The Washburn County Health Department reports that a horse in Washburn County has tested positive for Eastern equine encephalitis (EEE) which is caused by the EEE virus. The EEE virus is transmitted by mosquitoes. The Wisconsin Department of Agriculture, Trade and Consumer Protection reported the positive test result to the Wisconsin Division of Public Health. No EEE cases in humans have been reported in Wisconsin this year. Only three human cases of EEE have been reported in Wisconsin between 1964 and 2017.

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

Most people infected with EEE virus do not have symptoms. However, some infected people develop encephalitis (inflammation of the brain) that typically begins with sudden onset of fever, headache, chills, and vomiting. The illness may become severe resulting in disorientation, seizures, coma, or death. There is no specific treatment for this EEE illness.

Clinical signs of EEE infection in horses include depression, loss of appetite, drooping eyelids and lower lip, blindness, paralysis, and death. Horse owners can vaccinate their horses against EEE virus to protect them from becoming ill.

Because EEE virus 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 EEE illness.

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 Washburn County Health Department recommends the following:

  • Limit time spent outside at dawn and dusk, when mosquitoes are most active.
  • Apply insect repellant to clothing as well as exposed skin since mosquitoes may bite through clothing.

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