Progress toward interruption of wild poliovirus transmission--worldwide, January 2011-March 2012.

In January 2012, completion of polio eradication was declared a programmatic emergency for global public health by the Executive Board of the World Health Organization (WHO). Despite major progress since the launch of the Global Polio Eradication Initiative (GPEI) in 1988, circulation of indigenous wild poliovirus (WPV) continues in three countries (Afghanistan, Nigeria, and Pakistan). India has not reported a polio case since January 2011, and is considered polio-free since February 2012. This report highlights progress toward global polio eradication during January 2011-March 2012. The number of polio cases reported globally decreased by 52%, from 1,352 in 2010 to 650 in 2011. Those 650 cases included 341 (53%) reported from the four polio-endemic countries (Afghanistan, India, Nigeria, and Pakistan), 230 (35%) from previously polio-free countries in which WPV importations led to reestablished transmission for ≥12 months (Angola, Chad, and Democratic Republic of the Congo [DRC]), and 79 (12%) from nine countries affected by outbreaks. Compared with 2010, WPV cases increased in 2011 in Afghanistan (69%), Nigeria (66%), and Pakistan (27%), but decreased in India (98%). During January-March 2012, 59% fewer cases were reported worldwide (as of May 15) compared with the same period in 2011, and all cases in 2012 have been reported from Afghanistan, Chad, Nigeria, and Pakistan. Although progress toward polio eradication was substantial in 2011, persistent WPV circulation in 2012, particularly in Nigeria and Pakistan, poses an ongoing threat to eradication efforts, underscoring the need for emergency measures by polio-affected countries and those at risk for outbreaks after importation.