About West Nile
Virus
Transmission of West Nile Virus
Symptoms of West Nile Virus
Prevention of West Nile Virus
Testing and Treating West Nile Virus
in Humans
West
Nile Virus and Birds
West Nile Virus and Dogs and Cats
West Nile Virus and Horses
Map of Progression of West Nile Virus Across
the United States
What You Can do to Eliminate Mosquitoes
West Nile
Virus and Horses
Q. Has West Nile Virus caused
severe illness
or death in horses?
A. Yes, while data suggest that
most horses
infected with West Nile Virus recover,
results of
investigations indicate that West Nile
Virus has
caused deaths in horses in the United
States.
Q. Can I get infected with West
Nile Virus by
caring for an infected horse?
A. West Nile Virus is transmitted
by infectious
mosquitoes. These is no documented
evidence
of person-to-person or animal-to-person
transmission of West Nile Virus. Normal
veterinary infection control precautions
should be followed when caring for a horse
suspected to have this or any viral
infection.
Q. How do the horses become
infected with West Nile Virus?
A. The same way humans become
infected—by the bite of infectious
mosquitoes. The virus is located in the
mosquito's salivary glands. When
mosquitoes bite or "feed" on the horse,
the virus is injected into its blood
system. The virus then multiplies and may
cause illness. The mosquitoes become
infected when they feed on infected birds
or other animals.
Q. How does the virus cause
severe illness or death in horses?
A. Following transmission by an
infected mosquito, West Nile Virus
multiplies in the horse's blood system,
crosses the blood brain barrier, and
infects the brain. The virus interferes
with normal central nervous system
functioning and causes inflammation of the
brain.
Q. Can I get infected with West
Nile Virus by caring for an infected
horse?
A. West Nile virus is transmitted
by infectious mosquitoes. There is no
documented evidence of person-to-person or
animal-to-person transmission of West Nile
Virus. Normal veterinary infection control
precautions should be followed when caring
for a horse suspected to have this or any
viral infection.
Q. Can a horse infected with
West Nile Virus infect horses in
neighboring stalls?
A. No. There is no documented
evidence that West Nile Virus is
transmitted between horses. However,
horses with suspected West Nile Virus
should be isolated from mosquito bites, if
at all possible.
Q. My horse is vaccinated
against Eastern Equine Encephalitis (EEE),
Western Equine Encephalitis (WEE), and
Venezuelan Equine Encephalitis (VEE). Will
these vaccines protect my horse against
West Nile Virus infection?
A. No. EEE, WEE, and VEE belong
to another family of viruses for which
there is no cross-protection.
Q. Can I vaccinated my horse
against West Nile Virus infection?
A. A West Nile Virus vaccine for
horses was recently approved, but its
effectiveness is unknown.
Q. How long will a horse
infected with West Nile Virus be
infectious?
A. We do not know if an infected
horse can be infectious (i.e., cause
mosquitoes feeding on it to become
infected). However, previously published
data suggest that the virus is detectable
in the blood for only a few days.
Q. What is the treatment for a
horse infected with West Nile Virus?
Should it be destroyed?
A. There is no reason to destroy
a horse just because it has been infected
with West Nile Virus. Data suggest that
most horses recover from the infection.
Treatment would be supportive and
consistent with standard veterinary
practices for animals infected with a
viral agent.
Q. Where can I get more
information on horses and West Nile Virus?
A. Visit the USDA website
Animal and Plant Health Inspection Service
(APHIS).
(Information on this
page obtained from the Centers for Disease
Control and Prevention)
For West Nile Virus
information updates call toll free:
877-WNV-BIRD (877-968-273)
WestNile.ca.gov
Centers for Disease Control information on
West Nile Virus
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