QUESTION FROM MENTEE AMANDA W. IN KY
As some of you may know, the West Nile Virus has struck three animals in Kentucky this year. Two birds in Metcalfe County and a colt in Fayette County. My horse has already been vaccinated for WN, but the colt that died had been vaccinated twice. Is there anyway I can protect my horse from this horrid virus?

Answer from mentor Gopika Chandra, MD in Chicago, IL.
West Nile encephalitis is an inflammation of the central nervous system caused by infection with West Nile Virus. People and animals are infected from the bite of certain kinds of mosquitoes that are infected with the virus. Mosquitoes pick up the virus when they bite, or take a blood meal, from wild birds that are infected with West Nile Virus (WNV). There is no specific treatment for West Nile encephalitis in horses. Supportive veterinary care is recommended. It is important to diagnose WNV because infection is an indication that mosquitoes carrying the virus are in the area and need to be eliminated. A WNV vaccine for horses is now available. It got recently approved for marketing, on a conditional license, which means that the efficacy of the vaccine will be studied for a year. Vaccination of horses is not a guarantee of protection against infection, and does not offer any protection for other animals or people. According to the experts at Purdue University, it is advisable to vaccinate the horses during summer so it provides protection for the rest of the mosquito season and leads to building up resistance to the virus faster when the horse receives a booster dose during spring when the mosquitoes reappear. The best method of prevention of infection with West Nile Virus for people and animals is to reduce the risk of exposure to the mosquitoes that may carry the virus. Reducing the risk involves eliminating mosquito breeding sites to reduce the number of hatching mosquitoes, and to reduce exposure to adult mosquitoes. Mosquitoes breed in stagnant water, so reduction of breeding sites involves eliminating stagnant water sources. To reduce the number of mosquito breeding sites:
1. Dispose of tin cans, plastic containers, buckets, ceramic pots or other unwanted water-holding containers on your property.
2. Pay special attention to discarded tires. Tires are important mosquito breeding sites.
3. Drill holes in the bottom of recycling containers left outdoors. Containers with drainage holes located only on the sides collect enough water to act as mosquito breeding sites.
4. Clean clogged roof gutters every year. Millions of mosquitoes can breed in roof gutters each season.
5. Turn over plastic wading pools when not in use.
6. Turn over wheelbarrows and don't let water stagnate in birdbaths.
7. Empty and refill outdoor water troughs or buckets every few days.
8. Aerate ornamental pools or stock them with fish. Water gardens can become major mosquito producers if they are allowed to stagnate.
9. Clean and chlorinate swimming pools when not in use. Mosquitoes may even breed in the water that collects on pool covers.
10. Use landscaping to eliminate standing water that collects on your property, especially near manure storage areas. Mosquitoes may breed in any puddle that lasts for more than four days.
Additional steps can be taken to reduce the likelihood of exposure of horses to adult mosquitoes: 1. Avoid turning on lights inside the stable during the evening and overnight hours. Mosquitoes are attracted to yellow incandescent bulbs.
2. If light is needed near the stable, place incandescent bulbs outside the stable to attract mosquitoes away from the horses. Black lights (bug zappers) don't attract mosquitoes well.
3. Reduce the number of birds in and around the stable area. Eliminate roosting areas in the rafters of the stable. Certain species of wild birds are thought to be the main reservoir for the virus. (Although pigeons have been shown to become infected with West Nile Virus, they do not appear to act as reservoirs and therefore don't transmit the virus to mosquitoes).
4. Periodically look around the property for dead birds, such as crows. Any suspicious birds should be reported to your local Department of Health. Use gloves to handle dead birds and place the birds in plastic bags, as directed by the Department of Health.
5. Topical preparations containing mosquito repellents are available for horses. Read the product label before using.
6. Fogging of stable premises can be done in the evening to reduce mosquitoes; read directions carefully before using.

For more information;
1. United States Department of Agriculture (717) 782-3442 http://www.aphis.usda.gov/oa/wnv/index.html
2. Pennsylvania Department of Agriculture (717) 783-6897 http://www.pda.state.pa.us/
3. Department of Health 1-877-PA-HEALTH (1-877-724-3258). http://www.westnile.state.pa.us/

References:
1. Animal Information. www.westnile.state.pa.us/animals/horses.htm
2. Purdue News. www.news.uns.purdue.edu/UNS/html3month/011001.Couetil.westnile.html