MOUNT VERNON —The Knox County Health Department has been notified by the Ohio Department of Health that an Eastern Knox County horse tested positive for West Nile virus. The horse was euthanized by its owner after it did not respond to treatment.
“Horses contract West Nile virus in the same manner as humans: By the bite of an infected mosquito,” said Scott Harmon, DVM and a member of the Knox County Board of Health. “Mosquitoes become infected when they feed on infected birds. Infected mosquitoes can then spread West Nile virus to humans and other animals when they bite.”
However, unlike humans, horses can be protected from WNV by a vaccine that is readily available from veterinarians. “Even if a horse has been vaccinated for the different strains of encephalitis, most commonly Eastern and Western Encephalitis, which are also transmitted by mosquitoes, horses should still be vaccinated for West Nile virus,” said Harmon.
“An infected horse that has not been vaccinated can recover, but there is no direct treatment for the disease,” said Harmon. “Treatment involves supportive care which can become a financial and physical burden. Successful treatment is not guaranteed.”
Nate Overholt, RS, director of environmental health for the health department, talked with the veterinarian who treated the infected horse. “The horse initially responded to treatment. It was able to get up and stand for several hours after treatment,” said Overholt. “Then the horse laid down and would not get up. A second treatment was administered and the horse still could not stand. At that time, the owner decided to have it euthanized.’
Harmon said there is no documented evidence that WNV is transmitted directly between horses or to humans. However, horses with suspected West Nile virus should be isolated so that they do not become a reservoir for infecting more mosquitoes.
WNV has been detected in birds and mosquitos in Knox County for the past 11 years. There have been a few human cases, but the individuals recovered.
“In the past, we asked residents to bring in dead birds for testing,” said Overholt. “But that’s not necessary anymore. We know the virus is here and it can be harmful to humans. One bite from an infected mosquito can lead to a severe and possibly life-altering illness”
To help with the elimination of mosquitoes, the health department applies an EPA-approved pesticide in areas that are prone to mosquito infestation, especially where there will be large gatherings of people, such as at recreation parks and during community festivals. “Unfortunately, we have not been able to spray recently as much as we would like due to wet weather and cooler evenings,” said Overholt.
Healthy, active adults who are 50 and older have the highest risk of illness caused by West Nile virus. People who work outdoors in occupations like farming or construction are at greater risk of getting bitten by an infected mosquito. “Prevention is the key to protection,” said Overholt.
People can stay healthy by using simple, proven strategies to protect themselves and their families. In particular, consumers are advised to use mosquito repellent products containing EPA-approved active ingredients, such as DEET, picardin, or oil of lemon eucalyptus.
Around the house, Overholt stressed the importance of eliminating standing water. Some common mosquito habitats include: Tires, buckets, cans, bottles plastic containers, pet food containers and water dishes, planters and pots, including saucers and catch trays. Bird baths should be drained and refilled every 3-4 days.
Other easily overlooked areas include vinyl covers for pools, grills and lawn furniture that collect water; clogged gutters and downspouts, leaky outside faucets that create puddles and mature trees that have developed cavities or holes that hold water — fill these voids with sand. “Basically, anything that has the potential to hold even small amounts of water can be a breeding site for mosquitoes. Up to 30 larvae can incubate in a single pop bottle cap of water,” said Overholt.
“If people find dead birds, especially crows or blue jays, we would like to hear about it. It helps us track West Nile activity in the county. But there is currently no testing.” said Overholt.
Seasonal activity for mosquitoes varies from year to year, but mosquitoes carrying diseases including WNV, St. Louis encephalitis and LaCrosse encephalitis remain a threat. Ohio led the nation in cases of LaCrosse encephalitis with 51 cases in 2011. WNV has spread from coast to coast with new cases being reported daily. WNV activity in the United States often does not peak until late September. WNV can cause serious neurological illnesses, such as meningitis and encephalitis. Last year, WNV was responsible for more than 1,000 illnesses and nearly 100 deaths nationwide. In Ohio, from 2006-2010, 15 human cases were reported. Yet, many cases are not reported, so the true number of WNV-related illnesses is likely to be higher.