In Shandong Province, China, programmes were initiated in 1991 for mass immunization against poliomyelitis and for the immediate reporting of acute flaccid paralysis (AFP). The incidence of non-poliomyelitis AFP was found to be 0.46-0.61 cases per 100,000 children per annum. It appeared that illness resembling the Guillain-Barré syndrome was underreported. The incidence of such illness peaked among children aged 2-3 years. Although laboratory investigations have improved, in 1992 they were still inadequate in nearly a third of confirmed poliomyelitis cases. As the prevalence of wild poliovirus declines in China, reliable laboratory support needs to be established and adequately sensitive and specific AFP surveillance be developed if poliomyelitis is to be eradicated.

In five years from 1988 to 1992, 51 polioviruses were isolated from patients with acute flaccid paralysis in Shandong province in China. Of the 51 poliovirus isolates, 17 were type 1, 18 type 2 and 16 type 3. Twelve type 1 viruses isolated during the period from 1988 to 1990 were shown to be wild strains by serology and the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods. These wild strains were classified into three groups by PCR-RFLP. The other type 1 isolates were Sabin-like strains. No wild strain was isolated in 1991 or 1992. All isolates of types 2 and 3 during the five years were Sabin-like strains. These data suggest that wild strains of polioviruses will soon be eradicated in Shandong province.

Widespread outbreaks of paralytic poliomyelitis occurred in Shandong province, China, starting from 1988. In 1989, 484 cases were recorded, which was the peak during the past 4 years. Although emergency immunization with trivalent oral poliovirus vaccine (OPV) was carried out in selected counties in 1989 and 1990, control of the outbreak was not satisfactory. OPV mass immunization campaigns were introduced to cover the whole province in early 1991, and the number of patients with paralytic poliomyelitis decreased to 95. In addition to this new immunization strategy, we began to construct new polio surveillance systems.These were a network for case-negative reporting and an immediate reporting system of acute flaccid paralysis (AFP) . As for the case-negative reporting, presently more than 90% of counties have been reporting presence or absence of new AFP cases. Monitoring of AFP immediate reporting has also shown a gradual improvement in several aspects. These polio surveillance activities are crucial to polio eradication programme management.