Environmental Isolation of Circulating Vaccine-Derived Poliovirus After Interruption of Wild Poliovirus Transmission - Nigeria, 2016.

What is known about this topic? The last case of wild poliovirus transmission in Nigeria was reported in July 2014. The country was officially removed from the list of countries with endemic wild poliovirus transmission in September 2015. What is added by this report? In April 2016, a laboratory-confirmed isolate of circulating vaccine-derived poliovirus type 2 (cVDPV2), a genetic variant of the vaccine virus with the potential to cause paralysis, was reported from a sewage effluent site in Borno, a state in northeastern Nigeria with international boundaries. Years of armed insurgency in Borno have led to reduced polio vaccination and surveillance activities, resulting in a population of underimmunized children. The Nigeria National Polio Emergency Operations Center activated an outbreak response that included supplemental immunization activities (SIAs), a retrospective search for acute flaccid paralysis (AFP) cases, and enhanced environmental surveillance. Approximately 1 million children were vaccinated in the first SIA round, and 13 previously unreported AFP cases were identified. What are the implications for public health practice? Strategies for increasing vaccination coverage, including deployment of innovative approaches for reaching children in conflict-affected areas, are needed to prevent VDPV and other vaccine preventable disease (VPD) outbreaks. Strengthening surveillance is an urgent priority. Closer coordination of polio eradication activities between state and national jurisdictions in the region should be considered to prevent the potential spread of cVDPV and other VPDs across international boundaries.