St. Croix County horse tests positive for West Nile virus


The St. Croix County Health Department reports that a horse in St. Croix County tested positive for West Nile virus July 27. The Wisconsin Department of Agriculture, Trade and Consumer Protection reported the positive test result to the Wisconsin Division of Public Health.

WNV is transmitted to humans, horses, birds and other animals during bites from infected mosquitoes. Mosquitoes acquire WNV by feeding on infected birds. The virus is not transmitted person to person or directly between animals or between animals and humans. Presence of a WNV positive horse confirms that there are mosquitoes in the area infected with the WNV that can transmit the virus to people and other animals.

The majority of people — 80 percent — 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. Less than 1 percent of people 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 central nervous system illness that can be fatal.

Because WNV is known to be currently circulating, Wisconsin residents and visitors to the state should be vigilant in taking measures to prevent mosquito bites. It is important that people contact their 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 mosquito-borne diseases is to reduce exposure to mosquitoes and eliminate mosquito breeding sites. When cold weather arrives, the mosquitoes will be eliminated, but until then, people are urged to take measures to protect themselves.

The St. Croix County Health Department recommends the following:

• Limit time spent outside at dawn and dusk, when mosquitoes are most active.

• Apply an Environmental Protection Agency-registered insect repellent to clothing as well as exposed skin since mosquitoes may bite through clothing.

• Make sure window and door screens are in good repair to prevent mosquito entry.

• Properly dispose of items that hold water, such as tin cans, plastic containers, ceramic pots, or discarded tires.

• Clean roof gutters and downspouts for proper drainage.

• Turn over wheelbarrows, wading pools, boats and canoes when not in use.

• Change the water in birdbaths and pet dishes at least every three days.

• Clean and chlorinate swimming pools, outdoor saunas and hot tubs; drain water from pool covers.

• Trim tall grass, weeds and vines since mosquitoes use these areas to rest during hot daylight hours.

• Landscape to prevent water from pooling in low-lying areas.

The Department of Health Services has monitored the spread of WNV since 2001 among wild birds, horses, mosquitoes and people. During 2002, the state documented its first human infections and 52 cases were reported that year. During 2016, 13 cases of WNV were reported among Wisconsin residents. Infections in humans have been reported from June through October; however, most reported becoming ill in August and September.

The Wisconsin Division of Public Health will continue surveillance for WNV until the end of the mosquito season. To report a sick or dead crow, blue jay or raven, please call the Dead Bird Reporting Hotline at 1-800-433-1610.

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