Surveillance systems to track progress toward polio eradication — Worldwide, 2015–2016

Global measures to eradicate polio began in 1988; as of 2014, four of six World Health Organization (WHO) regions have been certified polio-free. Within the two endemic regions (African and Eastern Mediterranean), Nigeria, Afghanistan, and Pakistan have never interrupted transmission of wild poliovirus (WPV) (1). The primary means of detecting poliovirus transmission is surveillance for acute flaccid paralysis (AFP) among children aged <15 years, combined with collection and testing of stool specimens from persons with AFP for detection of WPV and vaccine-derived polioviruses (VDPVs) (viruses that differ genetically from vaccine viruses and can emerge in areas with low vaccination coverage and cause paralysis) in WHO-accredited laboratories within the Global Polio Laboratory Network (2,3). AFP surveillance is supplemented by environmental surveillance for polioviruses in sewage from selected locations (4). Genomic sequencing of the VP1-coding region of isolated polioviruses enables mapping transmission by time and place, assessment of potential gaps in surveillance, and identification of the emergence of VDPVs. This report presents poliovirus surveillance data from 2015 and 2016, with particular focus on 20 countries in the African Region and six in the Eastern Mediterranean Region that reported WPV or circulating VDPVs (cVDPVs) during 2011–2016, as well as the three countries most affected by the 2014–2015 Ebola virus disease (Ebola) outbreak (Guinea, Liberia, and Sierra Leone). During 2016, 12 (60%) of the 20 African Region countries and all six of the Eastern Mediterranean Region countries met both surveillance quality indicators (nonpolio AFP rates of ≥2 per 100,000 persons aged <15 years per year and ≥80% of AFP cases with adequate stool specimens [stool adequacy]) at the national level; however, provincial-level variation was seen. To complete and certify polio eradication, surveillance gaps must be identified and surveillance activities, including supervision, monitoring, and specimen collection and handling, further strengthened.