CURRENT RESEARCH ON AN ALTERNATIVE FOOTROT CONTROL STRATEGY

The expression of footrot results from an interaction between a specif ic transmitting agent, Dichelobacter nodosus, other micro-organisms, t he innate and acquired resistance of the host, and the environment in which the sheep are kept. The economic impact of footrot is determined by the prevalence of severe infections and the duration of these infe ctions. For a high risk environment the annual cost of footrot per 100 0 sheep may range from $14,000 to almost 0, depending on the virulence of the transmitting agent. It is unlikely that National Eradication p rogrammes will be successful, and most conventional control options ar e expensive and require re-current inputs. Alternative and long-term c ontrol strategies therefore warrant investigation. One form of long-te rm control would be to adapt the genotype of the host in such a way th at virulent and intermediate footrot is expressed to the same extent a s benign footrot. The economic impact of infection with virulent isola tes of D. nodosus will be reduced that of benign isolates (i.e. benign footrot).