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Bovine TB infection status in Great Britain in 2016
  1. K. A. Harris,
  2. A. Brouwer,
  3. P. A. Upton,
  4. M. P. Romero Garcia,
  5. J. C. Gibbens and
  6. J. Dale
  1. Department of Epidemiological Sciences, APHA, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB
  2. Epidemiology Assessment Centre, APHA, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB
  3. Bacteriology, APHA, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB
  1. e-mail: kate.harris{at}apha.gsi.gov.uk

Statistics from Altmetric.com

Number of new incidents

Bovine TB was detected in 4495 of the 76,059 live herds in Great Britain in 2016. England had the highest proportion of new incidents, affecting 7.3 per cent of all herds. Wales was slightly lower with 6.1 per cent of herds with new bovine TB incidents detected. In Scotland only 0.3 per cent of herds experienced a new incident in 2016 (36/13,273). The number of new TB incidents decreased between 2015 and 2016 in the high risk area (HRA) and low risk area (LRA) of England, and in the high and low TB areas of Wales, Scotland and GB as a whole. An increase was observed in the Edge area of England (Table 1).

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Table 1:

Key bovine TB occurrence and other epidemiological parameters, by country, in 2016

Between 1986 and 2000 the number of new TB incidents detected in GB per quarter doubled in size approximately every five years. This was followed by a substantial increase in cases after the 2001 foot-and-mouth disease (FMD) epidemic, during which TB surveillance was suspended. Thereafter the epidemic slowed, with a doubling time of 11.4 years from 2003 to 2010, followed by a slight downward trend from 2011 onwards with a halving time (time taken for the number of TB incidents to halve) of 38.9 years for total TB incidents, and 60.2 years for incidents in which Officially TB Free (OTF) status was withdrawn (OTF-W) (Fig 1). However, the number of active herds has decreased and there have been important changes in TB testing policy over time. So the improving trend in recent years (albeit with a much higher number of infected herds than before FMD 2001) needs to be viewed with caution.

Fig 1: Quarterly number of total and OTF-W new TB incidents detected in GB between January 2001 and December 2016. The OTF-W breakdowns include OTF-W2 incidents in Wales. OTF-W2 herd have their OTF status withdrawn for epidemiological reasons (not on the basis of postmortem examination or culture); such cases were previously classified in the GB report as OTF-S. The solid line shows the actual trend; the slope shows the doubling (or halving) time (the time taken for TB incidents to double or halve in number) for January 2001 to December 2016. R-squared (R2) values (calculated in Stata7) are based on actual monthly figures. The R2 value shows the proportion of variation in the data explained by the fitted regression line; the low values imply an erratic trend

Key points

  • There are substantial differences in the behaviour of the bovine TB epidemic at country, risk area and county level

  • In Great …

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