On August 1st 2001 the U.S. Department of Agriculture issued a press release announcing a conditional license for a killed West Nile vaccine. A conditional license is given to meet an emergency situation, to a limited market, for a local situation or other special circumstance. It is given to a product that has been shown to be pure and safe and reasonably effective while data is still being gathered to prove its potency and effectiveness. The license for the West Nile vaccine is good for one year, in a limited number of states. At the end of that year it will be reevaluated and either given full license or removed from the market.
So should you vaccinate against the West Nile Virus? It is a highly individualized decision. First you should find out if the vaccine is available in your state. Talk to you veterinarian about the reported cases of West Nile in your area and see if he/she recommends vaccinating. Remember the vaccine is still on trial; its effectiveness is still not certain, although it appears to be safe to administer. Remember also that the majority of infected horses do recover.
If you decide to vaccinate you will need to vaccinate twice at three to six week intervals. There are also concerns if you are planning to transport your horse overseas. The vaccine produces antibodies that may not pass import requirements. These antibodies are not permanent but may delay your ability to import the horse into another country.
The most important and effective precaution we can take against West Nile and other diseases is to control mosquito populations. Be sure to eliminate all standing water around your property. Look for old tires, bottles, water laying in tarps, sheets of plastic and stagnant puddles of water. Check rain gutters to be sure they are not clogged. Water troughs should be cleaned out regularly. Be very careful if you decide to use pesticides, since most of these are very toxic. Eliminating the standing water should be able to control most populations. Mosquitoes can breed in any water that is left stagnant for four days, and can breed in as little as a bottle cap full of water. If you have a pond on your property, keep it fully stocked. Fish and frogs eat a lot of mosquitoes. Bats also have a voracious appetite for mosquitoes.
If you would like to keep up-to-date or would like more information on the West Nile Virus, check out these websites:
