Tuberculosis in cattle: new perspectives.

Abstract

Today, the risk to human health is at a low level in most developed countries. This has shifted the emphasis to the trading implications of the disease in cattle and has led to a deterioration in the appreciation of risk by all except those who are directly affected by the occurrence of tuberculosis in their herd. The success of earlier national bovine tuberculosis eradication programmes was achieved at a time when herds were smaller, the intensity and demands of production lower, and before the emergence of a significant wildlife reservoir of Mycobacterium bovis. There are other impediments to eradication, however, not least of which are the limitations of the tuberculin test and the failure adequately to address other environmental sources of M. bovis. Provided the security of the herd is established, then the use of the tuberculin test can generally be relied upon to detect infection in exposed herds. The strategic use of cytokine assays can provide a further means of identifying infected cattle and ensuring their early removal. However, if infection has been introduced into the herd by means other than an infected bovine animal, then the security offered by the programme of tuberculin testing, in the absence of other control measures, is of limited value.Geographical information and data management systems can now be used to identify those areas where tuberculosis is currently being actively disseminated and where additional resources can most usefully be deployed. A clearer understanding of the mode of herd to herd transmission of M. bovis can thus be achieved and this can lead to a broader approach to the control and eradication of this zoonotic disease.