The New Hampshire Department of Health and Human Services yesterday (Sept. 20) announced positive test results for Eastern equine encephalitis (EEE) in a horse in the Hillsborough County town of Derry. Two emus in the Cheshire County town of Fitzwilliam also tested positive. The horse and emus are the first animals to test positive for the disease this year.

"These results highlight the fact that these illnesses affect not just mosquitoes, but animals and of course people too," said New Hampshire’s Public Health Director José Montero, MD. "It is also an indication that mosquitoes do not respect borders, and as a result can infect animals and people in any corner of our State. We know this has been a particularly bad season for both EEE and West Nile virus (WNV). In fact, in our bordering states there have been several deaths reported as a result of EEE."

A viral disease, EEE affects the central nervous system and is transmitted to horses by infected mosquitoes. Its fatality rate in horses is 75-95%. The course of EEE can be swift, with death occurring two to three days after onset of clinical signs despite intensive care. Horses that survive might have long-lasting impairments and neurologic problems. Clinical signs of EEE include moderate to high fever, depression, lack of appetite, cranial nerve deficits (facial paralysis, tongue weakness, difficulty swallowing), behavioral changes (aggression, self-mutilation, or drowsiness), gait abnormalities, or severe central nervous system signs, such as head-pressing, circling, blindness, and seizures.

Vaccinations are available for both diseases, and the American Association of Equine Practitioners recommends all horses receive both annually. Horses with clinical signs of WNV or EEE should be evaluated by a veterinarian immediately