Progress toward poliomyelitis eradication--Nigeria, January 2007-August 12, 2008.
Nigeria is one of only four countries that have never interrupted poliovirus transmission (the others are Afghanistan, India, and Pakistan). A resurgence in wild poliovirus (WPV) transmission occurred in Nigeria during 2003-2004 after a loss of public confidence in oral poliovirus vaccine (OPV) and suspension of supplementary immunization activities (SIAs)* in several northern states. Subsequently, WPV spread within Nigeria and ultimately into 20 previously polio-free countries during 2003-2006. Even after national SIAs resumed, limited acceptance and ongoing operational problems resulted in low polio vaccination coverage and continued WPV transmission. Beginning in 2006, health authorities in Nigeria introduced new initiatives to control the spread of WPV, including a focus on interrupting type 1 WPV (WPV1) transmission and use of monovalent type 1 OPV (mOPV1) for most of the SIAs to increase vaccine effectiveness. Nigeria also instituted changes in SIA implementation to increase community acceptance of vaccination. Subsequently, 285 polio cases were reported in Nigeria in 2007, the lowest number since sensitive surveillance has been in place. As of August 12, 2008, confirmed polio cases reported in Nigeria totaled 556 (including 511 WPV1 cases), compared with 176 cases (53 WPV1) reported during the same period in 2007. This report updates overall progress toward polio eradication in Nigeria during 2007-2008. Given the increase in WPV transmission thus far in 2008, urgent measures are needed to reach all children during SIAs to bring WPV under control in Nigeria.