Surveillance for polio eradication in the People's Republic of China.

A case-based virus surveillance system for wild poliovirus in China was developed. By 1993, all 30 provincial immunization units and, by 1994, all 29 provincial laboratories were sending computerized data to the national level. In 1993, a county-level, computerized map was operationalized that permitted visual monitoring of the progress of the polio eradication program every month by county. In 1993, wild poliovirus type 1 was detected in 8 provinces. Wild poliovirus mainly caused clusters of polio cases identified by a surveillance system that detected primarily clinical polio in children <5 years old (1 stool sample was collected on approximately 50% of reported cases). By 1995, the surveillance system had reached certification-like levels (80% of acute flaccid paralysis [AFP] patients with 2 stool specimens and AFP case rate of 1/100,000 children <15 years old). No indigenous wild poliovirus was detected in 1995. This general case-based model can be applied to measles and other important diseases, and may then lead to a more rapid decrease in adverse health outcomes.