FEATURE - West Nile virus takes toll on US birds
Date: 20-Sep-02
Country: USA
Author: Karen Pierog
"The crows usually are there and get the first dibs on the
peanuts," she said.
In early August, the crows disappeared. Then Anderson
noticed the blue jays started looking sick, followed by
house finches and goldfinches, chickadees, and most recently
she found a dead mourning dove, all apparently victims of
the West Nile virus.
"I loved the crow family that lived in my yard," Anderson
said. "I think they're dead."
The virus, blamed for dozens of human deaths and more than
1,500 cases of illness, is also taking a toll on avian
wildlife in a wide section of the country from Minnesota
south to the Gulf of Mexico and from Nebraska east to Ohio,
experts say.
A September survey by the National Audubon Society's Chicago
region found that crows, which are normally noisy and
visible birds, are almost completely absent from parts of
the Chicago area. Audubon Monitors also reported unusual
numbers of dead or ill birds of many species.
"For people who really love nature, this is really upsetting
to them to see this," said Judy Pollock, the Audubon's bird
conservation projects manager.
Birds serve as the host for the West Nile virus, which is
spread by mosquitoes to other birds, as well as to humans,
horses, squirrels and even canines. The virus, which causes
encephalitis, a potentially fatal inflammation of the brain
and spinal cord, cannot be spread from person to person or
from birds to humans.
A DEADLY DISEASE
Illinois has emerged as the epicenter so far this year for
West Nile infections among humans with 457 cases reported as
of Thursday, 23 of them fatal, according to state officials.
The U.S. Centers for Disease Control and Prevention reported
the disease has been seen in most of the continental United
States with 1,641 cases of human infection and 80 deaths.
West Nile, which was spotted on the East Coast three years
ago, has taken an even bigger toll on birds, with more than
100 species known to be susceptible to the disease.
The virus, which was initially seen mostly in crows and blue
jays, has spread to birds of prey or raptors, including
hawks, owls and eagles.
An eagle raised in captivity for 12 years at the Bay Beach
Wildlife Sanctuary in Green Bay, Wisconsin, succumbed to the
virus about three weeks ago.
"It's hard to lose a bird that you've had so long," said
Mike Reed, the sanctuary's curator.
Dr. Pat Redig, director of The Raptor Center at the
University of Minnesota, said the center got its first West
Nile virus case on Aug. 23 in a great horned owl. Since then
another 40 or so raptors, mostly great horned owls and
red-tailed hawks, have come into the center with the
disease. Most of the birds died or were euthanized,
according to Redig.
Raptor deaths from the disease have also been reported in
Illinois, Indiana, Kentucky, Louisiana, Michigan, Missouri
and Nebraska. In Ohio, the disease is suspected in the
illness or death of 800 to 1,000 raptors.
"I've been doing this for 30 years and I've never seen
anything like this before in wild birds," Redig said.
He said the birds first appear unaware of their
surroundings, then lose their ability to stand and eat and
finally begin to suffer from tremors and blindness and
sometime seizures.
With no specific anti-viral treatment available, the center
has been using intravenous fluids, stomach feeding tubes and
anti-inflammatory non-steroid drugs to treat birds in the
first two stages of the disease.
SEARCH WIDENING
Redig said the center was exploring whether the disease
could infect raptors in ways other than through mosquitoes,
including whether the virus could be transmitted through a
digested meal, taking into account that great horned owls
eat crows that might carry the disease.
Other areas being examined included if transmission could
occur through parasitic flies and whether a vaccine
specifically for birds can be developed.
Experts said while West Nile was
