West Nile Virus found in Madison County mosquitoes


Madison County Public Health has discovered mosquitoes testing positive for the West Nile Virus (WNV). The positive sample was collected on July 31 from the northwest side of London in Madison County. Public Health received notification of the positive sample from the Ohio Department of Health on Thursday, Aug. 31.

According to Madison County Public Health Commissioner Chris Cook on Friday, there have been no confirmed human cases of West Nile Virus in Madison County this year.

He also said the discovery of WNV-carrying mosquitoes in Ohio is common. “As of the end of August, 58 counties in Ohio have trapped and submitted mosquitoes for testing. Of those 58 counties, 33 including Madison had at least one mosquito pool test positive for WNV,” Cook reported.

When asked if the positive result came as a surprise to him, Cook said, “No. I always work on the assumption that a mosquito is carrying something. That is why we should always protect ourselves.” The positive result came from the testing of a batch of 39 Madison County mosquitoes.

Ohio Department of Health data shows that there have been a total of 1,299 mosquito pools that have tested positive for WNV this year. “When you look at this kind of data, it is pretty evident that WNV can be found in mosquitoes all across Ohio,” Cook said. “Whether its spring, summer, or fall, when we give advice to the public we operate under the assumption that mosquitoes are carrying any number of encephalitis-causing illnesses that can make people sick. We continue to encourage people to wear insect repellent and take steps to protect themselves and their families.”

West Nile Virus is an arbovirus that was first discovered in the United States in 1999. WNV is most commonly spread by infected mosquitoes that can lead to severe fever, encephalitis (inflammation of the brain) or meningitis (inflammation of the lining of the brain and spinal cord).

The most common mosquito in Ohio, the northern house mosquito, or Culex pipiens, carries WNV. Mosquitoes become infected when they feed on infected birds. Infected mosquitoes can then spread the virus to humans and other animals when they bite.

Mayor Patrick Closser said that his staff will be doing additional mosquito spraying in London this weekend. “I am committed to working with Public Health to help protect the citizens of and visitors to the City of London,” Closser said. “We are going to do some extra spraying to help knock down the adult mosquito population.”

There has only been one confirmed human case of West Nile Virus in Ohio this year. That case occurred in Clermont County. Approximately 80 percent of people who are infected with WNV will not show any symptoms at all, but there is no way to know in advance if you will develop an illness or not. Those who develop symptoms usually do so between three to 14 days after they are bitten by the infected mosquito.

About 20 percent of people experience mild symptoms of WNV. Mild symptoms include fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach, and back. Symptoms can last for a few days to as long as several weeks. About one in 150 people infected with WNV will develop severe illness.

Severe symptoms can include high fever, headache, neck stiffness, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness, and paralysis. These symptoms may last several weeks and the neurological effects may be permanent. There is no specific treatment for WNV infection and care is based on symptoms.

Cook reports that many species of mosquitoes are most active from dusk to dawn. However, some species will bite during the day as well. “We want people to stay active outside especially during nice weather,” Cook says. He encourages everyone to use insect repellents. “Approved repellents are the most effective line of defense against WNV and mosquito bites.” When outdoors, use approved repellents containing DEET, picaridin, IR3535, oil of lemon eucalyptus or para-menthane-diol (PMD). It is also important to follow the directions on the package for reapplication. Repellents that claim to be all-natural or made of essential oils or devices that you wear have not been proven to be effective at all.

Other activities you can do to help reduce your risk of WNV include:

• Remove standing water from items such as birdbaths, pet dishes, old tires, small wading pools, buckets, and toys laying in the yard.

• Use screens on windows and doors and repair holes if you see them.

• Wear long-sleeved shirts and long pants especially in the evening.

• Protect younger children and babies with mosquito netting over baby carriers and strollers.

If you have questions about WNV or mosquito control you can contact Madison County Public Health at 740-852-3065 or at info@madisonpublichealth.org.

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West Nile Virus is most commonly spread by infected mosquitoes. Additional mosquito spraying will be done in London this weekend.
http://www.madison-press.com/wp-content/uploads/sites/37/2017/09/web1_Mosquitopiccol-1.jpgWest Nile Virus is most commonly spread by infected mosquitoes. Additional mosquito spraying will be done in London this weekend. Contributed photo
Additional spraying in London this weekend

Staff report