Progress toward interruption of wild poliovirus transmission – worldwide, 2009

In 1988, an estimated 350,000 cases of poliomyelitis were occurring annually worldwide. By 2005, because of global vaccination efforts, indigenous transmission of wild poliovirus (WPV) types 1 and 3 (WPV1 and WPV3) had been eliminated from all but four countries (Afghanistan, India, Nigeria, and Pakistan). No cases of WPV type 2 have been reported since 1999. This report describes progress toward global WPV eradication during 2009 and updates previous reports. During 2009 a total of 1,606 cases of WPV infection were reported, compared with 1,651 in 2008. WPV3 incidence increased 67%, to 1,124 cases, compared with 675 in 2008. However, WPV1 incidence decreased 51%, to 482 cases in 2009, compared with 976 cases in 2008. In India, nearly all polio cases in 2009 were reported in high-risk districts in western Uttar Pradesh and central Bihar. In Afghanistan and Pakistan, WPV circulation in high-risk districts continued because of difficulties vaccinating children in conflict-affected areas and operational limitations in parts of Pakistan. In Nigeria, cases decreased by 51%, to 388 cases in 2009, compared with 798 in 2008. During 2009, outbreaks from importation of WPV affected 19 previously polio-free African countries. Two key steps are needed to make further progress in polio eradication: 1) addressing local barriers to interrupting transmission, and 2) using bivalent oral poliovirus vaccine (bOPV) broadly for WPV 1 and 3 in supplemental immunization activities (SIAs).