Polio or poliomyelitis is the disease caused by the poliovirus. The virus attacks cells in the spinal cord and causes symptoms of fever, sore throat, headache, vomiting, and stiffness of the neck. Patients with polio can have long-term weakness of muscles as a result of the damaged cells in the spinal cord. Occasionally, patients that recover from the disease can experience a relapse of muscle weakness. This can occur as long as 25-35 years after first having polio. The condition is called "post-polio syndrome".