Those pesky mosquitoes – sometimes it seems they can make the joys of Minnesota summers turn to nothing more than itchy, annoying red bumps. But that isn’t all. Mosquitoes can also transmit diseases, one of which is the West Nile virus.

As its name would suggest, the West Nile virus was discovered in the West Nile district of Uganda back in 1937. It wasn’t until 62 years later – in 1999 – that the first outbreak of the disease occurred in the United States (in New York City.) During that time, there were outbreaks in Europe, Asia, the Middle East, Russia and Australia.

While it’s received a lot of media attention, in most cases the West Nile virus is not serious. In fact, most people with the disease experience no symptoms or symptoms so mild that they do not realize they have been infected.

About 20 percent of people who are infected with the virus develop a mild condition called West Nile fever. Symptoms of West Nile fever develop three days to two weeks after infection and can include: fever, headache, muscle ache, back ache, lack of appetite, nausea, vomiting, diarrhea, skin rash, and swollen lymph nodes. Symptoms of West Nile fever usually last just a few days.

Less than one percent of people who contract West Nile virus develop a more serious infection, which affects the brain or spinal cord, causing encephalitis, meningitis, or paralysis. Signs and symptoms of these conditions include: high fever, severe headache, stiff neck, disorientation, confusion, stupor, tremors, in coordination, convulsions, partial paralysis, and coma. Symptoms of encephalitis or meningitis may last several weeks, and certain neurological effects may be permanent.

The risk of developing a serious infection from West Nile virus increases with age. The risk is greatest for people over 50 or those with a weakened immune system.

While all this sounds a bit scary, it’s important to remember that most of the time, West Nile virus is not serious, and that contracting it is quite rare. Even so, in 2003, the Centers for Disease Control and Prevention (CDC) reported more than 9,800 human infections in the United States with over 250 deaths from the disease.

While the West Nile virus is spread to humans by mosquitoes, it is actually housed in birds. Birds act as a reservoir for the virus – meaning the virus multiplies in them. When certain species of mosquitoes bite infected birds, the mosquitoes become infected and may spread the virus to humans and animals such as horses and dogs.

The virus cannot be spread from these animals to other animals or to humans. People with the virus care not contagious.

There is currently no vaccine or antidote for the West Nile virus. Treatment for the virus involves supportive care in a hospital to help the body fight the illness. Supportive care can include intravenous fluids, respiratory support, and prevention of secondary infections such as pneumonia.

The best defense against West Nile virus is probably prevention. This means decreasing your risk for mosquito bites. Wear long sleeves and pants when outdoors. Use insect repellent. Be aware of peak mosquito hours – early morning and early evening – and avoid outdoor activities during these times. Mosquitoes lay their eggs in standing water, so drain any of it that is near your home.

If you experience signs or symptoms that indicate West Nile infection, see your doctor as soon as possible. This is especially important if you are pregnant, breast-feeding, elderly, or in poor health. Your doctor can confirm the presence of the virus in your body by drawing a sample of your blood.

West Nile virus is rare and usually not serious. In areas where the disease is spread, less than one percent of mosquitoes are infected. Of people bitten by an infected mosquito, fewer than one percent will become severely ill. It’s in your best interest to avoid mosquito bites by using the prevention measures listed above. With a few extra precautions, you can enjoy our Minnesota summer – mosquitoes and all.

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Dr. Ripp is a board certified family practice physician at Raiter Clinic in Cloquet.