounds, including some known to
cause vacuolar myelinopathy, have been negative to date.There is no evidence
of bacterial, viral or parasitic infection.
Is AVM a prion
disease like bovine spongiform encephalopathy?
It is not currently
thought that AVM is a prion disease based on laboratory testing, the lesion
itself, and consultation with prion disease experts.
How are the birds
exposed to AVM?
The exact route of
exposure or intoxication is not known. It could be that eagles develop
AVM after ingesting affected coots or waterfowl, however all the species
affected may come in contact with the same disease agent independently
of each other.
What species have
been confirmed with AVM
- Bald eagles
- American coots
- Other - killdeer, great horned owl
What are the clinical
Affected birds may
have wobbly or uncoordinated flight and may crash land. Eagles have been
observed to fly into objects such as rock walls. On land, birds are unsteady,
walk with wings outstretched and appear "intoxicated". In the
water, coots and waterfowl have been observed swimming upside down, or
trailing a wing or leg. In general, affected birds are alert and aware
of their surroundings.
When does the disease
AVM typically occurs
between November and March, which is generally when the overwintering
avian populations migrate into and out of the area.
Where has this
As per diagnostic and research work conducted by USGS and SCWDS:
- Lakes De Gray, Ouachita, Hamilton and Greeson - within approximately
a 35 mile area of southwestern Arkansas.
- Lake Juliette (near Macon) and Strom Thurmond Lake (on Georgia/South
Carolina - Woodlake near the town of Vass
Carolina - L Lake and Par Pond on Savannah River Ecology Lab,
Lake Murray (near Columbia)
- Suspect cases occurred on Sam Rayburn Reservoir (in eastern Texas near