Definition, cause and occurrence of polio

Poliomyelitis (usually called polio) is a viral disease that causes paralysis (weakness or inability to use the muscles) of the legs, arms or hands. Polio is caused by three types of viruses, namely, poliovirus types 1, 2 or 3; (note that 'poliovirus' is all one word). Many countries agreed in 1988 to try to eradicate polio completely from the world. As a result of a continuing worldwide vaccination programme, polio is fortunately becoming a rare disease in most developing countries.