Less than two months ago, we reported on the first case of Eastern equine encephalitis virus (EEEV) in the state of Florida in a Polk County Quarter Horse.

Eastern equine encephalitis virus /CDC
Eastern equine encephalitis virus /CDC

On Monday, the fourth EEEv case was reported in a horse in the Sunshine State, this time in Palm Beach County.  The 14 month old, vaccinated Arabian had just moved within the county but had not been outside Palm Beach County since birth. Clinical signs began on May 31 and the horse was euthanized for humane reasons the same day. This is the first confirmed EEE case in Palm Beach County and the fourth confirmed case in Florida for 2016.

Previous cases of EEEv were reported in Osceola County and two cases in Polk County.

EEE is a mosquito-transmitted disease that is much more severe than West Nile Virus (WNV).  The mortality rate in horses from WNV is reported at around 30%, while the rate for EEE is almost 90%.  Infected mosquitoes are the primary source for EEE.

The virus causes inflammation or swelling of the brain and spinal cord.  General symptoms include central nervous system signs such as: head pressing, convulsions, lack of response to facial stimulation, fever above 103 degrees, ataxia, paralysis, anorexia, depression and stupor.  Other symptoms may include irregular gait, teeth grinding, in-coordination, circling, and staggering.  All symptoms may not be exhibited by an infected horse.