The Institute for Medical Research, Malaysia, was designated the National Reference Laboratory for Poliomyelitis Eradication (NRLPE) in 1992. Since then, our Polio Laboratory has collaborated actively with the Disease Control Division, Ministry of Health (MOH), Malaysia and WHO towards achieving polio eradication. Since 1992, the NRLPE has investigated 1,063 stool specimens from 641 acute flaccidparalysis (AFP) cases. One hundred and one enteroviruses were isolated from these specimens. Positive cell cultures were confirmed by microneutralization assay using standard WHO antisera. All enterovirus isolates were sent to the Victorian Infectious Disease Reference Laboratory in Melbourne, Australia, for further identification and poliovirus intratypic differentiation. Thirty-one out of these 101 virus isolates (30%) were polioviruses (PV) and the remaining 70 (70%) were non-polio enteroviruses (NPEV) which included coxsackie B viruses, echoviruses and enterovirus 71. Three of the poliovirus isolates were wild-type polioviruses isolated in 1992 which were the last wild-type polioviruses isolated in Malaysia. The rest were vaccine-related Sabin-like strains. Monthly reports of the virological investigation of AFP cases are sent to WHO and to the MOH, AFP control committee. The NRLPE continues to play an integral role in AFP surveillance and is committed to the WHO's goal of global polio eradication by the year 2005.
Stool samples from healthy children mainly of the low income group aged 0 to 7 years of age from five Maternal and Child Health Centres in Kuala Lumpur were obtained for isolation of enteroviruses. The specimens were collected before and after the mass vaccination given in the face of polio type 1 epidemic which started in October, 1971. The prevelance rate of enteroviruses was 11.9% (3.0% polioviruses, 8.9% non-polio enteroviruses) before the vaccination and essentially the same after. Coxsackie A viruses predominated over the other enteroviruses in the pre- and post-vaccination phases. The highest isolation rate of enteroviruses was observed in children 0 to 2 years age. No significant differences in distribution by sex, race and month were noted. A sharp fall in the prevalence rates of total enteroviruses and polioviruses was noted shortly after the mass vaccination campaign However, the rates reverted to the pre-vaccination state during the next successive years.