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WEST NILE VIRUS
Doug
Stearn, DVM
Staff Veterinarian
West
Nile Virus (WNV) is a Flavivirus that can cause
encephalomyelitis (inflammation of the nervous system) or
potentially death in horses and humans.
It was first noted in the
United States
in 1999 on Long Island
, New York
. Since that time
it has spread across the United States
.
While
horses become infected with WNV through the bite of infected
mosquitoes, not all will show clinical signs associated with
the virus once they are bitten.
The clinical signs typically associated with infection
are due to inflammation of the spinal cord and brain and
include: ataxia
or stumbling, weakness, muscle tremors, depression, difficulty
swallowing and potentially death.
The
main host or reservoir for the virus is birds.
A mosquito takes a blood meal from an infected bird and
the virus replicates in the mosquito.
Then the mosquito bites the next animal and transmits
the virus to the new animal.
Horses are dead-end hosts for WNV infection because the
virus never replicates enough in the horse for a mosquito to
become infected off of the horse when it takes a blood meal.
Testing
for WNV in horses is done by sampling the blood and checking
for antibodies to the virus.
Positive results indicate recent exposure to WNV.
A positive antibody titer and clinical signs suggestive
of WNV infection would confirm a positive WNV infected horse.
Mosquito
control and vaccination are key in the control of WNV
infection. Horses
are initially vaccinated twice with the WNV vaccine and then
annually thereafter. Mosquito
control is accomplished by removing any potential sources of
water in which mosquitoes can breed and also by applying
insect repellent at times of the day when mosquitoes are most
active.
Treatment
of horses with WNV includes medical management and supportive
care. If a horse
is suspected of being acutely infected with WNV and is
exhibiting early neurological signs, a good addition to
medical management and supportive care would be Colorado Serum
Company’s West Nile
Virus Antibody. When
the West Nile Virus
Antibody is administered intravenously it provides
immediate WNV antibody in the bloodstream, enhancing the
horses ability to fight and neutralize any virus present in
acute cases. The West
Nile Virus Antibody is extremely safe, easy to use and
could improve the horse’s chance of recovery.
Another
use for Colorado Serum Company’s West
Nile Virus Antibody would be as a preventative for WNV.
For example, if horses in your area are contracting WNV
and your horse is not yet vaccinated, you could give your
horse the West Nile
Virus Antibody and vaccinate at the same time.
The West Nile Virus Antibody would give immediate
protection to WNV while the body mounts an immune response to
the WNV vaccine to provide longer term protection. |
