Initially, it produces a mild or symptomless systemic infection. At this stage, most people produce antibodies and eliminate the virus. In a small percentage of patients, the virus is not killed, and it spreads to the spinal cord and brain, causing fever, headache and stiffness, followed by mild to severe muscular weakness. Fatality can occur from respiratory paralysis. Treatment consists of supportive care, analgesics for muscle pain, and support for severely weakened muscles to prevent limb distortion.
Convalescence can be prolonged and consists of muscle retraining and massage.
How the Disease Is Transmitted Knowledge of the symptoms of poliomyelitis and its mode of transmission was obtained by studying human patients, beginning as far back as 1840, when Jacob von Heine provided the first detailed description of the disease. The virus was found in the contents and walls of human small intestines, suggesting transmission via the digestive tract. 1 Population studies led to the theory of naturally acquired immunity, which held that exposure to the virus causes immunity to later infection. Antibodies, indicating immunity to the poliovirus, were found in healthy and convalescing patients. A few years later, researchers at Johns Hopkins and Yale detected the virus in patients' blood before neurological signs were seen.