On Aug. 5, the Michigan Department of Agriculture and Rural Development (MDARD) confirmed an unvaccinated yearling Paint gelding as the state’s first reported case of Eastern equine encephalomyelitis (EEE) for 2019. According to a statement, the yearling developed clinical signs of fever and recumbence (inability to rise) on July 22 and was subsequently euthanized.

On July 11, MDARD had warned of heightened concerns about EEE activity, due to both excessive spring and summer rainfall and disease trends that show outbreaks can occur every nine to 10 years, the statement said. The last outbreak in 2010 involved 56 confirmed cases.

MDARD urged horse owners to work with their veterinarians to protect their horses from EEE and West Nile virus (WNV) by vaccinating.

EEE is caused by viruses found in wild birds. Mosquitoes that feed on birds infected with EEE can transmit the disease to humans, horses, and other birds. Some birds can harbor the EEE viruses without becoming acutely ill, thereby serving as reservoirs for the disease. Horses do not develop high enough levels of these viruses in their blood to be contagious to other animals or humans. Because of the high mortality rate for horses and humans, EEE is regarded as one of the most serious mosquito-borne diseases in the United States