Equine Mosquito-borne Diseases at High Level

Horse owners are urged to vaccinate to prevent diseases like West Nile virus (WNV) and Eastern Equine Encephalomyelitis (EEE).

September 5, 2012–With more than 75 confirmed cases of equine West Nile virus1 (WNV) and 79 confirmed cases of Eastern Equine Encephalomyelitis2 (EEE) around the country as of the middle of August, 2012 could be a record year for horses contracting mosquito-borne diseases. The Centers for Disease Control and Prevention has already confirmed that 2012 has the highest number of human West Nile virus cases since 2004,3 and a spokesperson says,”It is not clear why we are seeing more activity than in recent years.”

Besides the equine cases and human cases, WNV has been reported in more than 10,000 mosquito pools4 and in hundreds of birds.5 In the case of EEE, at least two human cases have been reported,6 and the disease has been detected in more than 100 mosquito pools in three states.7 With warm weather still in the forecast for the coming months, the chances of additional cases being reported are high.

What does this mean for horse owners?

A threat to horses, both WNV and EEE are mosquito-borne – meaning a horse could be just one bite away from becoming infected. “It’s important for horse owners to look at the whole picture when they are discussing vaccination protocols with their veterinarians,” says April Knudson, DVM, equine specialist, Merial’s Large Animal Veterinary Services. “There are literally tens of thousands of mosquitoes carrying these diseases, and an unvaccinated horse is an unprotected horse.”

The effects of both WNV and EEE are devastating. In the case of WNV:

One out of three horses that gets sick from WNV dies or must be euthanized.8

The expense of treating a horse for WNV, which can be 45 times that of the vaccine,9 may prove cost-prohibitive for some horse owners.

40 percent of horses that survive the acute illness caused by WNV still exhibit gait and behavioral abnormalities six months after diagnosis.8

In the case of EEE, infected horses have a 90 percent mortality rate.10

How can horse owners provide protection?

Vaccinate with a Proven, Safe, Effective Product

“Vaccinating against WNV, EEE and other equine diseases is the most important thing horse owners can do to protect their horses,” says Dr. Knudson. “Even though the season is already upon us, it isn’t too late. The vaccines available are highly effective, fast-acting and affordable, especially when compared with the cost of care once the horse is suffering from the disease.”

Merial’s fast-acting11 RECOMBITEK? rWNV-EWT combination vaccine offers protection against not only EEE and WNV, but also WEE and tetanus. Following initial vaccination, horses need to be revaccinated annually to help safeguard against disease.12

Stay Informed with Outbreak Alert
An additional tool horse owners have at their fingertips is Merial’s free Outbreak Alert program. The program tracks reported cases of WNV, EEE, WEE, Equine Herpsevirus, rabies, equine influenza and Potomac horse fever as they are confirmed around the country. Those who have signed up for the service receive texts and/or e-mail messages notifying them of confirmed disease threats in their areas. Owners who travel with their horses can enter multiple ZIP codes in the site’s search field to help them stay abreast of disease threats throughout the country. There are also veterinarian-exclusive features available, including printable materials veterinarians can share with their clients.

“The Outbreak Alert website features maps showing instances of diseases horse owners should be concerned about,” says Dr. Knudson. “When they are able to see all the locations of confirmed reports in horses and other species, it helps bring home how much of a threat these diseases can present.”

To sign up for the program or learn more about equine diseases, visit outbreak-alert.com.

Manage the Environment
While the best way to defend against equine diseases like WNV and EEE is to vaccinate, horse owners can help minimize the mosquito population in their immediate surroundings by following these practices:

Eliminate standing water.13

Empty or change the water in bird baths, fountains and plant trays regularly.13

Drain or fill temporary pools of water with dirt.13

Keep lights off in the barn, or switch to yellow “bug” lights which tend to attract fewer mosquitoes.13

Use mosquito-repellent spraying systems in the barn.

To learn more about WNV, EEE, other equine diseases and vaccination guidelines, or to sign up for Outbreak Alert, visit outbreak-alert.com.

About Recombitek rWNV-EWT
Recombitek rWNV-EWT vaccine is a combination vaccine labeled to aid in the prevention of disease and viremia due to West Nile virus and encephalitis caused by Eastern Equine Encephalomyelitis Virus (EEEV) and Western Equine Encephalomyelitis Virus (WEEV) and tetanus caused by the Clostridium tetani toxin.12

?RECOMBITEK is a registered trademark of Merial Limited. ?2012 Merial Limited, Duluth, GA. All rights reserved. EQUIBGN1234 (08/12)

1Disease maps page. United States Geological Survey Web site. Available at: http://diseasemaps.usgs.gov/wnv_us_veterinary.html. Accessed August 15, 2012.
2Disease maps page. United States Geological Survey Web site. Available at: http://diseasemaps.usgs.gov/eee_us_veterinary.html. Accessed August 7, 2012.
3 Centers for Disease Control and Prevention. Press release. West Nile virus disease cases up this year. Available at: http://www.cdc.gov/media. Accessed August 7, 2012.
4Disease maps page. United States Geological Survey Web site. Available at http://diseasemaps.usgs.gov/wnv_us/mosquito.html. Accessed August 15, 2012.
5Disease maps page. United States Geological Survey Web site. Available at: http://diseasemaps.usgs.gov/wnv_us_bird.html. Accessed August 15, 2012.
6Disease maps page. United States Geological Survey Web site. Available at: http://diseasemaps.usgs.gov/eee/us_human.html. Accessed August 15, 2012.
7Disease maps page. United States Geological Survey Web site. Available at: http://diseasemaps.usgs.gov/eee_us_mosquito.html. Accessed August 15, 2012.
8Guidelines for the vaccination of horses: West Nile virus. American Association of Equine Practitioners. Available at: http://www.aaep.org/wnv.htm. Accessed August 7, 2012.
9Gardner I, et al. Incidence and effects of West Nile virus infection in vaccinated and unvaccinated horses in California. Vet Res. 2007;38(1):109-116.
10Eastern/Western equine encephalomyelitis. American Association of Equine Practitioners. Available at: http://www.aaep.org/eee_wee.htm. Accessed August 7, 2012.
11Minke JM, et al. Recombinant canarypoxvirus vaccine carrying the prM/E genes of West Nile virus protects horses against a West Nile virus-mosquito challenge. Arch Virol. 2004(Suppl.);18:221-230.
12RECOMBITEK rWNV-EWT product label.
13United States Environmental Protection Agency. Methods of mosquito control. Available at: http://www.epa.gov/pesticides/health/mosquitoes/mosquito.htm. Accessed August 7, 2012.