Equine Encephalitis (EE)
A contagious disease of birds, mammals, horses, and people caused by a virus.
Two forms affect birds, eastern and western encephalitis.
All birds are susceptible though EE is rarely diagnosed in confinement reared domestic poultry.
Due to present day transporting of livestock, both disease have been diagnosed across the nation. Generally, each remains endemic to its original areas.
The virus increases in titer in the mosquito, although increased titer is not necessary for transmission.
Birds are the major source of the virus for vectors because birds develop higher titer than mammals. Infected mosquitoes are the primary vectors.
The clinical signs of EEE and WEE are identical, signs include inappetence, staggering and paralysis.
Surviving birds may be blind, have unilateral or bilateral paralysis of muscle groups and difficulty in holding up the head. Damage to the birds central nervous system varies slightly with species. Flock mortality is up to 95%.
Diagnosis is by history, typical microscopic lesions, virus isolation or positive serology. The preferred serological test is virus neutralization using tissue-culture systems.
Prevention is immunize birds with vaccine prepared for horses. Do not immunize birds until 6 weeks of age.