Summer 2012 could be a heavy season for mosquito populations; Penn Vet expert advises vaccinations and vigilant management

[April 20, 2012; Kennett Square, PA] – A mild winter has been pleasant for residents of the Mid-Atlantic region. It has also created a favorable environment for mosquitoes. With mosquitoes comes the potential to contract West Nile Virus, a debilitating and potentially deadly disease. The first case of the season of West Nile Virus has been reported in a horse in Northampton County, PA. Entomologists are predicting that weather conditions could make this a particularly heavy mosquito season, and a two-pronged approach of vaccination and management is the most successful way to avoid the disease, according to Ray Sweeney, VMD and Chief of Medicine at New Bolton Center, the large animal campus of Penn Vet.

West Nile Virus, transmitted by mosquitoes and occasionally other blood-sucking insects, causes an inflammation of the brain and spinal cord that can result in a variety of symptoms including fever, lack of coordination, weakness, muscle twitching, colic and intermittent lameness. Approximately one-third of all horses exhibiting signs of the illness do not survive. Although the disease is now considered endemic to all of North America, risk of exposure varies with changes in populations of insect carriers.

Dr. Sweeney advises that the risk of contracting the West Nile Virus can be lessened through both appropriate vaccination and careful management. “Proper vaccination has been very effective in reducing the number of West Nile Virus cases in horses, from an outbreak situation a few years ago to practically no cases reported in horses in Pennsylvania in more recent years,” says Dr. Sweeney. “There is a concern that if we let our guard down and stop vaccinating horses, we will begin to see more cases again.” Vaccination against West Nile Virus is very effective, he adds, but it doesn't last forever. “Horse owners are encouraged to check with their veterinarian to find out whether a booster vaccination is recommended.”

Management practices also play a significant role in reducing exposure to the infected mosquitoes. Horse owners are advised to take the following steps: eliminate all standing water from the property, including puddles hiding in old tires, watering cans, gutters and low-lying areas; arrange turnout schedules so that horses are in the barn at dusk and dawn, prime mosquito feeding times; keep mosquitoes from the barn through the use of fans, traps and horse-friendly repellents; and use approved repellents on horses and any clothing such as fly sheets as well.