Active surveillance for acute flaccid paralysis in poliomyelitis high-riskareas in southern China

Objective On 29 October 2000 poliomyelitis was officially declared to have been eradicated from the Western Pacific Region. This article describes the results of surveillance for cases of acute flaccid paralysis (AFP) in Chin a during the final phase of the eradication effort. Methods We conducted hospital-based active surveillance in high-risk areas for poliomyelitis in 5 provinces of southern China (Sichuan, Yunnan, Guizho u, Guangxi and Jiangxi) between 1995 and 1997 to determine the adequacy of reporting and laboratory diagnosis of cases of AFP. Findings A total of 1069 AFP cases occurring since 1993 were identified in 311 hospital visits. Less than 50% of AFP cases occurring in 1993 and 1994 had been reported by AFP surveillance, and laboratory diagnosis had been ca rried out on only a small proportion of these. However, improved cooperatio n between hospital sectors increased the rate of case reporting and laborat ory diagnosis to 85% and 78%, respectively, in 1997. Despite this overall i mprovement, these two indicators were approximately 10-20% lower in Yunnan Province. Epidemiological analysis revealed that cases of clinical poliomye litis accounted for as much as one-third of all AFP in 1993 and that some o f these cases were clustered. Clusters were rarely observed after 1994. Act ive surveillance in the China-Myanmar border areas of Yunnan over 1995-96 d etected 9 cross-border cases of clinical poliomyelitis, including 2 of wild poliomyelitis. Import of poliomyelitis was thus considered to have occurre d frequently until 1996 in this border area of Yunnan. These data were impo rtant for the outbreak response immunization carried out in 1996 in the bor der prefectures of Yunnan. Conclusion Our investigation confirmed a high level of AFP surveillance in poliomyelitis high-risk areas of the five provinces and provided valuable i nformation on the interruption of wild poliovirus circulation in southern C hina that will be of use to countries in other regions that have yet to era dicate poliomyelitis.