Polio, short for poliomyelitis, is an acute and potentially devastating disease caused by a virus. Humans are the virus's sole natural host. It enters the body through the mouth, replicating in the throat and intestinal tissues. A small amount of the virus then enters the bloodstream, spreading to other areas where it multiplies further. A subsequent wave of viremia, or virus in the blood, allows it to invade the central nervous system (CNS), particularly targeting the spinal cord and brain.In polio, inflammation primarily affects the horn cells of the spinal cord and the brainstem, the area connecting the cerebral hemispheres and the spinal cord. Often, polio presents as a minor illness, especially in 80-90% of young children with clinical infections, not involving the CNS. Symptoms include mild fever, headache, fatigue, and vomiting within 3-5 days of exposure, with recovery typically occurring within 24-72 hours. This is known as the abortive type of polio.As a major illness, polio can be paralytic or non-paralytic. Symptoms often appear in older children and adults, 7-14 days post-exposure, with no preceding illness. These symptoms include fever, a severe headache, stiff neck and back, deep muscle pain, and occasionally areas of heightened or altered sensation. The disease may not progress beyond this stage of viral meningitis, or it may lead to a loss of reflexes and muscle weakness or paralysis. While recovery is usually complete in the abortive and non-paralytic forms, paralytic polio results in about 50% of patients recovering without residual paralysis, 25% with mild disabilities, and the rest with severe, permanent disability. Most muscle function returns in the first six months, though improvement can continue for up to two years. Rehabilitation is crucial during the recovery phase of paralytic polio. The best approach is prevention through vaccination against the poliovirus.U.S. President Franklin D. Roosevelt, who had polio, collaborated with the National Foundation/March of Dimes to raise funds to fight this once-dreaded disease. Polio is also referred to as infantile paralysis.
