Q2) What is West Nile Virus? Is
there a vaccine and should I use it?
West Nile Virus is a sometimes-fatal virus transmitted to birds,
horses, and humans through infected mosquitos. Most parts of the
continental United States have seen at least some occurrences of West Nile Virus
infection, typically during the summer months when mosquitos are most active.
As of 2004, two vaccines are licensed for use in horses to
reduce the risk of West Nile infection. They are West Nile Innovator from
Fort Dodge Animal Health and Recombitek from Merial. Both vaccines have
met USDA requirements for safety testing. Although the vaccines have not
been proven to completely eliminate the virus, they do significantly reduce the
amount of virus circulating in the blood. Most veterinarians recommend
them - be sure to check with yours if you have any questions.
Adult horses are typically given two doses of vaccine. The
second dose should be 3-6 weeks after the first, and should be given at least
one month before mosquito season. Vaccinated adult horses generally need a
booster shot annually.
Foals typically receive three doses: one at 3-4 months of age,
another one month later, and a final dose 6-8 weeks after the second. They
also receive a booster the following spring.
Whether or not you choose to vaccinate your horses for West Nile
Virus, you should remove potential mosquito breeding grounds. These
include areas of standing water such unused water troughs, old tires, and
containers of accumulated rainwater, as well as piles of decaying organic matter
such as leaves and manure. Add mosquito dunks or fish to continually-used
water troughs and ponds to kill mosquito larva, and set up mosquito traps.
Your local authorities may also set up aerial spraying for mosquito reduction.