Patterns of foot-and-mouth disease virus distribution in Africa: the role of livestock and wildlife in virus emergence
Foot-and-mouth disease (FMD) is one of the most highly contagious diseases of animals. The disease is distributed on three continents (Asia, Africa and South America) where it disrupts the food security of people who depend on livestock and animal products. Substantial economic losses are associated with controlling FMD outbreaks in many countries. For example, during the epidemic in the UK in 2001, losses to agriculture were estimated to be £3.1 billion, with similar losses arising from negative impacts on tourism. Over 4 million animals were slaughtered as part of FMD control measures and a further 2 million were slaughtered due to welfare issues associated with animal movement bans. FMD also has a devastating impact on rural livelihoods and livestock trade opportunities in developing countries where it is endemic. In Africa, historic patterns of FMD virus (FMDV) emergence are likely to have been shaped by the introduction and subsequent eradication of rinderpest. However, important questions remain about contemporary drivers of disease distribution. In particular, the relative contribution of wildlife as sources of infection for livestock and factors affecting the potential for cross-species transmission, and mechanisms of viral maintenance in endemic regions are poorly understood. These issues encompass a complex suite of interacting social, ecological and economic factors that act as drivers of change in patterns of land-use, livestock movements, international trade, and conservation of wildlife-protected areas. Understanding patterns of FMDV infection at the livestock-wildlife interface is of particular importance for designing and developing appropriate disease control strategies in sub-Saharan Africa, and of increasing interest as momentum grows for global control of FMD within the framework of the Progressive Control Pathway (PCP-FMD). This chapter reviews the historical distribution and emergence of FMDV in Africa, and factors that govern the current circulation and maintenance of FMDV in sub-Saharan Africa.