Mokola virus, one of the six genotypes within the Lyssavirus genus of the Rhabdoviridae family, is believed to be exclusive to the African continent, where infections in various mammal species have been reported. After an isolation of Mokola virus at Umhlanga on the east coast of South Africa in 1970, the virus was not reported in South Africa until its reappearance in 1995. Since then a total of six new isolates of the virus were made, three from the East London region in 1995 and 1996, two near Pinetown in 1997 and a further isolate in a residential suburb of the city of Pietermaritzburg, in 1998. These isolation sites are respectively about 500 km (East London region) and 23 to 60 km from the site of the 1970 isolation Phylogenetically the three isolates from the East London area were similar and could be distinguished from the four KwaZulu-Natal isolates, which formed a defined group of their own. The viruses comprising these two clusters were also found to be distant from another southern African isolate, made in 1982 in Zimbabwe, Mokola virus isolates thus conforms to a pattern of virus evolution strongly influenced by geographical determinants. In comparison to Rabies virus, of which at least two different biotypes are known and a vast array of different wildlife species contribute to its complex epidemiology on the sub-continent, Mokola viruses have only been isolated form one species, i.e. domestic cats, in South Africa. Nevertheless, the heterogeneity among the Mokola virus isolates is far greater than the degree of variation among the Rabies virus populations of the region.

Rabies enzootics in southern Africa are associated with two genetically distinct groups of viruses, thought to be adapted to two different sets of host species. The virus groups are referred to as the canid biotype (infecting carnivores of the family Canidae) and the viverrid biotype (infecting carnivores of the subfamily Viverrinae). Cross- or spillover infections of one biotype into the host range of the other are thought to occur from time to time. However, very little is known about this phenomenon and its role in the epidemiology of rabies in southern Africa. We have investigated spillover by monoclonal antibody and nucleic acid sequence analysis of a wide range of virus isolates. Although the inverse had been documented, this report constitutes the first evidence of spillover of canid biotype viruses into viverrid hosts. Our genetic analysis was focused specifically on the G-L intergenic region of the virus genome, thought to be a remnant or pseudogene and it was indicated that, with respect to this region of the genome, spillover does not influence the phylogeny of virus isolates.

The dichotomy of retention versus promotion in education is persistent. It is a high stake decision teachers, administrators, and policymakers have to make. This article critically reviewed the die-hard retention factors and looked at alternative ways to deal with them. It emphasizes that the approach to repeating grades cannot be taken frivolously. Teachers, administrators, and policy makers' decisions will not only have life-long effects for the individuals upon whom they are placed, but they will undoubtedly affect the future societies as a whole. This article suggested that both teachers and administrators have the vital and deciding power to elect which approach to take, contextualizing curricula and professional development training sensitive to grade retention issues. Educational administrators and teachers must have the insight to recognize the failures and the courage to accept new ways to deal with old problems.