Detection of acute flaccid paralysis(AFP) cases and poliovirus in Shaanxi province

Objective To analyze the epidemiological character of AFP cases and to detect poliovirus in Shaanxi province during 2003-2008 in order to increase the sensitivity of vaccine derived poliovirus(VDPVs) surve illance.Methods Epidemiological analysis was conducted in A FP cases with positive poliov irus detection and VP1 genomic sequencing technique was used to analyze the molecular character of vaccine variant polio viruses.Results From 2003 to 2008,29 poliov irus strains were isolated from AFP cases,and the number of type Ⅰ strains exceed to the summation of type and type Ⅱ strains.75.86% of cases were children.The main paralysis parts of body were single or both lower extremity and lmibs.Fourteen strains were indentified as vaccine variant poliovirus.The vaiant rate of VP1 sequence did not reach 1%.Among these cases,7 cases were not fully vaccinated children and 9 were under 2 years old.Conclusion VD-PV emergence and cVD-PVs circulation still possibly occur in course of polio eradication.It is important to keep high level surve illance and vaccination coverage.