Polio

Poliomyelitis, commonly called polio, is an infectious disease caused by infection with poliovirus, a member of the enterovirus family. There are three serotypes (PV1, PV2, PV3). The virus spreads mainly through the fecal-oral route and, less commonly, through oral-oral contact. After an incubation period of about seven to fourteen days, most infections are asymptomatic or cause a mild febrile illness; a small proportion progress to more severe disease.

Paralytic polio is rare but disabling. It produces acute flaccid paralysis that is asymmetric and non-sensory; most often it affects the legs, but it can involve the muscles of the arms or the muscles that control breathing and swallowing if the brainstem is affected (bulbar poliomyelitis). Nonparalytic poliomyelitis can cause aseptic meningitis. Some people who survive polio may later develop post-polio syndrome years after recovery, with fatigue and progressive muscle weakness.

Diagnosis is based on clinical presentation and exposure history; confirmation is through laboratory detection of poliovirus or poliovirus antibodies in stool, throat swabs, or cerebrospinal fluid. Vaccination status helps inform the likelihood of polio and the need for testing.

There is no Cure for polio; treatment is supportive. Management focuses on preventing complications, maintaining hydration and nutrition, physical therapy to preserve muscle strength, and respiratory support when needed.

Prevention is achieved primarily through vaccination. Two vaccines exist: the inactivated polio vaccine (IPV), given by injection, and the oral polio vaccine (OPV), given by mouth. OPV can, rarely, lead to vaccine-derived poliovirus outbreaks, which affects vaccination policy and surveillance decisions. High vaccination coverage and ongoing surveillance have driven the near-elimination of wild poliovirus transmission in many regions, but continued immunization is essential to prevent re-emergence.