Nucleotide Variation of Poliovirus Isolated From Acute Flaccid Paralysis Cases in Hebei Province,2009-2011

Objective To analysis the VP1 nucleotide variation of poliovirus isolated from acute flaccid paralysis(AFP) cases and close contacts in Hebei province during 2009-2011,so as to detect vaccine-derived poliovirus(VDPV) and Circulating VDPV(VDPVs) timely and provide the evidence for maintaining polio free status.Method All stool samples from acute flaccid paralysis(AFP) cases and close contacts were virally isolated and identified according to the World Health Organization(WHO) Polio Laboratory Manual and then performed VP1 sequencing.Results During 2009-2011,24 cases AFP cases and 7 cases of AFP close contact were isolated with poliovirus.After single type isolation from the mixed,38 single type were obtained,and 36 strains of which occurred mutation with VP1 gene nucleotide,with a mutation rate under 10%.Poliovirus positive cases were higher in males than that in females and mainly in low age groups.Conclusion During 2009 to 2011,the polioviruses were all vaccine strains.The high variability of the virus appeared in local areas;vaccine derived polio virus case were not found.Hebei province continues to maintain the polio-free status.