Research by DARD’s Veterinary Epidemiology Unit (VEU) about TB

The following research has been carried out by DARD’s Veterinary Epidemiology Unit (VEU) in relation to Bovine Tuberculosis.

TB research carried out by DARD's Veterinary Epidemiology Unit

A comparison of badger activity in two areas of high and low bovine tuberculosis incidence of Northern Ireland

During 2005, a field survey of badger activity was carried out to evaluate differences between two areas with different levels of bovine tuberculosis (annual herd incidences of 16% and 4%) and to assess the awareness of herd keepers in relation to badgers. A random selection of herd keepers was interviewed and their farm land surveyed for the presence of badgers. The survey end point for each farm was the discovery of an active badger sett.

articipation was very high in both areas (>80%). Evidence of badger activity was recorded on a higher proportion of farms in the area with a high tuberculosis herd incidence. However, when the difference in quality of agricultural land within each area was taken into account, a statistically significant association was not demonstrated. This suggests that the quality of agricultural land is a major determinant in the location of active badger setts. Nevertheless, the study did demonstrate the potential for increased exposure of cattle to badgers in the high incidence area.

Herd keepers accurately identified the presence of badger setts on their land (positive predictive value = 97%) but herd keepers reporting the absence of badger setts/activities on their land were found to be less accurate. Overall, the conclusions from this study tend to reflect the findings observed in other studies.

A manuscript only version of this paper is available at the link below:

Alternatively, the final article as published in the journal Veterinary Microbiology is available via Science Direct:

A matched cohort study investigating the risk of Mycobacterium bovis infection in the progeny of infected cows

The aim of this study was to quantify the risk of bovine tuberculosis in the last progeny of cows confirmed with this infection using historical computerised records to perform a retrospective cohort study. The exposed cohort was defined as the last calf of dams that were diagnosed as having bovine tuberculosis during 2002. The progeny were only retained for subsequent analysis if they were born in the nine months preceding slaughter of the dam and if they lived for more than fifteen months. The unexposed cohort comprised of animals born in the same herd within one month of the exposed cohort and was matched one-to-one. The resultant data set contained 1,156 matched cohorts. Forty-two animals from the exposed cohort and 35 from the unexposed cohort had bovine tuberculosis. The relative risk was estimated at 1.2 (95% confidence interval 0.8 – 1.79). It was concluded that progeny of tuberculous dams were not at a significantly increased risk of Mycobacterium bovis infection.
A manuscript only version of this paper is available at the link below:

Alternatively, the final article as published in The Veterinary Journal is available via Science Direct:

BCG vaccination against tuberculosis in European badgers (Meles meles): a review

Tuberculosis (TB) is a significant animal health problem in many parts of the world, and reservoirs of infection in wild animals complicate disease control efforts in farmed livestock, particularly cattle. Badgers (Meles meles) are a significant wildlife reservoir of TB infection for cattle in Great Britain and Ireland. Vaccination of badgers using a Mycobacterium bovis strain bacille Calmette-Guèrin (BCG) vaccine may potentially be a tool in the national TB eradication strategy. Wildlife vaccination has been used successfully for other diseases and in other wildlife species, and may have a role to play in reducing transmission of infection at the wildlife-livestock interface. Research to date has provided evidence that BCG is protective in badgers, and a parenteral badger BCG vaccine has been licensed in the United Kingdom. Further research is required to develop effective strategies for vaccine deployment and to determine the effect of badger vaccination on cattle TB incidence.

A manuscript only version of this paper is available at the link below:

Alternatively, the final article as published in the journal Comparative Immunology, Microbiology and Infectious Diseases is available via Science Direct:

Bovine tuberculosis trends in the UK and the Republic of Ireland, 1995–2010


Abernethy, D.A., Upton, P., Higgins, I., McGrath, G., Goodchild, A.V., Rolfe, S.J., Broughan, J.M., Downs, S.H., Clifton-Hadley, R., Menzies, F.D., de la Rua-Domenech, R., Blissit, M.J., Duignan, A. and More, S.J. (2013).  Bovine tuberculosis trends in the UK and the Republic of Ireland, 1995–2010.  Veterinary Record, 172, 312-326. doi:10.1136/vr.100969

Selected demographic features and trends in bovine tuberculosis (BTB) from 1995 to 2010 are described for the countries of the UK and the Republic of Ireland, using standardised definitions and measures. All countries experienced a reduction in the number of cattle and herds and in the proportion of dairy herds, while average herd size increased. In general, the trends indicate a stable situation of very low BTB prevalence in Scotland and, over most of the period, a rising prevalence in England and Wales. The prevalence in the Republic of Ireland declined while Northern Ireland experienced both a rise and fall. Differences in demography, BTB programme structure and test results were noted, particularly between the island of Ireland and Great Britain. Further investigation of these differences may provide valuable insights into risk factors for BTB and optimisation of existing BTB programmes.

The final article is available via the journal Veterinary Record:

International Vaccination Expert’s Scientific Symposium

DARD hosted an International Vaccination Expert’s Scientific Symposium from 14-16 May 2012 to consider vaccination of wildlife as a means of reducing bovine tuberculosis (BTB) in cattle. Experts in ecology and wildlife vaccination and related science disciplines from around the world attended. DARD anticipates that the symposium outputs will make a valuable contribution to the role of vaccination, across a range of wildlife species (and, in particular the badger) and epidemiological contexts. Ultimately, it will inform decision-making on this subject and address key information gaps to help ensure that taxpayers’ money used to tackle TB will be spent more prudently and effectively.

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