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Equine Encephalitis find in Polk County prompts vaccination warning

The discovery of EEE or Easter equine encephalitis in a Polk County quarter-horse has prompted a widespread warning from state health officials for humans to take increased precautions.

MADISON - A confirmed case of equine encephalitis in a Polk County horse has state health authorities advising horse owners to get their animals vacinated and take steps to minimize their animals' exposure to mosquitoes.

Blood samples from a quarter horse were submitted to Wisconsin Veterinary Diagnostic Laboratory on Aug. 30 and confirmed Friday.

Dr. Robert Ehlenfeldt, the state veterinarian, issued a warning Aug. 21 after his office received notification that two horses in Clark and Lincoln Counties had been sickened with EEE or Eastern equine encephalitis

The latest confirmation has prompted another warning from Ehlenfeldt and a health advisory from the Wisconsin Department of Health Services.

"Vaccinate your horses if you haven't already, or get boosters for those you vaccinated earlier in the year," says assistant state veterinarian Dr. Paul McGraw. "EEE has a mortality rate in excess of 90 percent. The vaccine is not expensive, it's effective, and if we've found EEE in these three counties, it's reasonable to assume it's more widespread. Unless we have a really early killing frost, we still have a lot of mosquito season ahead of us."

In addition to vaccination, horse owners can take steps to reduce their animals' exposure to mosquitoes. If possible, owners should also keep their animals inside barns if possible from dusk through dawn, when mosquitoes are most active.

Symptoms in horses include depression, loss of appetite, drooping eyelids and lower lip, aimless wandering and circling, blindness and sometimes paralysis. There is no cure for horses; the disease must run its course. Most animals die or must be euthanized, but a few recover.

EEE is caused by a virus transmitted by mosquito bite to horses, birds, and humans. The virus is not transmitted between animals or between animals and humans but the presence of an EEE positive horse confirms that there are infected mosquitoes in the area that could possibly transmit the virus to people and other animals.

Most people infected with the EEE virus do not have symptoms, according to Dr. Henry Anderson, state health officer. 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, other than treating symptoms.

People who suspect they have EEE illness should contact their healthcare provider.

EEE and West Nile virus are both currently circulating, and Wisconsin residents and state visitors should take measures to prevent mosquito bites. 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 these measures to protect themselves:

• Maintain window screens in good repair to decrease indoor contact with mosquitoes.

• Avoid being outside during times of high mosquito activity, specifically around dawn and dusk.

• Wear protective clothing such as long pants, loose-fitting long-sleeved shirts.

• When outdoors, consider using an effective mosquito repellent .

• Minimize breeding sites for mosquitoes--remove containers, old tires, unused wading pools, and any objects where water can collect and mosquitoes can lay eggs.

• Empty standing water from bird baths. Trim tall grass, weeds and vines because mosquitoes use these sites to rest during hot daylight hours.

• Clean gutters and downspouts to ensure they drain properly.

In 2011, the EEE virus caused one reported human illness (which was fatal) and 34 reported animal deaths (31 horses, 2 alpacas, and 1 pheasant). The human EEE case was only the second case known to have occurred in Wisconsin since 1984.

For information about EEE virus, visit: