Prevalence, incidence, signs and treatment of clinical listeriosis in dairy cattle in England

The prevalence, incidence and clinical signs of listeriosis in dairy cattle in England were investigated by means of a postal questionnaire survey of 1500 dairy farmers. The response rate was 64.1 per cent. overall the farm p revalence of listeriosis was 11.7 per cent, 9.3 per cent for milking cows, 5.0 per cent for replacement heifers and 1.4 per cent for dairy calves. The within-herd incidence rate per thousand animal-years was 51.4 for all case s, 39.7 for milking cows, 86.6 for replacement heifers and 73.7 for dairy c alves. Most cases of clinical listeriosis were reported between December an d May, and the most common signs were silage eye, followed by nervous signs . The results of the questionnaire were validated internally by re-estimati ng the farm prevalence by including only those cases diagnosed by a veterin arian or veterinary investigation centre; the prevalence did not change sig nificantly. The proportion of cases which were culled or died of encephalit ic listeriosis was compared with the proportion diagnosed during statutory BSE reporting. The fact that the two proportions were similar provided exte rnal validation for the results of the questionnaire.