Mosquito trap

Mayre Newcomb, an intern with the Knox County Health Department adds liquid to a Gravid Trap as part of the agency’s mosquito surveillance program.

MOUNT VERNON -- Despite the wet weather this summer and an increase in breeding sites for mosquitoes, there has not been a human case of West Nile virus in Ohio this year.

There are still a lot of mosquitoes, just very few that are infected with West Nile virus and those that are infected have not bitten any humans. At least, not yet.

Mosquito prevention has changed in recent years with a concentration on killing infected mosquitoes, instead of attempting to kill all mosquitoes. That approach has affected the pesticide spraying schedule for the Knox County Health Department.

“We are no longer just spraying to spray,” said Environmental Health Director Nate Overholt, RS. “The focus of the spraying is not to keep mosquitoes from biting you. It’s to kill infected mosquitoes before they get a chance to bite you.”

The agency is also providing larvacide to treat areas of standing water. Health department staff have been distributing larvacide dunks to township officials for use in public areas like ditches along roads. Local residents can also pick up the dunks at the health department for use on their property.

For the past few summers, the health department has participated in a surveillance program to collect and identify infected mosquitoes. This summer, over 2,200 mosquitoes from 16 different locations have been collected and submitted for testing. So far, none of the insects have tested positive for West Nile Virus.

Throughout Ohio, only 14 collection pools have tested positive.

“We have had a few calls requesting us to spray for mosquitoes,” Overholt said, “and we’ve had a few calls requesting that if we do spray in their neighborhood, to skip their house or property.”

Also influencing the reduced amount of spraying is the cost.

“At $11,000 for a 55-gallon drum of pesticide, we don’t want to waste it,” said Overholt. “If we get a positive sample, we’ll schedule spraying in that area.”

In the past, samples testing positive for West Nile virus have included specific areas of Fredricktown, Gambier, Howard (Apple Valley) and Mount Vernon.

West Nile virus can cause an infection in humans that can lead to encephalitis.

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Most people who become infected with West Nile Virus do not have any symptoms. About one in five people who become infected develop a fever with other symptoms such as headache, body aches, joint pains, vomiting, diarrhea, or rash. There is no specific treatment for WNV infection, and care is based on symptoms.

Overholt said local residents can help with prevention efforts by using insect repellent when they are outside and getting rid of standing water around their homes. When it comes to standing water, no amount is too small.

“Mosquitoes need just a small amount of water to lay their eggs which hatch in just a day or two.” Overholt said. “That’s why it’s important to get rid of standing water on a regular basis.”

Common mosquito habitats include: tires, buckets, cans, bottles, plastic containers, pet food containers and water dishes, planters and pots, including saucers and catch trays. Bird baths should be drained and refilled every 3-4 days.

Mosquitoes are likely to be biting between dusk and dawn.

“If you must be outdoors when mosquitoes are active, wear repellent with DEET,” Overholt said. “Cover up by wearing shoes, socks, long pants and long-sleeved shirts. Also, wear light colors. They are less attractive to mosquitoes.”