Monitoring Alabama for West Nile Virus
19---Scientists are monitoring bird populations in Alabama for
the deadly West Nile virus (WNV). In 1999, seven people in New York
City died of encephalitis caused by WNV.
would seem far removed from a potential outbreak, but a wildlife
biologist with the U.S. Department of Agriculture's Animal and Plant
Health Inspection Service (APHIS) says that's not really the case.
"The virus is
spread by mosquitoes that get the disease from infected birds,"
says Ashley Rossi, who is coordinating the West Nile surveillance
team in Alabama. "It's believed that migrating birds play a
role in spreading the disease."
"The disease was
originally confined to New York, but by early last fall—the virus
had been identified in North Carolina. Birds are the natural host
for the virus, which can be fatal to birds and humans.
According to APHIS, the
virus has been confirmed in more than 4,300 birds from 80 species.
WNV can infect humans,
horses and wildlife. In people, it can cause West Nile encephalitis,
a potentially deadly inflammation of the brain. However, some people
who are infected may never know it, and others may only experience
mild flu-like symptoms or headaches.
It is estimated that as
many as 2500 people were exposed to WNV in the 1999 New York
outbreak but never developed any symptoms. That is because their
immune systems generated antibodies rapidly enough to prevent the
onset of symptoms.
Rossi says the
surveillance team needs the public's assistance with the project.
"The public can
help by identifying and if possible collecting dead birds for us to
examine," says Rossi. "We are looking for single dead
birds, in particular crows and bluejays."
Rossi says the public
should take some basic precautions in collecting the dead bird.
First, wear plastic
gloves or turn a large zipper-seal plastic bag inside out. Place
your hand in the bag and pick up the bird with your covered hand.
Then, grasp the edges of the bag and pull so it encloses the bird.
Seal the bag. Place the first bag in a second bag.
If possible, put the
sealed bag in a cooler with ice. Then take the sample to your county
Extension offices know how to get in contact with us to arrange
delivery of the sample," says Rossi. "When we receive the
sample, our scientists will conduct necropsies to determine if West
Nile virus is present. Last year, we tested 280 birds."
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 2000, more than 60,000 mosquitoes were collected
in Alabama alone.
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 LaCross Encephalitis.
surveillance effort is allowing us to look for other potentially
serious diseases as well," says Rossi. "While WNV hasn't
been found in Alabama yet, these other diseases already occur here.
For example, Eastern Equine Encephalitis is much more serious and
deadly than WNV. "
Rossi says the mosquito
examination is the most time-consuming and labor-intensive part of
the surveillance effort. Mosquitoes must be sorted, identified by
its species and then frozen for later analysis.
"Extension as well
as the State Department of Public Health among others are all vital
partners in the surveillance effort," says Rossi. "The
surveillance effort is far too broad to be accomplished without the
work of people in a number of cooperating agencies."
You can reduce the
possibility of exposure to mosquito-borne diseases in several ways.
First, reduce mosquito-breeding sites by eliminating stagnant water
in which mosquitoes can breed. Turn over plastic wading pools or
wheelbarrows when not in use.
Aerate ornamental pools
or stock them with fish. You can also use products such as mosquito
dunks to control mosquitoes in the pond. These control mosquito
larvae and do not harm fish. You can find them in pet stores or
stores that sell pond supplies.
Clean and chlorinate
swimming pools that are not in use.
You can continue your
outdoor activities, but you should reduce your risk of being bitten
Make sure windows and
doors have screens that are in good repair. Minimize time spent
outdoors between dusk and dawn. Wear shoes, socks, long pants and a
long-sleeved shirt when outdoors for long periods of time or when
mosquitoes are most active.
You may want to use a
mosquito repellent, applied according to label directions, when you
SOURCE: Ashley Rossi,
Wildlife Biologist, USDA Animal and Plant Health Inspection Service