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→Clinical Signs
====Clinical Signs====
====Clinical Signs====
The incubation of the disease after infection with the virus is from 1 to 3 weeks. In the initial stage there is fever, which may be accompanied by depression, and loss of appetite, but the reaction may be so mild it goes unnoticed. The virus causing Eastern Equine Encephalomyelitis (EEE) is the most virulent of the three types and the symptoms produced are the most severe, with a case fatality rate of up to 90%. The viraemia (level of virus in the blood) may be so high with this strain that horse to mosquito to horse cycling can occur.
The nervous signs, when they appear, are hypersensitivity to sound and touch with periods of excitement and restlessness with apparent blindness. Affected horses may walk blindly into objects or walls. Muscle twitchings may occur in the face and shoulder muscles. A period of severe depression follows. Affected horses stand with their heads hung low and may have a half-chewed mouthful of feed hanging from their lips. The animal appears to be asleep and is unable to hold up his head and often rests it on some solid object.
Although VEE does not cause as high a mortality as WEE/EEE, the clinical signs are similar. However, a second generalised infection may be caused by the virus causing fever, depression, colic and diarrhoea.
Worse in unvaccinated animals. Acute signs of EEE and WEE are nonspecific, last up to 5 days and include:
Worse in unvaccinated animals. Acute signs of EEE and WEE are nonspecific, last up to 5 days and include:
*mild to severe pyrexia
*mild to severe pyrexia