| environmental isolation of circulating vaccine-derived poliovirus after interruption of wild poliovirus transmission - nigeria, 2016. | in september 2015, more than 1 year after reporting its last wild poliovirus (wpv) case in july 2014 (1), nigeria was removed from the list of countries with endemic poliovirus transmission,* leaving afghanistan and pakistan as the only remaining countries with endemic wpv. however, on april 29, 2016, a laboratory-confirmed, circulating vaccine-derived poliovirus type 2 (cvdpv2) isolate was reported from an environmental sample collected in march from a sewage effluent site in maiduguri municipa ... | 2016 | 27490081 |