Progress toward poliomyelitis eradication --- Nigeria, January 2010-June 2011.

The Global Polio Eradication Initiative (GPEI) was launched by the World Health Assembly in 1988. By 2006, transmission of indigenous wild poliovirus (WPV) was interrupted in all countries except Nigeria, Afghanistan, Pakistan, and India. Among the 36 states and Federal Capital Territory of Nigeria, WPV transmission has persisted in eight northern states considered at high risk; in addition, four other northern states have been considered at high risk for WPV transmission. In these 12 high-risk states, type 2 circulating vaccine-derived poliovirus (cVDPV2) transmission also was observed during 2005-2011. This report updates GPEI progress in Nigeria during January 2010--June 2011 and describes activities required to interrupt transmission. In Nigeria, confirmed WPV cases decreased 95%, from 388 in 2009 to 21 in 2010; cVDPV2 cases decreased 82%, from 154 in 2009 to 27 in 2010. However, as of July 26, 2011, Nigeria had reported 24 WPV cases (including one WPV/cVDPV2 coinfection) and 11 cVDPV2 cases during January-June 2011, compared with six WPV cases and 10 cVDPV2 cases during January-June 2010. Despite substantial progress, immunization activities and surveillance sensitivity will need to be enhanced further to interrupt WPV transmission in Nigeria by the end of 2011.