Enterovirus species B isolates recovered from children with acute flaccid paralysis in Nigeria, 2010 and 2012

In 2010 and 2012, between June and October (the peak period of enterovirus circulation in Nigeria), 59 archived enterovirus isolates (recovered as part of the Acute Flaccid Paralysis surveillance program) were randomly selected and typed in this study. All isolates were subjected to RNA extraction, cDNA synthesis and VP1 amplification (nested) and sequencing. Of the 59 isolates, 45 (21 and 24 of the isolates from 2010 to 2012, respectively) had the expected band size (∼350 bp). Forty-three (43) (19 and 24 from 2010 to 2012, respectively) of the amplicons generated were successfully identified and all typed as Enterovirus species B (EV-B) members belonging to twenty (20) different types. The most commonly detected were Echovirus 11 (E11) (9 isolates) and E30 (4 isolates). Many EV-B clades detected show evidence of cross-border transmission in humans within Africa and international spread. Evidence of possible zooanthroponosis/anthropozoonosis between human and nonhuman primates in one EV-B lineage is also reported.