Horse in Clark County Tests Positive for West Nile Virus

Monday, August 21st, 2023 -- 2:00 PM

The Clark County Health Department (CCHD) was notified on August 18 that a horse in Clark County tested positive for West Nile Virus (WNV) on August 8, 2023.

The CCHD is therefore reminding people to protect themselves from mosquito bites. The presence of a horse with WNV confirms that mosquitoes in the area infected with WNV can transmit the virus to people and other animals.

WNV is transmitted to humans, horses, birds, and other animals through the bite of an infected mosquito. Mosquitoes acquire WNV by feeding on infected birds. The virus is not spread from person to person, animal to animal, or animal to person.

Most people (80%) who are infected with WNV do not get sick. Those who do become ill usually experience mild symptoms such as fever, headache, muscle ache, rash, and fatigue. However, some people (less than 1%) who become infected with the virus get seriously ill with symptoms that include high fever, muscle weakness, stiff neck, disorientation, mental confusion, tremors, confusion, paralysis, and coma.

Older adults and those with compromised immune systems are at greater risk of developing severe illness that can be fatal. It is important that people contact a health care provider if they suspect they have WNV illness.

Horse owners should be reminded to contact their veterinarian to vaccinate their animals. In addition to vaccination, horse owners can protect their horses by removing standing water and keeping animals inside from dusk to dawn.

The best way to avoid illnesses spread by mosquitoes is to reduce exposure to mosquitoes and eliminate mosquito breeding sites. Mosquitoes will no longer be active once there is a hard frost (temperatures below 28 degrees for at least four consecutive hours), but until then, people are urged to take measures to protect themselves.

The CCHD recommends to avoid mosquito bites by:

• Applying an insect repellent with DEET, picaridin, oil of lemon eucalyptus, or IR3535 to exposed skin and clothing;
• Prior to heading outdoors, treat clothing with permethrin and do not apply permethrin directly to skin;
• Consider rescheduling outdoor activities that occur during evening or early morning hours, when mosquitoes are most active;
• Wear long sleeves, long pants, and socks when outdoors to help keep mosquitoes away from your skin.

Also, mosquito-proof your home by:

• Making sure window and door screens are intact and tightly fitted to prevent mosquitoes from getting into your home;
• Prevent mosquitoes from breeding around your home by removing stagnant water from items around your property, such as tin cans, plastic containers, flower pots, discarded tires, roof gutters, and downspouts;
• Turn over wheelbarrows, kiddie pools, buckets, and small boats such as canoes and kayaks when not in use;
• Change the water in bird baths and pet dishes at least every three days;
• Clean and chlorinate swimming pools, outdoor saunas, and hot tubs;
• Drain water from pool covers;
• Trim or mow tall grass, weeds, and vines since mosquitoes use these areas to rest during hot daylight hours.

The WI Department of Health Services (DHS) has monitored the spread of West Nile virus since 2001. An average of 11 human cases of WNV were reported among Wisconsin residents each year during 2018–2022.

WNV infections in humans have been reported from June through October; however, most people with WNV reported becoming ill in August and September.

Feel free to contact us with questions and/or comments.