For Immediate Release - May 11, 2011

State Animal Health Officials Caution Livestock Owners on West Nile and Eastern Equine Encephalitis Virus Risk

BOSTON - May 11, 2011 - With warmer weather and mosquito season approaching, state officials are advising livestock owners to be on guard against mosquito-borne diseases like West Nile virus (WNV) and Eastern Equine Encephalitis virus (EEE). The Massachusetts Department of Agricultural Resources (DAR) recommends owners be aware of the risks linked to these diseases and advises protecting certain species of domestic animals by having them vaccinated.

In addition to horses, WNV and EEE pose serious risks to other species such as pheasants, llamas, and alpacas. Since 2000, 58 Massachusetts horses have been infected with WNV and 28 with EEE. In addition, two emus, two alpacas, one llama, and one cow have also tested positive for EEE in the state since 2001.

"By vaccinating the equine population at the right time in the season, horse owners can avoid grief down the road," said DAR Commissioner Scott J. Soares. "Fortunately, there are effective vaccines available for horses, which are particularly vulnerable to these viruses."

In 2010, five horses were stricken by mosquito-borne diseases, with five confirmed cases reported from the towns of Hudson, Lancaster, Middleborough, Plympton, and Warren. Only one was confirmed for WNV, the others were all positive for EEE.

Animal owners should take preventive actions and consult their veterinarian prior to the height of the mosquito season - July and August. Owners are also urged not to wait until positive cases are reported in their area, since it can take several weeks for an animal to be fully protected by a vaccine.

"Every year there is a potential for animals to get bitten by an infected mosquito and keeping current on vaccinations is one way to keep your animals healthy," said DAR's Director of Animal Health Michael Cahill.

Horses cannot spread either WNV or EEE to other animals or humans. Animals such as emus, however, develop hemorrhagic disease when infected and can spread the virus to humans and other susceptible animals that come into contact with the infected blood. Horses and other equines infected by EEE and WNV develop neurologic symptoms that can lead to death. There is no treatment for either infection, although supportive care can be provided.

In addition to vaccination, owners should reduce potential mosquito breeding sites on their property by eliminating standing water from containers such as buckets, tires, and wading pools - especially after heavy rains. Water troughs provide excellent mosquito breeding habitat and should be flushed out at least once a week during the summer months to reduce mosquitoes near paddock areas. Horse owners should keep horses in indoor stalls at night to reduce their risk of exposure to mosquitoes.

If an animal is diagnosed with WNV or EEE, owners are required to report to DAR, Division of Animal Health by calling 617-626-1795 and to the Department of Public Health (DPH) by calling 617-983-6800

The State Reclamation and Mosquito Control Board within the Massachusetts Department of Agricultural Resources oversee mosquito control in Massachusetts. For more information call 617-626-1777 or visit,

DAR logo DAR's mission is to ensure the long-term viability of local agriculture in Massachusetts. Through its four divisions - Agricultural Development, Animal Health, Crop and Pest Services, and Technical Assistance - the DAR strives to support, regulate and enhance the Commonwealth's agricultural community, working to promote economically and environmentally sound food safety and animal health measures, and fulfill agriculture's role in energy conservation and production. For more information, visit DAR's website at , and/or follow at