NATIONAL 



Agriculture's Animal and Plant Health Inspection 

 Service. This is a killed vaccine product, and its use 

 is no longer restricted to licensed veterinarians. 



In December 2003, Veterinary Services licensed 

 a live vector recombinant vaccine product for use in 

 horses. This product is also available ever the 

 counter. 



Then in July 2005, full licensure was given for the 

 first WNV DNA vaccine for animals in the United 

 States. The vaccine contains two WNV proteins but 

 does not contain any whole WNV, live or killed. Once 

 the horse's cells begin making proteins from the virus, 

 they trigger a protective immune response. This 

 technology represents a new generation of vaccines, 

 using specific fragments of a pathogen's unique 

 genetic materials material to stimulate a targeted 

 immune response from the host (the horse). 



There is no treatment for WNV once a horse 

 becomes infected. About two out of every three 

 horses that become ill will survive. For horses that 

 survive, a full recovery is likely. Horses vaccinated 

 against eastern equine encephalitis, western equine 

 encephalitis, or Venezuelan equine encephalitis are 

 NOT protected against WNV. 



Reduce Mosquito Breeding Sites 



You can decrease the chance of your animals' 

 being exposed to the virus by limiting their exposure 

 to mosquitoes. The best way to do this is to reduce 

 mosquito breeding sites. 



Mosquitoes can breed in any -j Qpxx^mmm 



more than 4 days. The best way to reuuo^ j?'*141 

 to remove any potential sources of standing water in 

 which breeding can take place. 



Dispose of water-holding containers such as old 

 tires. 



Drill holes in the bottom of containers that are left 

 outside. 



Thoroughly clean watering troughs, bird baths, 

 etc., every few days. 

 Clean clogged roof gutters every year. 

 Turn over wading pools or wheelbarrows when 

 not in use, and do not let water stagnate in bird 

 baths. 



Aerate ornamental pools. 



Clean and chlorinate swimming pools that are not 

 in use and do not let water collect on pool covers. 

 • Use landscaping to eliminate low spots where 

 standing water can collect. 



Screened Housing 



Well-maintained insect screening can be useful to 

 reduce exposure to adult mosquitoes if precautions 

 are taken to first eliminate mosquitoes from inside the 

 structure. Fans may reduce the potential ability of 

 mosquitoes to feed on horses. 



Insect Repellant 



Using insect repellants may help decrease 

 exposure of horses to adult mosquitoes. Because 

 under certain conditions (e.g., perspiration) some 

 products have a limited duration of effectiveness, it is 

 not wise to rely solely on repellants to prevent 

 mosquito exposure. Use repellants according to label 

 instructions. Products containing a synthetic 

 pyrethroid compound (such as permethrin) as the 

 active ingredient serve two purposes: (1 ) they offer 

 superior safety and repellent efficacy and (2) they are 

 contact pesticides that kill mosquitoes. 



Outdoor Exposure 



Mosquito species vary in their feeding habits, 

 making transmission possible at any time of day or 

 night. However, a recent epidemiologic study of WNV 

 suggests that keeping horses in stalls at night may be 

 helpful in reducing their risk of infection. 



Additional Information 



For more information about West Nile virus, see 

 http://www.aphis.usda.gov/vs. For information about 

 human health issues related to West Nile virus, see 

 http://www.cdc.gov. 



Figure 2 — Vaccinate your horses before mosquitoes are 

 likely to bite and infect them. (Photo by Dr. Darien Feary, 

 Colorado State University, and used with permission.) 



The U.S. Department of Agriculture is an equal 

 opportunity provider and employer. 



