In the past 20 years the number of polio cases in the world have decreased significantly. Between 2000 and 2005 the worldwide number of new polio cases fell from 2971 to 155. In 2005, polio was detected in just 9 territories.
India and Nigeria recorded the most cases of polio between the years 2000 and 2005. Over this period there were 2508 cases in India and 2120 in Nigeria. Most territories had no new cases so they cannot be seen on the map.
Polio, or poliomyelitis, is a virus which can permanently paralyse groups of muscles. The disease cannot be cured, it is possible to vaccinate against it. Polio usually affects children under 5 years old.