Molecular genetics of foot-and-mouth disease and the role of small ruminants in its epidemiology in Uganda

Abstract

Foot-and-mouth disease (FMD), the focus of this study, is one of the most important livestock diseases that undermine livestock production and marketing in the world. In Uganda, control of FMD has mainly been through extensive ring vaccinations, restrictions to trade in and movement of livestock and livestock products in affected areas and zoo sanitary measures. Despite these efforts, the number and frequency of outbreaks continues to rise annually. The goal of this study was therefore to generate knowledge that contributes to the design of a knowledge-based disease control programme in Uganda. In particular, the study investigated; the importance of goats and sheep in the epidemiology of FMD in Uganda as well as determination of patterns of genetic variation within FMD viruses in East Africa. Main findings show that goats and sheep are affected by FMD, despite the usual absence of symptoms. In addition, the study has brought to light the fact that husbandry practices involving less movement and mixing of animals may offer some level of protection even within high risk areas. SAT 2 FMD viruses recovered from animals slaughtered three months after restrictions to livestock movement as a result of FMD outbreak had been lifted in Kiboga district closely resemble those isolated from neighboring countries in the region. These results indicate that the epidemiology of FMD in Uganda is more complicated than previously thought. Implications of these results for disease control have been discussed. Evolutionary relationships of the four topotypes within the most prevalent serotype (O) in East Africa have been established. Possible incursions into Uganda and Kenya, of topotypes EA-3 and EA-4 from Ethiopia, Eriteria and Sudan have been suggested. Lastly, recombination within serotype O has been detected as one of the forces possibly driving evolution in the non structural regions of the genome.