The molecular epidemiology of type 1 poliovirus in Central African Republic.

An increase in the incidence of acute flaccid paralysis cases associated with wild-type 1 poliovirus occurred in children in the city of Bangui, Central African Republic (CAR), in 1993 and 1994. Genetic relationships of 33 isolates were analysed by restriction fragment length polymorphism and by sequencing the VP1/2A junction region (150 nucleotides) of the viral genome. Two distinct genotypes, A and B, were co-circulating in 1993, while in 1994 only a third genotype, C, was observed. Comparison of the sequences found, with those of the sequences from isolates from neighbouring and other endemic countries revealed that genotype A isolates were related to strains from Egypt (90.7% identity), genotype B isolates to strains from Kenya (96.7% identity), Sudan and Egypt, and genotype C isolates to strains from various countries in western and southern Africa (89.0% identity). Genotypic diversity and genetic linkage with strains from neighbouring countries indicate intense poliovirus circulation and transmission that does not respect national borders. Therefore, eradication of poliomyelitis from CAR can only be achieved by a coordinated multinational strategy that stops poliovirus circulation in the whole of Africa.