Polio, short for poliomyelitis, is an infection that can affect nerve cells in the spinal cord. While most infections do not result in illness, severe infections can kill nerve cells. This leaves muscles permanently weak or damaged. About 1 in every 100 persons infected with the virus becomes paralyzed.
Paralytic disease still exists in certain parts of Africa, southeast Asia and India. Until the virus has been eliminated worldwide, the risk to Canadians remains high and immunization in childhood is recommended.
Public Health Agency of Canada. Canadian Immunization Guide. Evergreen edition. http://www.phac-aspc.gc.ca/publicat/cig-gci/index-eng.php (external link)
Canadian Paediatric Society. Polio. http://www.caringforkids.cps.ca/handouts/immunization-index (external link)
- Early 1900s – Epidemics began to occur in Europe and North America. Improved sanitation and hygiene eventually reduced the risk of exposure for infants and children. However, when older children and adults encountered poliovirus, the infection often resulted in paralysis.
- 1951–54 – On the eve of the introduction of polio vaccine, 65,000 cases of paralytic polio were reported in the U.S. alone.
- 1955 – More than 76,000 cases of paralytic polio were reported in Canada, the U.S., the former Soviet Union, Western Europe, Australia and New Zealand.
- 1967 – In the same countries noted above, only 1013 cases were reported – a reduction of 99% in just 12 years through vaccination.
- 1991 – Poliovirus was eradicated from the entire Western Hemisphere.