MOUNT VERNON — The Knox County Health Department has reported that a seven-year-old Mount Vernon child has been diagnosed with LaCrosse virus, a rare and dangerous illness that is transmitted through the bite from an infected mosquito.

The mosquito in question is the eastern treehole mosquito, an aggressive daytime- biting mosquito commonly found in wooded areas. This particular mosquito is known for laying its eggs in the holes of trees where water collects as well as other water collection sites.

Anyone who lives near or spends time in wooded areas is at increased risk for LaCrosse virus. Many people infected with La Crosse virus have no apparent symptoms. For those who do, symptoms typically begin five to 15 days after a mosquito bite and include non-specific symptoms such as: fever, headache, nausea, vomiting and lethargy.

La Crosse virus can only be diagnosed by a healthcare provider through a blood or cerebrospinal fluid sample collected for laboratory testing.

Severe illness most often occurs among children less than 16 years old and is characterized by: seizures, coma, paralysis and a variety of neurologic complications after recovery. Infection from the LaCrosse virus can lead to encephalitis. Death from infection with La Crosse virus is rare and occurs in less than one percent of cases.

The most effective way to prevent infection from La Crosse virus is to prevent mosquito bites. Mosquitoes bite during the day and night. Whenever residents are in areas prone to mosquitos such as high grass, damp areas or wooded areas, they are encouraged to wear insect repellent, treating their skin, clothing and gear.

It is also important to take steps to control mosquito breeding sites. Common mosquito habitats include: tires, gutters, 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 need just a small amount of water to lay their eggs which hatch in just a day or two. La Crosse virus is endemic in Ohio, and Ohio has reported more human cases than any other state in the United States, averaging about 20 cases per year. It is not known where the Mount Vernon child acquired the virus; the family recently spent time camping outside of Knox County. Health department staff plan to meet with the family and conduct an outdoor assessment near the home to determine if there are potential breeding sites to be treated. Environmental Health Director Nate Overholt, R.S., also said that the staff would be spraying pesticide in the area.

According to the Ohio Department of Health, there are currently 14 cases of LaCrosse in 10 Ohio counties. Multiple cases have been reported in Holmes and Franklin counties. Other counties with LaCrosse cases include: Ashland, Geauga, Lawrence, Wood, Portage, Wayne, Hancock and Trumbull.


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