Poliomyelitis

Poliomyelitis (from the Greek polio (πολίός), meaning gray, myelon (µυЄλός), referring to the spinal cord, and -itis denotes inflammation) often called polio or infantile paralysis, is an acute viral infectious disease spread from person-to-person, primarily via the fecal-oral route. While roughly 90% of polio infections are asymptomatic, affected individuals can exhibit a range of more severe symptoms if the virus enters the blood stream. In less than 1% of polio cases the virus enters the central nervous system (CNS), preferentially infecting and destroying motor neurons. The destruction of motor neurons causes muscle weakness and acute flaccid paralysis.

While polio-like symptoms have been identified in ancient cultures retrospectively, poliomyelitis was first recognized as a distinct condition by Jakob Heine in 1840. In the early 20th century much of the world experienced a dramatic increase in the number of polio cases, leading to a series of epidemics. These epidemics—which left thousands of children and adults paralyzed—provided the impetus for a "Great Race" towards the development of an effective vaccine. The development of polio vaccines by Jonas Salk (1955) and Albert Sabin (1962), are credited with reducing of the annual number of polio cases from many hundreds of thousands to around a thousand today. In recent years enhanced vaccination efforts led by the World Health Organization, UNICEF and Rotary International may soon result in global eradication of the disease.