Auburn, Sept. 5, 2002 --- Wildlife biologists
and other scientists are in the middle of a third year of monitoring
Alabama's bird population for West Nile virus. In people, it can
cause West Nile encephalitis, a potentially deadly inflammation of
the brain. Last year, the state had its first two human cases of WNV.
This year, there have been six confirmed cases in Alabama.
"The virus is spread by mosquitoes that get the
disease from infected birds," says Ashley Lovell, who
coordinates the West Nile surveillance team in Alabama. "Birds
are the natural host for the virus, which can be fatal to birds,
horses, humans and other mammals."
Lovell, who is a wildlife biologist with the U.S.
Department of Agriculture's Wildlife Services program in Alabama,
says testing of dead birds is restricted to several species of birds
including crows, blue jays and raptors. Raptors found in Alabama
include hawks, eagles, ospreys and owls.
"Testing of dead birds began in May. Testing
has been limited to certain species because to date WNV has been
identified more frequently in these species," says Lovell.
Nationally, more crows have tested positive for WNV,
but in Alabama, more than 70 percent of the birds testing positive
for WNV in Alabama are blue jays.
"This may be related solely to how we receive
our samples of dead birds," says Lovell. "We get more
samples from Jefferson and other urban counties. Homeowners and
others in these areas are more likely to see jays than crows."
This year, more than 700 birds have been tested for
WNV. Slightly less than 50 percent of those tested positive for the
disease. In 2001, more than 770 dead birds were tested for WNV as a
result of the monitoring program. That's almost three times the
number tested in 2000.
In addition to monitoring the state's wild bird
population for the disease, scientists are also collecting mosquito
samples and examining them for the virus.
In 2001, nearly 125,000 mosquitoes collected in 22
Alabama counties were tested for WNV. That's double the mosquito
samples submitted for testing in 2000.
But scientists are not restricting their examination
of mosquitoes to WNV alone. In addition, they are also testing
mosquitoes for other forms of mosquito-borne diseases, including
Eastern equine encephalitis, St. Louis encephalitis and LaCrosse
encephalitis.
"The WNV surveillance effort is allowing us to
look for other potentially serious diseases as well," says
Lovell. "For example, EEE is much more serious and deadly than
WNV. "
The human case fatality rate from EEE is more than
30 percent, while it is about 15 percent or less for WNV.
Lovell says the mosquito examination is the most
time-consuming and labor-intensive part of the surveillance effort.
Mosquitoes must be sorted, identified by species and counted by
location. With as many as 6,000 mosquitoes in one collection, the
process takes a great deal of effort and man-hours.
"Extension as well as the Alabama
