The USDA is recommending that animal owners take several precautions to protect their animals from the West Nile virus. The following recommendations are based on current knowledge about the virus and the 1999 US outbreak.
Mosquito breeding sites
Remove all potential sources of stagnant water where mosquitoes might breed. Precautionary steps include the following:
- Dispose of any water containers, including discarded tires.
- Drill holes in the bottom of containers that are left outdoors.
- Clean clogged roof gutters annually.
- Turn over plastic wading pools or wheelbarrows when not in use, and do not allow water to stagnate in birdbaths.
- Ventilate ornamental pools or stock them with fish.
- Clean and chlorinate swimming pools that are not in use.
- Thoroughly clean livestock troughs monthly.
Use of insect repellents may be of some value in decreasing exposure of horses to adult mosquitoes. Repellents alone should not be relied on, however, to prevent mosquito exposure.
Housing animals in structures with well-maintained insect screening can reduce exposure to adult mosquitoes. Be sure to eliminate mosquitoes from inside the structure first through the use of mosquito adulticides and fans.
The mosquitoes responsible for the transmission of the West Nile virus to horses and other mammalian species generally feed at dawn, dusk, and during the night. The USDA recommends caution when exposing animals to areas inhabited by mosquitoes during these times.
USDA's actions to protect agriculture
The USDA-APHIS Veterinary Services has developed a diagnostic test for the West Nile virus and is on the lookout for virus activity along the Atlantic seaboard. The program surveillance investigates horses showing clinical signs of encephalitis, when other common causes such as rabies can be ruled out. APHIS' Wildlife Services program carries out wild bird specimen collection, initially focusing on East Coast states from Connecticut to Florida, for West Nile virus testing.