Nigeria has been reclassified as a country affected by endemic transmission of wild poliovirus type 1 (WPV1).  Nigeria had been removed from the list of endemic countries in September 2015, following a year of no reported/detected WPV1 cases in the country. 
 
 However, the recent cases of WPV1 detected from Borno are closely linked to cases from Borno in 2011, indicating this strain has been circulating undetected since that time.  This indicates that Nigeria has always been affected by endemic circulation of WPV1 and, hence, it is added again to the list of endemic countries, alongside Pakistan and Afghanistan.