West Nile virus is here to stay and proactive steps must be taken to prevent the virus from infecting horses and humans.
That message was delivered to 10 people during an informational meeting about the virus Tuesday night at Central Lakes College. Sponsored by the University of Minnesota Extension Service, the meeting included presentations by Dr. Larissa Miniccuci of the University's College of Veterinary Medicine and Joyce Mueller from the Crow Wing County Health Department.
Crow Wing County had the first reported case of the virus in the nation this year when a 5-year-old mare was diagnosed with the virus April 14. The horse was euthanized, the common end of most animals that get the virus. What was unusual about the case was the timing. The virus most often occurs in mid-July through September, the peak of the mosquito season. The Crow Wing horse was infected when few mosquitoes are present. The only other case of the virus so far this year was reported in North Dakota a few weeks later.
Minnesota had 992 horses in 84 counties and 48 people in 31 counties diagnosed with the disease last year. Thirty-eight percent of the horse infections resulted in death. No people died. Nationwide there were 14,717 horses diagnosed (up from 700 in 2001) and 4,156 people diagnosed resulting in 284 deaths. Illinois led the nation with 800 cases resulting in 64 deaths. Another hard-hit state was Louisiana, where 329 cases led to 25 deaths. North Dakota had 17 cases and two deaths and Wisconsin had 52 cases and three deaths.
"Most people think they have a cold or the flu," Mueller said. "The symptoms are many, but high fever is common in 90 percent of the cases. Once you get it there's nothing you can do. It must run its course."
Though any animal can get the virus, horses and humans are especially susceptible. Why is unknown. Common signs include lack of balance, fever, excitability, depression, overall muscle weakness and contractions.
"It's important to remember that a lot of other diseases can show these same signs," Miniccuci said. "Last year we had a horse we suspected had West Nile virus and it turned out to have rabies instead."
Thirty-five species of mosquitoes are known to carry the virus, which they pick up after biting a bird. Any bird can carry the virus though it's found most often in crows and bluejays. To increase the odds that horses are not infected the animals should be fully vaccinated by the end of May. Most veterinary hospitals have the necessary vaccinations.
It's impossible to not get bitten by a mosquito if you spend any amount of time outdoors in Minnesota, but you can lessen the mosquito population on your land by emptying containers that hold rainwater, such as old tires, pails, etc. Wear long sleeves and long pants at dawn and dusk and use repellents with DEET to prevent bites.
West Nile virus was first discovered in Africa in 1937. It appeared in the United States for the first time in 1999 in New York City and has quickly spread westward. All but four states -- Oregon, Nevada, Arizona and Utah -- have reported cases of the virus.
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