326 | Veterinary Record | March 28, 2015 Surveillance Surveillance Surveillance Bovine TB infection status in cattle in Great Britain in 2013 BOVINE TB This report, provided by the APHA, summarises the infection status of bovine TB in cattle in Great Britain from January 1 to December 31, 2013 and describes some of the temporal trends observed over a longer period. It updates the previous annual summary for 2012, also published in Veterinary Record (VR, June 14, 2014, vol 174, pp 600-604). THE aim of publishing this summary of the annual GB bovine TB surveillance reports is to provide a concise description of the epidemiology of TB in cattle in GB on an annual basis and to put the surveillance data into context. The incidence of bovine TB and other related statistics are measured using surveillance data collected by the APHA through its IT system known as SAM. Further description and analysis of the data is available in the full reports, which are publicly available on the UK government website (AHVLA 2014a, b, c). The frequency and geographic distribution of bovine TB in England and Wales have been increasing since the mid-1980s (Fig 1 in Defra 2011). Control measures in cattle include routine testing and slaughterhouse surveillance, premovement testing, movement restriction of infected herds and rapid slaughter of infected animals. Controlling the disease in wildlife reservoirs is a key factor towards eradication in GB; the tools to achieve this include promoting good biosecurity; supporting badger vaccination in Wales and England; and industry-led, licensed badger culling pilots in two high- incidence areas of England. New incidents A new incident (or breakdown) refers to bovine TB being disclosed in an unrestricted cattle herd within the reporting period; in this case, 2013. Herds are described by their Official Tuberculosis Free (OTF) status, which can be OTF-withdrawn (OTF- W), OTF-suspended (OTF-S) or, if free from restrictions, OTF. A new OTF-W incident refers to the detection of bovine TB in an OTF herd in the reporting period (ie, calendar year 2013) of at least one test reactor or inconclusive reactor with postmortem evidence of Mycobacterium bovis infection (judged by the presence of visible lesions typical of TB and/or identification of M bovis in culture), or at least one slaughterhouse case that yielded M bovis on culture. An OTF-S incident refers to a bovine TB incident in a herd where at least one test reactor or two IRs have been identified but evidence of infection could not be confirmed through postmortem examination or laboratory culture of tissue samples. Some herds in Wales that would have been classified as OTF-S (because there was no supplementary postmortem evidence of infection) are classified as OTF-W2 because they are considered to have a high probability of infection according to defined epidemiological criteria. These are an additional cohort to the traditional OTF-W incidents described above and are managed in the same way as OTF-W incidents but have no postmortem evidence of infection. OTF-W2 incidents are classified as OTF-S in this analysis to retain consistency between all jurisdictions of GB; however, in 2013, 54 per cent of incidents in Wales classified as OTF-S in this report were actually classified and managed as OTF-W2 in the field. For disease surveillance and control purposes, three bovine TB risk areas were formally established in England on January 1, 2013, replacing the previous division by one-, two-, three- or four-yearly tested interval parishes; cattle herds in the high risk area (HRA) and Edge area are tested annually and those in low risk areas (LRAs) are tested every four years. The HRA includes counties where bovine TB is considered endemic in cattle herds and badgers. The Edge includes areas where bovine TB incidence is increasing and where new endemic bovine TB is projected to occur in the next 10 years. The distribution of incidents disclosed in 2013 in England has been described according to these bovine TB risk areas (Fig 1). All herds in Wales have been tested annually since 2010, following the testing J. M. Broughan, K. A. Harris, A. Brouwer, S. H. Downs, A. V. Goodchild, Department of Epidemiological Sciences, P. A. Upton, Data Systems Workgroup, N. H. Smith, Bacteriology, APHA, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB e-mail: jennifer.broughan@apha.gsi.gov.uk FIG 1: New incidents of bovine TB in 2013, with the risk areas of England overlaid New OTF-S breakdowns (>1 reactor) New OTF-S breakdowns (0-1 reactor) New OTF-W breakdowns High risk area Edge area Low risk area