In general,<unk>  is not life-threatening. The major exception are patients left with severe residual respiratory difficulties, who may experience new severe respiratory impairment. Compared to control populations,<unk>  patients lack any elevation of antibodies against the<unk> virus, and because no<unk> virus is excreted in the feces, it is not considered a recurrence of the original<unk> . Further, no evidence has shown that the<unk> virus can cause a persistent infection in humans.<unk>  has been confused with amyotrophic lateral sclerosis (ALS), which progressively weakens muscles.<unk>  patients do not have an elevated risk of ALS. No sufficient longitudinal studies have been conducted on the prognosis of<unk> , but speculations have been made by several physicians based on experience. Fatigue and mobility usually return to normal over a long period of time. The prognosis also differs depending upon different causes and factors affecting the individual. An overall mortality rate of 25% exists due to possible respiratory paralysis of persons with<unk> ; otherwise, it is usually not lethal. Prognosis can be abruptly changed for the worse by the use of anesthesia, such as during surgery.
Post-polio syndrome
Leukomyelitis
Guillain–Barré syndrome
FACES syndrome
Acute disseminated encephalomyelitis
Eastern equine encephalitis
Tension myositis syndrome
Postvaccinal encephalitis