Academic journal article Bulletin of the World Health Organization

Active Surveillance for Acute Flaccid Paralysis in Poliomyelitis High-Risk Areas in Southern China

Academic journal article Bulletin of the World Health Organization

Active Surveillance for Acute Flaccid Paralysis in Poliomyelitis High-Risk Areas in Southern China

Article excerpt

Voir page 109 le resume en francais. En la pagina 109 figura un resumen en espanol.

Introduction

In 1988, WHO launched a global initiative to eradicate poliomyelitis by the year 2000 (1). In 1994, the Pan American Health Organization (PAHO) achieved interruption of wild poliovirus transmission in the Americas, with the last case of indigenous poliomyelitis being detected in Peru in 1991 (2). PAHO's success indicates that poliomyelitis eradication is a realistic goal and has provided encouragement to other countries to develop eradication activities (3). Efforts towards this end have successfully brought about the eradication of poliomyelitis also in the Western Pacific Region, as announced on 29 October 2000 (4-6). The present article provides an account of surveillance activities in high-risk areas of southern China during the final stages of the eradication effort. As such, experiences gained will be of interest to countries in other regions where poliomyelitis is yet to be eradicated.

In China, the most recent poliomyelitis outbreaks began in 1989 in the eastern provinces of Shandong, Henan and Anhui. More than 10 000 cases had been reported nationwide by the end of 1991 (7). During this period, a number of provinces conducted oral poliovirus vaccine (OPV) supplemental immunization programmes based on their own policies. In December 1993, coordinated national immunization days (NIDs), consisting of two rounds of immunization sessions, began targeting about 80 million children. After 1996 this programme was continued on a smaller scale as subnational immunization days (SNIDs) (4, 5). As a result, poliomyelitis outbreaks declined in frequency, and the last 6 indigenous cases were detected in 1994 (8). Four cases of wild virus infections detected in Yunnan Province in 1995 and 1996 were imported from a poliomyelitis-endemic country, (4, 5). Although these results indicated that China was achieving interruption of wild poliovirus circulation, reliable surveillance for cases of acute flaccid paralysis (AFP) had to be carried for proper evaluation.

In the five southern provinces of Sichuan, Yunnan, Guizhou, Guangxi and Jiangxi, most areas are economically underdeveloped and there is substantial variability in the quality of public health services. Unlike the northern provinces of China, endemic wild poliomyelitis cases were detected in these southern provinces until relatively recently: up to 1992 in Sichuan, Guangxi and Jiangxi and up to 1993 in Yunnan and Guizhou (9). Yunnan and Guangxi also shared a border with polio-endemic countries. Furthermore, development of AFP surveillance was delayed until around 1994. We investigated the adequacy of case reporting and laboratory diagnosis of AFP cases in hospitals throughout these five provinces in view of their importance for poliomyelitis eradication in China. This active surveillance thus became a unique opportunity to evaluate the development and reliability of AFP surveillance that was fully dependent on reporting from lower levels.

Methods

AFP surveillance

The Chinese Ministry of Health has specified 14 paralytic conditions occurring among children under 15 years of age, including poliomyelitis and other paralytic illnesses such as Guillain-Barre syndrome and non-poliovirus myelitis, as disorders to be reported to the AFP surveillance. All county epidemic prevention stations (EPS) were requested to investigate AFP cases and collect stool specimens from these cases within 24-48 h of notification. The main guidelines for AFP surveillance were as follows: AFP reporting rate of [is greater than] 1 per 100 000 children aged [is less than] 15 years; [is greater than] 80% of cases investigated within 24-48 h of notification; [is greater than] 80% of cases with two stool samples taken within 14 days of the onset of paralysis, i.e. adequate specimens (9).

The patients' demographic and clinical data, together with two stool samples, were forwarded to the provincial EPS. …

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