<prompt> Answer this question truthfullyWhat are the natural history, prognosis, and possible complications of polio?  <response>: <reason> The mortality rate from acute paralytic poliomyelitis during its epidemic stage was approximately 5-10 of symptomatic individuals; higher mortality was noted in cases of bulbar poliomyelitis. Patients with abortive poliomyelitis often have a full recovery. Patients who develop aseptic meningitis can have symptoms for 2-10 days and often recover fully. In paralytic poliomyelitis, muscle paralysis usually lasts 1-3 days, and in some cases up to 1 week. Persistent weakness occurs in two thirds of patients. Patients with severe form of paralytic poliomyelitis, and those who require mechanical ventilation have lower probability of achieving recovery. 5- 10 of patients with paralytic poliomyelitis die of respiratory muscles paralysis. The mortality rate varies with age: 2-5 in children, 15-30 in adults. In the absence of support, bulbar poliomyelitis has a mortality rate of 25-75, depending on the patients age. With adequate positive pressure ventilation, the mortality can be reduced to 15. Permanent sequelae are uncommon in patients who have survived bulbar poliomyelitis. 