CONTAGIOUS ECTHYMA IN THE LIVE SHEEP EXPORT INDUSTRY

Objective To investigate control options for contagious ecthyma (scabb y mouth) in Australian sheep exported live to the Middle East. Design Prevalence, vaccination and modelling studies. Procedure One hundred a nd forty weaner sheep (less than 1 year old) on each of 106 farms in W estern Australia (WA) and 18 farm groups of adult wethers received at a WA commercial feedlot were examined for lesions of scabby mouth. She ep on a total of 26 farms in 3 States were divided into treatment and control groups for the vaccination study. A simple deterministic compa rtmental model was developed to establish which parameters had the gre ater effect on disease prevalence. Results The proportion of farms wit h evidence of scabby mouth in weaner sheep was 23.6% and, on those far ms with the disease, the overall prevalence was 6.1%. At the feedlot, 4 out of 18 farm groups had 5 or more sheep with lesions on arrival. T he overall prevalence in the 4 diseased groups was 5.2%. Sheep vaccina ted on farm before trucking to the feedlot had a lower prevalence of s cabby mouth at the end of simulated shipping than controls. The main d eterminant of scabby mouth prevalence was the proportion of sheep immu ne to the disease. Conclusion A program of vaccination for scabby mout h will reduce the prevalence of disease during live export. However, u sing current technology it is not possible to deliver shipments of she ep to the Middle East that are guaranteed completely free of scabby mo uth.