| August
5, 2002
Little
Rock—The
Arkansas Department of Health today submitted a human
blood sample to the Centers for Disease Control and
Prevention (CDC) for confirmatory testing for the West
Nile virus. This
is the only suspected human case of West Nile virus in
the state. It
occurred in Union County.
The department expects an answer on the tests
later this week.
West
Nile virus is transmitted by infected mosquitoes biting
humans, horses and other animals after feeding on
diseased birds, which are the host animals.
Not all mosquitoes have a virus in them, but
certainly, the more mosquito bites one gets, the greater
the risk of catching a disease.
Most people that get bitten by an infected
mosquito do not get sick or only show very mild or no
symptoms. Symptoms
of human West Nile virus infections typically begin
within 14 days following the insect bite and consist of
fever, muscle and joint aches, listlessness, and in most
severe cases, headaches leading to encephalitis
(inflammation of the brain).
Less than one percent of persons infected with
West Nile virus will develop severe illness, according
to CDC. Of
those one percent with severe illness, death rates range
from three to 15 percent and are highest among the
elderly. Also
at risk are persons with weakened immune systems.
There is no specific treatment for West Nile
virus infection; avoiding mosquitoes is the best
prevention.
Additionally,
27 birds have tested positive at the Arkansas Livestock
and Poultry Commission Laboratory, and 10 of these birds
have been submitted to CDC and National Wildlife Health
Center for confirmatory testing for West Nile virus.
The first bird confirmed positive for the virus
in 2002 was in St. Frances County.
The total number of Arkansas birds found positive
for West Nile virus in 2001 was four in Sebastian, Union
and Saline counties.
The
Livestock and Poultry Commission is reporting two
presumptive cases of West Nile virus in Arkansas horses,
with samples being sent for confirmatory testing to the
National Veterinary Services Lab in Ames, Iowa.
Horse owners should consider vaccinating their
horses for West Nile virus. Although it is not yet known
what degree of protection vaccination will provide, it
is the only mechanism that owners have to potentially
protect their animals, beyond reducing exposure to
mosquitoes. Vaccine
manufacturers recommend that horses receive at least two
doses three to four weeks apart, followed by an annual
booster. There
is no West Nile virus vaccine for humans.
Fay
Boozman, M.D., ADH director, says, “We thank the
public who has been so helpful in finding dead birds and
in submitting them for testing.
Arkansans should continue to put dead crows and
Blue Jays in sealed plastic bags and take them to their
local health unit, so testing of these birds can be
arranged. Birds
which have begun decomposing do not test well, so if the
dead birds are infested with ants or maggots, they are
not suitable for determining the presence of West Nile
virus.”
Other
Mosquito-borne Illnesses
The
Arkansas Department of Health is continuing its
surveillance for mosquito-borne viruses in Arkansas and
is coordinating testing of birds, horses and mosquitoes
with the Arkansas Livestock and Poultry Commission.
Other specific mosquito-borne viruses include Eastern
Equine Encephalitis and St. Louis Encephalitis (which,
similar to West Nile virus, can be transmitted from
diseased birds to mosquitoes).
According
to the Livestock and Poultry Commission, two horses have
tested positive for Eastern Equine Encephalitis.
“Humans, horses, pheasants, and emus are all
very susceptible to Eastern Equine Encephalitis,” said
Conley Byrd, DVM, state veterinarian, with the
Commission. “Horses
are not able to develop sufficient levels of the virus
to transmit the disease to other horses or humans.
Infection in horses does indicate that
there are infected birds in the area and people should
take precautions to reduce the possibility of being
bitten by mosquitoes.”
Eastern
Equine Encephalitis is considered the most severe
mosquito-borne encephalitis; and, the fatality rate can
approach 70 percent.
Children are the most likely to have serious
illness. Symptoms
of human Eastern Equine infection typically begin within
14 days following the insect bite and consist of fever,
muscle and joint aches, listlessness, and in most severe
cases, headaches leading to encephalitis (inflammation
of the brain). There is no Eastern Equine Encephalitis
vaccine for humans.
Arkansas
is seeing Eastern Equine Encephalitis a couple of weeks
earlier than normal, Byrd said.
The diagnosis of this disease, in horses that
have not been vaccinated, is not unusual for mid-August
through October. Horses
that exhibit symptoms of Eastern Equine Encephalitis do
not normally recover.
Early symptoms, such as not eating and feeling
listless, can be confused with other diseases such as
colic and may quickly be followed by death.
It is suggested that owners consult with their
veterinarians if their horses show any sudden or unusual
symptoms. Owners
who have not previously vaccinated their horses for
Eastern Equine Encephalitis should do so; it is
recommended that horses receive at least two doses two
to four weeks apart.
St.
Louis Encephalitis does not cause disease in animals; it
is strictly a human disease. Arkansas experiences
sporadic cases of St. Louis Encephalitis.
The largest outbreak in recent years was in 1991
in Jefferson County, with 28 hospitalized and five of
those, all over the age of 60, resulting in death.
In
2001, there were two cases of St. Louis Encephalitis,
resulting in one death in Jefferson County. Most people
experience flu-like symptoms. Those most at risk are the
elderly.
Public Response
“First
and foremost, the public should take precautions,”
Boozman said. “The
most prudent response is prevention because there is
only symptomatic treatment for these diseases.
The surest way to stop the spread of these
mosquito-borne diseases is prevention, and every
household can take action.”
Mosquitoes
can breed in any body of water, from small containers
such as tires and tin cans, to large bodies of water
like lakes or marshes. These breeding places create a variety of mosquito problems.
To help stop mosquitoes from breeding, Arkansans
should:
-
Dispose of tin cans, plastic containers, ceramic pots or
similar water-holding containers.
-
Remove all discarded tires on your property.
-
Drill holes in the bottoms of recycling containers that
are kept outdoors. Make sure roof gutters drain properly
and clean clogged gutters in the spring and fall.
-
Turn over plastic wading pools and wheelbarrows when not
in use. Change the water in bird baths.
-
Clean vegetation and debris from the edges of ponds.
-
Clean and chlorinate swimming pools, outdoor saunas and
hot tubs.
-
Drain water from pool covers.
-
Use landscaping to eliminate stagnant water that
collects on your property.
The
following protective measures are recommended:
Make
sure all windows and doors have screens in good repair.
Stay indoors when mosquitoes are more active,
usually at dawn and dusk.
When it is necessary to be outdoors, wear
protective clothing and use mosquito repellent
containing up to 35 percent DEET
(N,N-diethyl-meta-toulamide).
Use
the following precautions when using repellents
containing DEET:
- Store
out of the reach of children and read all instructions
on the label before applying.
-
Do not allow young children to apply DEET themselves.
-
Do not apply DEET directly to children. Apply
to your own hands and then put it on the child, avoiding
the child’s face and hands.
-
Avoid prolonged and excessive use of DEET.
-
Do not apply repellents in enclosed areas.
-
Do not apply directly to your face.
-
Wash all treated skin and clothing after returning
indoors.
If
you believe you or your child is having an adverse
reaction to a repellent containing DEET, wash the
treated area immediately and call your health care
provider.
The
Health Department is continuing to monitor the state
with regard to mosquito-borne diseases. The
ADH has established a West Nile virus hotline to respond
to public inquiries.
If you have a question, please call 501.280.4817
from 8:00 a.m. through 4:30 p.m., Monday through Friday.
For after hours and weekends, please call
501.661-2136 or 1.800.554.5738.
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