During the period from 1993 to 1997, 126 poliovirus positive cases from samples of 1.098 acute flaccid paralysis patients of all provinces in the Northern region and 5 others in the Central region of Viet Nam have been identified. Among them 97 cases were caused by poliovirus type 1, 5 by type 2, 10 by type 3, 11 were identified as a multitype infection and 3 cases were the combination of poliovirus and enteroviruses. The antigenic properties of the poliovirus strains isolated have been studied using monoclonal antibody and polymerase chain reaction. The results showed that, 53 strains of poliovirus type 1 were identified as the wild-type virus, the rest were of Sabin-type virus. The wild poliovirus strains were then classified in to 2 groups by polymerase chain reaction - restriction fragment length polymorphism and sequencing methods. No case of wild type virus was isolated since 1994.
Poliomyelitis ; Polioviruses ; Paralysis

During the period from 1999 to 2000, 12 poliovirus isolates were obtained from acute flaccid paralysis (AFP) cases and 2 from healthy children who have been vaccineated with Sabin's oral polio vaccine. These isolated have been examined by PCR-RFLP. The results showed that the isolates were genetically identical to the regional Sabin's poliovirus strains
Poliomyelitis ; Poliovirus Vaccine, Oral ; Polioviruses ; Paralysis ; Child