Public Health Alerts

Eastern Equine Encephalitis

Equine encephalitis strikes in Northern Wisconsin
Release Date: August 31, 2016
Media Contacts:  Raechelle Belli, 608-224-5005   Bill Cosh, Communications Director, 608-224-5020
MADISON – A 2-month old unvaccinated filly from Forest County is the first reported Wisconsin horse to have become infected with Eastern Equine Encephalitis (EEE) this year.  The filly was euthanized on August 23.

“Northern Wisconsin has good mosquito habitat. It’s also been a very wet summer up north, which contributes to the problem,” says Dr. Julie McGwin, equine program veterinarian for the Wisconsin Department of Agriculture, Trade and Consumer Protection.

EEE is caused by a virus transmitted by mosquitoes, and may cause encephalitis, or inflammation of the brain, and is fatal to horses in 90 percent of cases.  Symptoms in horses include depression, appetite loss, drooping eyelids and lower lip, fever, weakness, twitching, paralysis or lack of coordination, aimless wandering, circling and blindness.

The virus is not contagious between horses, but can be carried by mosquitos from an avian, or bird, host to horses and humans. While humans may also be infected by EEE, the virus does not pass directly between people and horses.  Mosquitoes biting warm-blooded animals is the only route of transmission.

Horses that have not already been vaccinated this year for EEE or other mosquito-borne diseases are at greater risk.

“Those horse owners who have vaccinated should check with their veterinarians to see whether a booster is appropriate,” McGwin said.  Horses that have never been vaccinated will need two doses two to four weeks apart, and the vaccine will take at least two weeks to build up enough antibodies to protect them. Vaccines will not protect horses that have already been infected when they receive the injections. Vaccines are available that protect against other strains of equine encephalitis along with EEE, and a separate West Nile virus vaccine is also available.
Besides vaccination, McGwin recommends taking other steps to limit horses’ exposure to mosquitoes during warm weather: 

  • Remove items from surrounding property that could collect stagnant water such as old tires, tin cans, plastic containers. 
  • Keep rain gutters clean and draining properly. 
  • Clean and chlorinate swimming pools, outdoor saunas and hot tubs, and drain water from pool covers. 
  • Turn wading pools and wheelbarrows upside down when not in use. 
  • Empty and replace water in birdbaths at least once a week. 
  • Consider keeping horses in the barn from dusk to dawn, when mosquitoes are most active. 
  • Discuss using equine mosquito repellents with your veterinarian.

Wisconsin last experienced a major outbreak of EEE in 2011, with more than 30 cases mostly in north central Wisconsin.  Since then, sporadic cases have occurred.  Because EEE follows mosquito populations, it normally occurs beginning in mid- to late summer and remains a threat until the first killing frost.

For more information on EEE visit: 


Zika Virus

Zika virus infection is a mosquito-borne arboviral disease transmitted to humans by the bite of infected Aedes aegypti and A. albopictus mosquitoes. The virus can also be spread through all types of sexual contact, and from a pregnant mother to her fetus.

Women who are pregnant or trying to become pregnant are advised to avoid travel to high-risk areas. If they must travel, they need to take precaution to prevent exposure to mosquito bites.

About 80 percent of people who are infected with Zika virus may not have any symptoms. Illness may develop in 20 percent of infected people within 3 to 7 days after a bite from an infected mosquito. Symptoms are generally mild and can last for several days to a week. Severe symptoms and fatalities are uncommon.

Common symptoms of Zika virus infection include

  • fever
  • rash, joint pain
  • conjunctivitis (red eyes)
  • muscle pain
  • headache

There is no vaccine, prophylactic or specific medication treatment for Zika virus illness. Supportive care is recommended.

There are currently 37 confirmed cases of Zika Virus in Wisconsin. All of these cases are related to travel to high-risk areas.

For more information on Zika visit: and


Ebola Virus Disease

The CDC has procedures in place to try to prevent ill passengers from getting on a plane in West Africa. The CDC also has protocols if an ill passenger were to travel to the United States.

If you are planning to travel outside the United States:

  • Discuss your travel plans with your health care provider before you go.
  • Check the CDC Traveler’s Health website for updates on travel notices for specific diseases and countries.

After you return from a trip outside the United States:

  • Call your doctor or clinic right away if anyone gets a fever, headache, joint and muscle aches within three weeks of returning home.
  • Tell your doctor where you traveled, what you did, and if you had contact with anyone who had Ebola.

For more information on Ebola and travel recommendations visit: and