A CASE-CONTROL STUDY ON THE ASSOCIATION OF SELECTED RISK-FACTORS WITHTHE OCCURRENCE OF BOVINE TUBERCULOSIS IN THE REPUBLIC-OF-IRELAND

We did a case-control study on the association between the occurrence of bovine tuberculosis in herds in the East Offaly area and a number o f possible risk factors: herd size, the purchasing of cattle, the herd history, the status of contiguous herds, distance to the nearest badg er sett, and animal factors such as age, breed and animal type. The ch aracteristics of 100 herds that had a confirmed outbreak of tuberculos is at a herd test in 1988 were compared with those from an equal numbe r of herds that passed at least one tuberculin test during that year. The study base consisted of 1379 herds mainly from the eastern part of County Offaly. The data were analysed at both herd and animal levels. Factors that were associated with an increased risk of tuberculosis b reakdowns at the herd level were (i) the total number of animals in th e herd and (ii) the restriction of a contiguous herd for tuberculosis within a period of 6 months prior to or following the herd under study . A number of factors were associated with an animal having an increas ed risk of failing a tuberculin test. After adjusting for all other va riables in the model, cows, heifers and bullocks were 10.3, 14.8 and 8 .0 times, respectively, more likely to fail a tuberculin test than cal ves. Cattle that had been purchased since the previous herd test were less likely to Fail a tuberculin test compared with cattle that had be en present at the time of the preceding herd test.