Retrospective genetic analysis of SAT-1 type foot-and-mouth disease outbreaks in West Africa (1975-1981).

The complete 1D genome region encoding the immunogenic and phylogenetically informative VP1 gene was genetically characterized for 23 South African Territories (SAT)-1 viruses causing foot-and-mouth (FMD) disease outbreaks in the West African region between 1975 and 1981. The results indicate that two independent outbreaks occurred, the first involved two West African countries, namely Niger and Nigeria, whilst the second affected Nigeria alone. In the former epizootic, virus circulation spanned a period of 2 years, whilst in the latter virus was recovered from the field over a 3 year period. Comparison of the West African viruses with SAT-1 viruses from other regions on the continent revealed that the two West African lineages identified in this study are regionally distinct. Furthermore, variation in VP1 gene length was identified in SAT-1 viruses for the first time, further emphasizing the uniqueness of these pathogens in West Africa. This first retrospective analysis in which the molecular epidemiology of SAT-1 viruses in West Africa is reported, provides a useful measure of the regional variation of these viruses and is an essential first step in the establishment of a West African sequence database that will be a useful reference for future outbreak eventualities.