Available vaccines are inexpensive, safe, and provide good protection. WEE has been noted throughout North America, while EEE appears only in the east and southeast. VEE, the Venezuelan variety, has not been seen in the United States for many years. However, a recent outbreak of VEE occurred in Mexico. Sleeping sickness is most often transmitted by mosquitos, after the insects have acquired the virus from birds and rodents.
Symptoms vary widely, but all result from the degeneration of the brain.
Early signs include fever, depression, and appetite loss. Later, a horse might stagger when it walks, and paralysis develops in later stages. All horses need an EEE and WEE vaccine at least annually. Pregnant mares and foals may require additional vaccinations. The best time to vaccinate is spring, before the mosquitos become active.