The Virginia Department of Agriculture and Consumer Services (VDACS) has announced the second case of Eastern Equine Encephalitis (EEE) in a Virginia horse this year. The horse, a three-year-old Tennessee Walker mare, was from Chesapeake and had been purchased by the owner only three weeks ago. The horse's vaccination history is unknown.
More mosquito-borne diseases in horses
Eastern equine encephalitis and West Nile virus are both mosquito-borne diseases that can be deadly for horses and vaccinations have proven to be the best prevention method along with careful biosecurity measures.
The horse exhibited signs August 13 and was euthanized August 14 due to the severity of the illness. VDACS received confirmation from the National Veterinary Services Laboratory in Ames, Iowa on August 21. Both cases of EEE this year have been in horses from Chesapeake.
EEE virus attacks the central nervous system and unvaccinated horses are very susceptible to the infection. The disease appears within five days after a mosquito transmits the virus to the horse. Onset of clinical symptoms are abrupt and infected horses often die within three days.
The fatality rate is 90% or higher and an animal that survives the disease may have brain damage.
Other diseases and poisoning may have similar symptoms. It is important that a speedy diagnosis is made. A veterinarian can take blood samples to send to a diagnostic laboratory.
The first 2015 Equine West Nile case in New Mexico was confirmed on August 20, 2015 in an unvaccinated 4 year--old Valencia County mustang mare. The horse first demonstrated clinical neurologic signs of disease on August 13, 2015. The horse is under veterinary care and has shown improvement with partial resolution of clinical signs of disease. Horse owners are encouraged to consult with their veterinarians to ensure that annual vaccination for WNV is part of their horse health plan.
West Nile virus is a mosquito-borne zoonotic disease that affects both horses and humans. In horses that become clinically ill, the virus infects the central nervous system and causes symptoms of encephalitis.
The case fatality rate for horses exhibiting clinical signs of WNV infection is approximately 33%. Data have supported that 40% of horses that survive the acute illness caused by WNV still exhibit residual effects, such as gait and behavioral abnormalities, 6-months post-diagnosis.