Poliomyelitis is a viral infection caused by any of three serotypes of human poliovirus, which is part of the family of enteroviruses.
Progress in global poliomyelitis eradication, since its beginning in 1988, has been remarkable. In 1988, 125 countries were endemic for poliomyelitis and an estimated 1000 children were being paralyzed every day by wild poliovirus. By the end of 2003, six polio-endemic countries remained (Afghanistan, Egypt, India, Niger, Nigeria, Pakistan), and less than 3 children per day were being paralyzed by the poliovirus. The Global Poliomyelitis Eradication Initiative is ongoing. There remain only 4 endemic countries (Pakistan, Afghanistan, India, and Nigeria) and just 2000 reported cases globally in 2006.
It primarily affects children under the age of 5. Generally the infection is limited to the grastrointestinal tract and nasopharynx and is often asymptomatic. The central nervous system, primarily the spinal cord, may be affected, leading to rapidly progressive paralysis. Motor neurons are mainly affected. Encephalitis may also occur.
Transmission is mainly person-to-person, principally through the fecal-oral route. The virus replicates in the nervous system and particularly affects motor neurons in the anterior horn of the spinal cord (`polio' means `gray').
Poliomyelitis must be distinguished from other paralytic conditions by isolation of virus from stool.
Prevention is the only cure for paralytic poliomyelitis. Two vaccines against poliomyelitis are available: an inactive injectable vaccine and a live attenuated vaccine that is taken orally. Europe was certified as polio-free in June 2002 and immunization and disease surveillance continue to ensure the region remains polio-free
Last update: January 2010
- Dr Bruce AYLWARD
- Dr David HEYMANN