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A cerebral spinal fluid sample from an 80-year-old Faribault County man tested positive for West Nile virus antibody at a hospital laboratory at the Minnesota Department of Health's laboratory in Minneapolis.

The sample has been sent to the Centers for Disease Control and Prevention in Atlanta for confirmation.

The Faribault County man was hospitalized in late June with symptoms including fever, severe headache, disorientation, unsteady gait, and fatigue. He has since been released and is recovering. His illness was consistent with aseptic meningitis, a severe form of the West Nile virus infection.

"While this case occurred earlier than the first cases last year, we still expect the peak time for transmission of the virus to humans to be from now through mid-September," said Dr. Harry Hull, state epidemiologist. "The mosquitoes that carry West Nile begin their activity in May, but it takes some time for the disease to build among mosquitoes and birds before it is more likely to spread to the human population."

So far in 2003, West Nile virus has also been found in three horses in the state in three counties (Crow Wing, Sherburne, and Washington) and in six birds from four counties (Dakota, Hennepin, Ramsey, and Washington).

West Nile virus is transmitted through the bite of an infected mosquito. It cannot be spread by contact with an infected person.

While rarely serious in humans, it can lead to encephalitis, an inflammation of the brain.

Hull said that the threat to any one person of becoming ill from West Nile virus is still extremely low. Most mosquitoes do not carry the virus, so most people bitten by a mosquito will not be exposed to the virus.

Of those who become infected, most will have no symptoms at all or display only mild symptoms, according to the Centers for Disease Control. Fewer than one out of 150 people who become infected will get seriously ill.

Symptoms usually show up three to 15 days after being bitten. They can include headache, high fever, muscle weakness, stiff neck, disorientation, tremors, convulsions, paralysis, and coma. Severe cases tend to occur more often in the elderly.

Physicians are urged to be vigilant for patients who have symptoms consistent with West Nile virus.

"The first case reaffirms our advice to all Minnesotans to take steps to protect themselves from mosquito bites," said David Neitzel, an epidemiologist with the Department of Health who specializes in diseases transmitted by mosquitoes and ticks.

To reduce your risk of being bit by a mosquito:

•Use a good repellent, containing no more than 30 percent of DEET while outside among mosquitoes.

•Wear long-sleeve shirts and long pants if you have to spend time in an area where mosquitoes are biting.

•Avoid outdoor activities at dusk or dawn, when mosquitoes feed.

•Eliminate mosquito-breeding sites like tires, buckets, rain gutters, cans, and anything else that can hold water. Change the water in bird baths or horse troughs at least weekly.

West Nile virus is widespread in Africa, the Middle East, and parts of Europe. The virus first appeared in North America in 1999 and has now been found in 44 states plus the District of Columbia.

In 2002, 48 human cases of West Nile virus were reported in Minnesota, with no deaths. Nationwide in 2002, there were 4,156 human cases and 284 deaths.

So far in 2003, five other human cases have been reported in three states: Texas, South Carolina, and Alabama.