Cherokee Animal Clinic
P O Box 416
665 Johnson Street
Rusk, TX 75785
Clinic Hours:
Monday - Friday 7:30 am - 5:30 pm

Eastern - Western - Venezuelan

Enceplahlitis is an infectious disease of horses caused by any of several viruses, which can also infect humans. The viruses, which begin their life cycles as parasites of wild birds, are transferred to horses, and from horses to humans, in the salivary glands of mosquitos. The disease, for which no specific treatment is known, can be prevented by annual vaccination of horses. Equine encephalitis is a serious public-health problem in N South America. In 1991 the Eastern virus infected horses throughout much of the SE United States; five infections of humans occurred in Florida. In 1992 the virus was first identified in the Asian tiger mosquito, an aggressive feeder on both horses and humans.

The Eastern and Western encephalomyelitis viruses are transmitted mainly by mosquitoes. Normally, these two viruses cycle between birds and mosquitoes. Humans and horses are incidental, dead end hosts.

The Venezuelan equine encephalomyelitis viruses are also spread mainly by mosquitoes. The enzootic subtypes of VEE cycle between rodents and mosquitoes, mainly Culex species. Birds may also be involved in some cycles. Humans and horses are incidental hosts.


The symptoms of equine encephalitis include fever, drowsiness, and incoordination, often followed by paralysis and death. The mortality rate is 90%, usually within 2 to 3 days, in the most virulent, Eastern type; and as high as 50% in the Western type. There is no specific treatment.

Prevention is the key! Be sure all water filled containers that may harbor mosquitos be empty.


Contact our office to set up a vacination schedule for your equine family!

Care Credit