Officials watch for mosquito threat

Confirmed cases of encephalitis and the potential for the West Nile Virus in Mississippi have health officials at a state of heightened awareness to the threat of mosquito-borne illnesses.

Lanny Pace, director of the State Diagnostic Lab in Jackson, Miss., recently informed College of Veterinary Medicine faculty members at Mississippi State University that state health officials are monitoring closely for West Nile virus as well as LaCrosse, St. Louis and Eastern equine encephalitis. West Nile virus is the only one of those mosquito-borne illnesses that has never been diagnosed in Mississippi.

“Recent reports of West Nile virus in northern Florida and southern Louisiana have heightened our awareness of the threat to Mississippi,” Pace said. “It's just a matter of time before West Nile virus hits Mississippi.”

Jim Watson, state veterinarian for Mississippi, said mosquitoes transmit Eastern equine encephalitis from wild birds to horses and humans. Horse cases are almost always fatal. Symptoms include unsteadiness, erratic behavior and a notable loss of coordination. Seizures cause death usually within 48 to 72 hours of the first symptoms. Owners should report horses with suspicious symptoms to veterinarians as soon as possible. Human cases of EEE are rare but often more serious than the other types of encephalitis.

“Eastern equine encephalitis is not new to Mississippi. A vaccine is available, but a high number of horses go unvaccinated each year,” Watson said.

Brigid Elchos, Mississippi's public health veterinarian, said the Centers for Disease Control supplied most states with additional funds to increase their surveillance for mosquito-borne viruses.

“We are testing blood from people if their physicians suspect encephalitis,” Elchos said. “We also are testing dead birds, especially crows and blue jays, for West Nile virus. Last year, we tested 15 birds, and we've already tested 59 this year due to an increased awareness of the potential problems.”

Elchos said West Nile virus typically is first detected in bird populations. Anyone who finds a dead bird, especially a blue jay or crow, should carefully bag it and call the environmentalist at the local health department.

“People should be cautious to avoid mosquito bites all year round, but especially from April through October and at dawn and dusk. Wear mosquito repellants according to label directions and wear long sleeves and long pants whenever out in mosquito-prone areas and times,” Elchos said.

“Efforts to eliminate mosquito habitats are very important in controlling these viruses,” she said. “Keep grass mowed, and drain standing water around the home where mosquitoes might breed. Keep water for animals as fresh as possible.”

Linda Breazeale writes for MSU Ag Communications.

West Nile vaccine available

KEEPING MOSQUITOES from breeding is the best prevention people can use to minimize the risk of contracting the West Nile virus, which has been confirmed to be in Louisiana. The disease, which causes encephalitis, or swelling of the brain, is spread to animals, including humans, through mosquito bites.

Beginning Sept. 1, veterinarians will be able to obtain a vaccine to prevent the disease in horses, according to Dr. Steve Nicholson, LSU AgCenter veterinarian. This is the first time a vaccine, which was developed by Fort Dodge Laboratories in Fort Dodge, Iowa, will be available.

“This is a big breakthrough,” Nicholson said. “If horses get the disease, there is the chance they may die.”

No cases of horses or humans getting the disease have been reported in Louisiana. However, on Aug. 13, a blue jay in Kenner, La., was found to be infected. The disease is spread through migratory birds, such as blue jays, cardinals and sparrows. Mosquitoes that get blood from these birds can spread it to other animals.

“As far as we know, it can be spread to animals only through mosquito bites,” Nicholson said. “It can't be spread from horse to horse or horse to human.”

Nicholson said the West Nile virus is not as great a threat to horses, with about a 40 percent mortality rate, as the eastern equine encephalitis, which has a 95 percent mortality rate.

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