With the first human cases of West Nile virus disease for 2008 confirmed in three Minnesota residents, state health officials are urging Minnesotans to protect themselves from mosquitoes from now through September.

According to Freeborn County Public Health Director Lois Ahern, there haven’t been any symptoms of the virus in southeast Minnesota or Freeborn County as of July 28.

There were a few cases found nearby Freeborn County in 2007. There weren’t any human cases found in Freeborn County but a case was found in a horse. Despite Freeborn County records, there were human cases found in Mower and Faribault counties.

“Culex tarsalis, the primary mosquito carrier of West Nile virus in Minnesota, was at low levels earlier this summer when weather was cooler than normal, but its numbers have begun to rise with recent warm weather,” said David Neitzel, an Minnesota Department of Health epidemiologist specializing in diseases carried by mosquitoes and ticks. “Rising numbers of this mosquito species, the first human cases, and recent findings from mosquito and bird monitoring mean that the peak West Nile virus risk season has begun.”

Culex tarsalis mosquitoes are well established in Minnesota and there is always a possibility to come in contact with a mosquito carrying the virus. Not all mosquitoes carry the virus, only the species of Culex tarsalis does.

Illness from West Nile virus can occur in residents throughout Minnesota and among all age groups. However, West Nile virus risk is greatest in western and central counties, where Culex tarsalis mosquitoes are most common. Those who are elderly or have weakened immune systems are more susceptible to developing a severe illness from West Nile virus infection.

The first three Minnesota cases of this year were residents of Becker, Carver and Clay counties. The Clay County resident is a man in his 60s and the Becker and Carver county individuals were both under the age of 20. They all experienced onset symptoms in early to mid-July and were later diagnosed with West Nile fever, a milder form of West Nile virus-related illness. All three people are now recovering.

To limit further cases of the West Nile virus, Minnesota Department of Health officials strongly urge people to use one of the many mosquito repellent options now available and take other simple precautions.

“We expect the risk of West Nile virus-related illness to increase during late July and August as more Culex tarsalis mosquitoes are feeding,” Neitzel said. “This puts Minnesotans at risk for severe or even fatal illness, but people can reduce their chance of West Nile virus infection by using mosquito repellents at dusk and dawn.”

According to the Minnesota Department of Health, here are some safe and effective options to use to defend yourself against mosquito bites and West Nile virus:

– Repellents containing Deet (up to 30 percent concentration) are still the most widely used and can provide long-lasting protection against mosquito bites.

For people who prefer not to use Deet, effective alternatives include repellents containing picaridin, oil of lemon eucalyptus or IR3535.

– Repellents containing permethrin are recommended for use on clothing (not skin). Permethrin is a strong repellent and will kill mosquitoes that come in contact with treated clothing.

– For maximum effectiveness and safety, all mosquito repellents should be used according to label directions.

“The key to avoiding West Nile virus illness is to keep repellent on hand from July through September, and to use it diligently,” Neitzel said.

Other important steps to prevent mosquito bites and serious illness from West Nile virus, according to the Minnesota Department of Health, include:

– Minimize outdoor activities at dusk and dawn, as this is prime feeding time for West Nile virus-carrying mosquitoes. If you go outside at these times, take precautions even if mosquito numbers seem low. It only takes one bite from an infected mosquito to transmit the virus.

– Wear loose-fitting, light-colored, long-sleeve shirts and long pants if you must spend time in an area where mosquitoes are biting.

Of those who become infected with West Nile virus, most people will fight off the virus without any symptoms or will develop West Nile fever, the less severe form of the disease. Approximately 1 out of 150 people bitten by infected mosquitoes will develop severe central nervous system disease (encephalitis or meningitis). Approximately 10 percent of people with this severe form of West Nile virus infection die from their illnesses, and many more suffer from long-term nervous system problems.

Symptoms usually show up 3 to 15 days after being bitten. They can include headache, high fever, rash, muscle weakness, stiff neck, disorientation, convulsions, paralysis and coma. Severe cases tend to occur most often in the elderly and people with immune system problems.

Information on West Nile virus can be found at the MDH Web site: www.health.state.mn.us. Further information on repellents is at the CDC Web site: www.cdc.gov/ncidod/dvbid/westnile/RepellentUpdates.htm.

People who have questions about West Nile virus can call MDH at (651) 201-5414 or (877) 676-5414 between 8 a.m. and 4:30 p.m. Monday through Friday.