First frost will help in West Nile fight

October 28, 2002|by RICHARD BELISLE

Franklin County's first killing frost will do what man has been unable to - drive away the mosquitoes that carry the West Nile virus.

The disease has been responsible for the deaths of six Pennsylvania residents - none from Franklin or Fulton counties - and dozens of horses statewide. The dead horses include two in Franklin County that have died since September, said Nan Hanshaw-Roberts, a veterinarian in the state Department of Agriculture.

The majority of horses - about 30 - died in Lancaster County, the biggest Amish enclave in Pennsylvania.

The first horse in Franklin County died Sept. 9, Hanshaw-Roberts said. The Department of Agriculture does not release the owners' names. The second area horse that fell to the virus died Oct. 3. The 18-year-old gelding was owned by Janet Meredith of Hades Church Road.


Meredith volunteered to be interviewed.

"I want other horse owners to know what I've been through," she said.

"A lot of horses get the virus but don't show the symptoms and don't die," Hanshaw-Roberts said. "It's the same with people."

Symptoms in horses include weakness, paralysis of the back legs, inability to get up, muscle twitches and fever, she said.

Meredith said the virus affected her horse's front legs.

"It can affect them there too, but most people don't know that," she said.

The virus affects the brain and spinal cord," Hanshaw-Roberts said.

She said the incubation period runs from five to 15 days. If the disease is fatal in a horse it has a rapid progression, usually only a couple of days.

Meredith's horse was fine the last day she rode him, then died two days later, she said.

At first the veterinarian thought he had colic from eating grass that greened up following recent rains. The vet took a blood test to check for West Nile as a precaution, Meredith said.

She learned a week later the animal died of West Nile virus, she said.

Meredith had her second horse, a 5-year-old gelding, tested for the disease and said last week that the test results show he should be OK.

She had the horse vaccinated, she said.

The vaccine for West Nile virus is still new, Hanshaw-Roberts said. The U.S. Department of Agriculture is still evaluating it, so some owners don't want their horses to be vaccinated until all test results are in, she said.

She said unfounded rumors about the vaccine abound among horse owners.

"Some say that only vaccinated horses have died, but that's simply not true. They weren't fully or properly vaccinated," she said.

"We can't officially recommend the vaccine," Hanshaw-Roberts said. "It's still conditional, but sales are high across the country."

Meredith said her husband had been finding dead birds around their barn all summer, but they were ignored.

West Nile virus was first discovered in birds in the U.S. in 1999.

"Birds seem to be the early warning signs, like canaries in coal mines," Hanshaw-Roberts said.

Chickens also are a good indicator because even if they get the virus they don't get sick, she said.

"There is much more research to do on this disease because it's so new," she said.

Common house mosquitoes - the kind that transmit West Nile - hibernate in dark places over the winter, said Dan Arbegast, chief of vector management for the Pennsylvania Department of Environmental Protection. His department tracks insects and rodents that transmit disease.

The threat of the virus will end for the winter once the first big frost drives the mosquitoes into hibernation.

"The great secret of mosquito control is the winter," Arbegast said. "Snow is the great natural insecticide."

Mosquitoes lay their eggs in the spring in stagnant or still water, he said.

Residents are urged to dump containers of water, empty bird baths and clean gutters or anything where water can collect.

In 2000 the state Legislature appropriated money so each county could launch programs to control mosquitoes.

"It's made a big difference," Arbegast said. "There are only 49 human cases of West Nile in Pennsylvania. The numbers are tremendously higher in some other states. It's working."

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