Laboratory surveillance for wild and vaccine-derived polioviruses, January 2003-June 2004.

In 1988, the World Health Assembly resolved to eradicate poliomyelitis globally by 2000. Progress toward achieving this goal has been reported from countries where polio is endemic, and three World Health Organization (WHO) regions (Americas, Europe, and Western Pacific) appear to be free of indigenous wild poliovirus (WPV) transmission. One key strategy for eradicating polio is establishing sensitive polio surveillance systems by investigating acute flaccid paralysis (AFP) cases. To ensure that specimens from persons with AFP undergo appropriate processing for viral isolation, WHO established a global polio laboratory network in 1988. This report updates previous publications, summarizes the laboratory network's performance, and describes the location and characterization of WPV and vaccine-derived poliovirus (VDPV) during January 2003-June 2004.