Laboratory surveillance for wild and vaccine-derived polioviruses, January 2004-June 2005.

A global network of 145 virology laboratories has been established by the World Health Organization (WHO) to support surveillance activities of the Polio Eradication Initiative (PEI). The Global Polio Laboratory Network analyzes stool specimens from patients with acute flaccid paralysis (AFP) and environmental samples for the presence of polioviruses. Surveillance systems detect at least one AFP case per 100,000 persons aged <15 years, collect adequate stool samples from patients, and send the samples to network laboratories for analysis. Laboratory data are used to identify locations where wild polioviruses (WPVs) or vaccine-derived polioviruses (VDPVs) are circulating, target supplementary immunization activities (SIAs) to interrupt transmission chains, and investigate genetic relationships among viral isolates. This report updates previous publications and describes the laboratory network's performance during the period January 2004-June 2005.