Surveillance for acute flaccid paralysis in Yulin, Guangxi, 2008-2013

Objective To understand the epidemiological characteristics of acute flaccid paralysis (AFP) in Yulin, Guangxi zhuang autonomous region, from 2000 to 2013 and provide evidence to maintain polio-free status in Yulin. Methods Virus isolation and identification were conducted for all the AFP cases reported in Yulin from 2000 to 2013 according to the requirements of WHO. Results Among 451 AFP cases reported during this period, 13 strains of polio virus (2.88%) and 39 strains of non-polio enteroviruses (8.65%) were isolated. Intratypic differentiation was conducted for 13 polio virus strains, and 1 strains of vaccine derived polio virus (VDPV) was detected, the others were vaccine related viruses, including 7 type Ⅱ strains, no wild polio virus was detected. Polio virus and non-polio enteroviruses could be detected all the year round, but the isolation rate of polio virus was high in December. The polio positive cases were distributed in all the counties, except Luchuan, and Xingye. The polio virus detection rate was highest in age group 1 year (11.90%), followed by age groups 1-4 years (9.60%) and 4 years (4.27%). The polio virus detection rate in AFP cases receiving all the doses of oral polio vaccine (OPV) was lower than those receiving incomplete OPV immunization. Conclusion No wild polio virus circulation was found in Yulin during 2000-2013, the polio free status was maintained. It is still necessary to strengthen local AFP surveillance to contribute to global polio eradication.