Polio: nearly eradicated by immunization

Poliomyelitis (polio) is a highly infectious viral disease that invades the nervous system and causes paralysis. It most often strikes children under the age of 5. Although there is no known cure for polio, immunization is extremely effective.

In 1988 the World Health Organization (WHO) began an initiative to eradicate the virus by 2000 (subsequently revised to 2005). Since the initiative was launched, the number of cases has fallen by 99.9%, from 350,000 new cases in 1988 to 483 in 2001. During the same period, the countries reporting infections have dropped from 125 to 10.

As the graph shows, immunization covered more than 70% of children by 1989. In turn, incidence rates have plummeted quickly.  The maps (below) reflect the rise in immunization and the dramatic drop in incidence worldwide.

The disease continues its foothold in some parts of Sub-Saharan Africa and South Asia.   In 2001, five countries accounted for 85% of all new polio cases: India, Pakistan, Afghanistan, Niger and Nigeria.  Several other areas had a lower rate of transmission: Somalia, Sudan, Ethiopia, Angola and Egypt. Though the total number of cases in the world is now very small, the incidence remains high in some select areas. For example, the Indian State of Uttar Pradesh accounted for 68% of the worldwide cases (Waldman, 2003). In this case, Waldman found that many parents have refused to immunize their children, after hearing false rumors about side effects of the vaccines.

However, WHO continues to persist in their goal of total eradication. Their view is that as long as a single child remains infected, children in all countries are at risk of contracting the disease.  Eradication of the disease exemplifies health equality, because it will reduce the risk for all people, regardless of economic or social status.

References

Waldman, Amy (2003). Polio makes comeback in India, assisted by rumors and distrust      The New York Times

Links

WHO Polio Fact Sheet

http://www.who.int/mediacentre/factsheets/fs114/en/

WHO Health Topic Page: Polio

http://www.who.int/health_topics/poliomyelitis/en/

WHO Vaccines, Immunizations and Biologicals

http://www.who.int/vaccines-surveillance/StatsAndGraphs.htm