The association of cattle husbandry practices, environmental factors and farmer characteristics with the occurence of chronic bovine tuberculosis in dairy herds in the Republic of Ireland

Abstract

A matched case-control study was undertaken to provide information on the role of farm management practices, environmental factors and farmer characteristics in the epidemiology of bovine tuberculosis. Eighty dairy herds with chronic tuberculosis were compared with the same number of herds which had been free of the disease for many years. A standardized questionnaire was used to obtain information from the farmers. the study was conducted from August to October 1990, in Counties Cork and Kilkenny, Republic of Ireland. Factors which were identified as possibly contributing to recurrent outbreaks of tuberculosis outbreaks included nutritional factors, cattle purchases (especially bulls), the presence of badgers, and the spreading of slurry. Overall, the findings suggested that intensively managed dairy herds were at greater risk of bovine tuberculosis outbreaks than were other herds. The study did not support some of the hypotheses which traditionally have been put forward as contributing to tuberculosis outbreaks. These included contact with neigboring cattle owing to movements to and from fragments or poor boundary fencing, presence of sub-standard cattle housing, movement of equipment or vehicles onto farms, and exposure to water supplies from rivers or streams. In the light of these findings, and in view of the lack of evidence in the scientific literature to support these hypotheses, we suggest that a general re-evaluation of their role in chronic tuberculosis is needed.