Manish Swarup / AP
Polio vaccination team members update their records after administering polio drops to a child, center, on the outskirts of Ghaziabad in the Indian state of Uttar Pradesh on Jan. 25.
Narinder Nanu / AFP - Getty Images
A boy receives anti-polio vaccination drops from a health worker as part of a polio vaccination campaign in Amritsar, India on Jan. 23. Polio is a pandemic threat in four countries, namely India, Afghanistan, Pakistan and Nigeria, compared to 125 countries in 1988. There were 1,606 cases of polio in 2009, down from about 350,000 in 1988.
In just five days last month, 2 1/2 million health workers visited 68 million homes across India to inoculate 172 million children against polio.