WINNIPEG – Farm families and horse owners across Western Canada may
soon have to face West Nile virus but there’s little they can do to
fully protect themselves from it.
However, veterinary and human health experts say the disease presents a
low risk to humans.
“It’s prudent to avoid mosquito bites, but the risk is extremely low,”
said Dr. Susan Roberecki, Manitoba’s deputy chief medical officer.
Dead crows infected with West Nile virus have been found in the Red
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River Valley. The first was found in Winnipeg. The second was found in
the nearby Rural Municipality of St. Andrews.
In North Dakota, a dead horse was found to be infected with West Nile
virus, which has been spreading across North America from the East
Coast, where it was first discovered in 1999.
The disease is an encephalitis, which means it causes brain swelling.
That causes loss of co-ordination and it can kill in severe cases. It
is similar to western equine encephalitis.
West Nile virus is spread by mosquitoes. It generally spreads from
birds in the crow family.
Gopi Nayar, a Manitoba Agriculture veterinary microbiologist, said
cattle, pigs, sheep, goats and poultry will not be sickened by the
disease, but horses can develop it.
Humans can be protected by lowering the number of mosquitoes near homes
and workplaces and by mosquito-proofing houses, Roberecki said.
Winnipeg neighbourhoods are being fogged with malathion gas, but that
isn’t an option for most farmers. However, city and rural residents are
being urged to eliminate standing water around homes where mosquitoes
hatch.
Roberecki said the mosquito breed that most actively spreads the
disease likes to breed in old tires and other containers, so those
should be removed from around homes.
Mosquito repellent can also reduce bites.
Jonathan Naylor of the Western College of Veterinary Medicine in
Saskatoon said horses can be protected by stabling them at dusk and
dawn (when mosquitoes are most active), treating them with mosquito
repellents, and having them graze away from swampy areas.
Naylor said a West Nile virus vaccine for horses is available. Horse
owners in Canada can contact a veterinarian, who can bring in the
vaccine in a week to 10 days.
But Naylor said the vaccine’s effectiveness is not known, and some
reports suggest it does not offer full protection. He suggests horse
owners concentrate on mosquito bite reduction rather than relying on a
vaccine.
