Eastern Equine Encephalitis

What is Eastern Equine Encephalitis? 

Eastern Equine Encephalitis also known as the sleeping sickness, is a viral disease that causes inflammation of the brain and spinal cord. It is transmitted by mosquitoes.

Clinical Signs: Clinical signs and symptoms of eastern equine encephalitis include the following: 

  • Depression and anorexia; initially without a fever when initially infected 
  • Moderate to high fever 
  • Lack of appetite 
  • Lethargy/drowsiness 
  • Neurologic signs- onset of neurologic disease is frequently sudden and progressive 
    • Periods of hyperexcitability, apprehension and/or drowsiness 
    • Fine tremors and fasciculations of the face and neck muscles 
    • Convulsions 
    • Cranial nerve paralysis-facial paralysis and weakness of the tongue are very common 
    • Head tilt, droopy lip, muzzle deviation
    • Weakness, ataxia, and incoordination
    • Complete paralysis of one or more limbs 
    • Colic 
    • Recumbency 
    • Death 

Diagnosis: Diagnosis is made by a veterinarian by measuring titers in serum (a component of whole blood) using an ELISA (enzyme-linked immunosorbent assay) or, less commonly, with PCR or CSF (cerebrospinal fluid). 

Treatment: There is no cure for Eastern Equine Encephalitis. Supportive care is administered in horses which show clinical signs. 

Prevention:  Vaccination for EEE is highly effective and is recommended as a core vaccination.


May 15, 2024
Osceola County, FL
Confirmed Case(s) - No Quarantine
April 29, 2024
Polk County, FL
Confirmed Case(s) - No Quarantine
April 16, 2024
Marion County, FL
Confirmed Case(s) - No Quarantine