Health officials preparing for mosquito-borne virus

MINNEAPOLIS (AP) -- While not expected this year, Minnesota health officials are preparing for the likely arrival of the potentially deadly, mosquito-borne West Nile virus.

Named for its African origin, the West Nile virus doesn't cause serious illness in most healthy people, but it can cause a type of brain inflammation, in about 3 to 15 percent of cases, usually in people with weakened immune systems.

The virus first appeared in the Western Hemisphere in New York in 1999, when seven of the 62 people who contracted the virus died. Since then, West Nile has spread to 12 other states and as far west as Ohio's eastern border.

"Given how rapidly it's spread in other areas, we have every reason to be concerned about this," said Dr. Phil Peterson, an infectious-disease specialist at Hennepin County Medical Center.

"It's not something Minnesotans should be in a panic about, but they do need to be aware of it," he said.

Minnesota is considered a likely West Nile destination because of its high number of mosquitoes and birds that migrate to and from areas where the virus is suspected.

"We suspect that WNV will be introduced into Minnesota at some point in the future," said David Neitzel, an epidemiologist with the Minnesota Department of Health, which is leading the state's preparations for West Nile.

Adding to Minnesota's risk is its extensive interstate transportation system and tire-recycling facilities, Neitzel added. Old tires filled with stagnant water are perfect breeding pools for mosquitoes, and tires hauled into the state to recycling facilities could introduce infected mosquitoes to the area.

"Literally, infected mosquitoes could be just a truckload away," Neitzel said.

The U.S. Geological Survey has issued alerts to its field officers in Minnesota and elsewhere to look for bird die-offs, particularly crows or bluejays, which the virus can kill quickly.

Field officers of the Minnesota Department of Natural Resources have been asked to call in with sightings, DNR spokesman Dennis Stauffer said.

Neitzel also requested in the Minnesota Ornithologists' Union newsletter this spring that members watch for the bird die-offs and to report to the Health Department with the locations of "dead or freshly dead" birds, so the birds can be considered for testing.

The Health Department and the mosquito control agency together are monitoring Culex mosquitoes and periodically send in samples for testing. The agency is using a special trap recommended by the CDC to catch mosquitoes likeliest to carry the virus.

State veterinarian Tom Hagerty said the Minnesota Board of Animal Health also is on the alert, particularly since West Nile has been detected in horses on the East Coast. Veterinarians who suspect West Nile in an animal should call the board, Hagerty said.

Symptoms of severe West Nile infection include headache, high fever, neck stiffness, disorientation, tremors, convulsions, muscle weakness and paralysis.

Kirk Johnson, a vector ecologist with the Metropolitan Mosquito Control District, said Minnesota also has its experience of fighting mosquitoes as a benefit.

"We're in a much better position to handle the introduction of the virus than New York City was," Johnson said.