Polio, or poliomyelitis, is an infectious disease caused by the poliovirus that has existed for thousands of years. Its origins are ancient, with evidence of the disease found in Egyptian art depicting withered limbs, and the earliest known cases traced back about 4,000 years ago. The disease only affects humans and is transmitted primarily through the fecal-oral route. Major polio epidemics did not appear until the late 19th and early 20th centuries, coinciding with improved sanitation that delayed early childhood exposure to the virus, reducing passive immunity from mothers and increasing the risk of paralysis. The infectious agent, poliovirus, was first identified in 1908 by Karl Landsteiner and Erwin Popper.
Summary of polio's origin and history:
- Ancient disease existing thousands of years ago; evidence from Egyptian carvings (~1400 BCE) and skeletal deformations dated thousands of years back.
- Affected only humans, caused by poliovirus, an RNA virus infecting the gastrointestinal tract.
- Epidemics became common in the 20th century due to hygiene improvements that disrupted early immunity in infants.
- The term poliomyelitis derives from Greek, meaning inflammation of the grey matter of the spinal cord.
- Poliovirus identified in 1908; major research and vaccine development followed in the 20th century.
Thus, polio originated as an ancient human virus with historical presence for millennia, emerging into widespread epidemics in modern times due to changes in human living conditions and hygiene practices.
