What Are The Symptoms of West Nile Virus?

Unless you’ve been — or perhaps even if you have been — living in a cave, you know mosquitoes have been bad this summer.

Very bad.

The heavy, frequent rains in the region in June and July have made northwest Ohio and southeast Michigan a breeding ground for the pesky, blood-sucking insects.

In addition to leaving itchy bumps on our skin, infected mosquitoes can also spread an arthropod-borne virus known as West Nile virus (WNV), which can lead to severe fever, encephalitis (inflammation of the brain) or meningitis (inflammation of the lining of the brain and spinal cord), according to the Ohio Department of Health (ODH). The mosquitoes become infected with the virus when they feed on contaminated birds and then pass the virus to humans, as well as other animals. The virus is not spread person to person.

The first two human cases of WNV this year were reported in late July — one in the Cleveland area and one in the Cincinnati area.

The virus was first detected in the United States in New York City in 1999 and first appeared in Ohio in 2001. According to the ODH, the number of WNV cases in Ohio peaked in 2002 with 441 cases, a number which quickly and drastically lowered in following years (with the exception of 2012, which had 122 cases). Last year, there were 11 cases reported statewide.

Although no humans in northwest Ohio have tested positive for WNV this summer, a mosquito “pool” in Lucas County has recently tested positive for the virus.

Karen Christie, RN, an infection preventionist at ProMedica, says that although the most severe symptoms of WNV can create life-threatening situations, a vast majority (80 percent) of those infected will show no symptoms at all. Only one in 150 will develop a serious illness.

Up to 20 percent of people infected will display rather minor illnesses, such as fever, headache, body aches, and vomiting. The more rare, severe problems include high fever, neck stiffness, disorientation, coma, convulsions, tremors, vision loss, muscle weakness, numbness, and paralysis. Individuals over the age of 50 are at increased risk of severe illness, she says.

“These can last for several weeks, and some of them may be permanent,” Christie says. “With viruses, and this one in particular, it really is treating the symptoms. If they’re critically ill, certainly trying to maintain all their bodily systems is very important, but it’s really symptomatic, supportive treatment.”

Until symptoms arrive later, “you aren’t going to know if you’ve been bitten by an infected mosquito or not,” Christie warns. Those developing symptoms usually do so between 3-14 days after being bitten.

The wet conditions this summer have greatly increased mosquito breeding grounds: Standing water. An infected mosquito can transmit the virus to their eggs, according to the ODH.

Any stagnant, standing water should be removed from containers, Christie says, noting that places such as rubber tire swings, saucers under flower pots, pet bowls and bird baths could be adequate breeding locations.

“If you have any of those around your house, empty them out,” she says.

How can you reduce the chances you or a loved one will become infected with WNV?

“The main times mosquitoes are more active are early morning and in the evening,” Christie says. “Stay indoors at those times. If you are outdoors, there’s a recommendation to wear long sleeves and pants so your skin is covered as much as possible and to use insect repellent.”

ODH recommends using repellents containing DEET, picaridin IR3535, oil of lemon eucalyptus or para-menthane-diol.

Click here to learn more about protecting you and your loved ones against mosquito-borne illnesses.