Research and analysis

Yorkshire and Humberside (Low Risk Area) year end report 2023

Updated 24 October 2024

Applies to England

Introduction

The Low Risk Area (LRA) was established in 2013, along with the Edge and High Risk Areas of England. In 2014 the 3 bovine tuberculosis (TB) risk areas were incorporated into the UK Government’s strategy to achieve Officially TB-Free (OTF) status for England by 2038. A key action was to recognise the different levels of TB in different parts of the country and to adjust the approaches to TB surveillance and control in each risk area accordingly. Overall, the LRA has a very low and stable incidence of TB-infected herds. The current strategy for the LRA seeks to mitigate the risk of TB incursions via cattle movements and rapidly contain and eradicate any foci of infection through:

• mandatory pre- and post- movement testing of cattle entering the LRA from higher risk areas of the UK
• more sensitive testing of infected herds
• temporarily enhanced TB surveillance (radial and hotspot testing) in the vicinity of herds experiencing lesion and/or Polymerase Chain Reaction (PCR) test (or culture)-positive incidents of TB

The aim of this combined approach is to preserve the favourable disease status of this area so that its counties can be declared OTF as soon as possible.

This report describes the frequency and geographical distribution of TB in 2023 in cattle herds in Yorkshire and Humberside, which is part of the LRA. In 2023, 27% of all new TB incidents in the LRA were detected in Yorkshire and Humberside.

TB in cattle and other mammals is primarily caused by infection with the bacterium Mycobacterium bovis (M. bovis) and the disease is subsequently referred to as ‘TB’ in this report. Although other sources may refer to TB ‘breakdowns’, this report will use the term ‘incidents’ throughout.

This report is intended for those involved in the control of TB, both locally and nationally. This includes, but is not limited to:

• cattle farmers
• government and private veterinarians
• policy makers
• the scientific community

Details of the data handling methodology used in this report, a glossary of terms, and the TB control measures adopted in the LRA, can be found in the explanatory supplement for the annual reports 2023.

Types of TB incident

Unless otherwise specified, this report includes all new TB incidents detected during the reporting period, 1 January to 31 December 2023. This includes both ‘Officially Tuberculosis-Free Status Withdrawn’ (OTF-W) and ‘Officially Tuberculosis-Free Status Suspended’ (OTF-S) incidents.

OTF-W incidents are those involving at least one skin test reactor (an animal positive to the Single Intradermal Comparative Cervical Tuberculin [SICCT] test) with either:

• typical lesions of TB identified at post-mortem (PM) meat inspection
• and at least one animal with M. bovis-positive PCR test or bacteriological culture results in tissue samples collected from carcasses during the PM inspection

OTF-S incidents are triggered by reactors to the skin test, but without subsequent detection of TB lesions or positive PCR test (or culture) results in any of those animals.

Cattle industry

In 2023 over 70% of the cattle in the Yorkshire and Humberside region were in North Yorkshire. The number of cattle in this region remained similar to 2021 and 2022, however the number of active herds fell by 4% compared to 2021 and 5% compared to 2022 for those respective years. Small holdings with fewer than 50 animals were the most common herd structure across all counties in the region. In all the counties, beef animals predominated, ranging from 64% to 83% of the total cattle population, whereas dairy animals accounted for 13% to 32% as shown in Appendix 1.

There were 4 TB approved livestock markets operating across the region in 2023, all in North Yorkshire. There were 27 Licensed Finishing Units (LFUs) across Yorkshire and Humberside: 21 in North Yorkshire, 5 in South Yorkshire, and one in Humberside. There was one slaughterhouse (SLH) in North Yorkshire contracted by Animal and Plant Health Agency (APHA) in 2023 to process cattle removed from farms for TB control reasons.

The number of cattle markets in operation in 2023 is captured and maintained centrally by the APHA TB Customer Service Centre. Where possible, this data is then subject to further validation by APHA veterinarians subject to their best knowledge of the local area. Some small discrepancies may therefore exist where changes to markets were not captured in time for this report.

New TB incidents

A total of 36 new TB incidents were disclosed across the Yorkshire and Humberside region during 2023 (14 OTF-W and 22 OTF-S) (Figures 1a and 1b). This was an increase from the 7 OTF-W incidents disclosed during 2022, whereas OTF-S incidents decreased slightly from 24 in 2022.

In North Yorkshire, the number of OTF-W incidents doubled from 4 in 2022 to 8 in 2023, whereas there was a slight decrease in OTF-S incidents from 13 to 11.

In Humberside in 2023, there were 4 OTF-W incidents and one OTF-S incident, compared to only 2 OTF-S incidents in 2022.

In South Yorkshire, there were one OTF-W and 2 OTF-S incidents in 2023. This compared to only 2 OTF-S incidents in 2022.

In West Yorkshire, the number of OTF-W incidents decreased from 3 in 2022 to one in 2023, whereas the number of OTF-S incidents increased slightly from 7 to 8.

North Yorkshire

Year	OTF-W	OTF-S	Total
2014	6	17
2015	11	12
2016	3	8
2017	2	9
2018	6	10
2019	4	12
2020	9	9
2021	4	16
2022	4	13
2023	8	11

Humberside

Year	OTF-W	OTF-S	Total
2014	2	2	4
2015	0	1	1
2016	2	1	3
2017	3	2	5
2018	0	2	2
2019	1	0	1
2020	1	3	4
2021	1	1	2
2022	0	2	2
2023	4	1	5

Figure 1a: Annual number of new TB incidents in Humberside and North Yorkshire, from 2014 to 2023.

Figure 1a description: Stacked bar chart showing the number of new OTF-W and OTF-S incidents detected in North Yorkshire and Humberside between 2014 and 2023. OTF-W incidents are shown in blue and OTF-S incidents are shown in green. In North Yorkshire, there were 8 new OTF-W incidents and 11 new OTF-S incidents in 2023, as described in the main body of text. In 2023, there were 4 new OTF-W incidents and one new OTF-S incident in Humberside.

South Yorkshire

Year	OTF-W	OTF-S	Total
2014	0	1	1
2015	2	3	5
2016	1	7	8
2017	1	3	4
2018	2	1	3
2019	2	8	10
2020	1	2	3
2021	0	0	0
2022	0	2	2
2023	1	2	3

West Yorkshire

Year	OTF-W	OTF-S	Total
2014	0	1	1
2015	2	6	8
2016	0	1	1
2017	0	1	1
2018	0	2	2
2019	0	3	3
2020	3	8	11
2021	2	5	7
2022	3	7	10
2023	1	8	9

Figure 1b: Annual number of new TB incidents in South Yorkshire and West Yorkshire, from 2014 to 2023.

Figure 1b description: Stacked bar chart showing the number of new OTF-W and OTF-S incidents detected in South Yorkshire and West Yorkshire between 2014 and 2023. OTF-W incidents are shown in blue and OTF-S incidents are shown in green. In 2023, there was one new OTF-W incident and 2 new OTF-S incidents in South Yorkshire. In West Yorkshire, there was one new OTF-W incident and 8 new OTF-S incidents in 2023, as described in the main body of text.

The headline cattle TB statistics for each county are summarised in Appendix 2.

Disclosing test type

As shown in Figure 2, of the 36 new TB incidents in the region in 2023, radial surveillance testing detected 10 new incidents. This was followed by routine herd testing, which detected 8, and slaughterhouse surveillance and trace testing which detected 4 each. Post-movement testing and 12-month (post-incident resolution) herd testing detected 3 new incidents each. Check testing, whole herd testing and new herd check testing each triggered one new incident.

Regarding the individual counties, the spread of disclosing test types is largely consistent with 2022, except for a decrease in disclosing routine herd tests in North Yorkshire (from 8 out of a total of 17 incidents to one out of a total of 19 incidents).

Figure 2: Number of new TB incidents (OTF-W and OTF-S) in Yorkshire and Humberside, in 2023 according to the surveillance method that detected them.

Figure 2 description: Bar chart showing which tests detected the new TB incidents in Yorkshire and Humberside in 2023. Most new incidents in North and West Yorkshire were detected by radial testing (4 and 5, respectively). In Humberside, routine herd testing detected most incidents (3), followed by slaughterhouse surveillance (2). In South Yorkshire, radial testing, routine herd testing and trace testing each detected one incident.

The headline cattle TB statistics for Yorkshire and Humberside are summarised in Appendix 2.

Duration of TB incidents

A total of 30 TB incidents were resolved during 2023. Of these, 23 were new TB incidents that started in 2023 and closed before the end of the year. A further 7 incidents were resolved that had started in 2022.

Throughout the Yorkshire and Humberside region in 2023, there were no persistent incidents (under movement restrictions for more than 550 days). All OTF-S incidents that ended in South Yorkshire in 2023 were resolved quickly, in less than 150 days. In Humberside, all incidents that ended in 2023 were resolved within 240 days.

In West Yorkshire, all OTF-S incidents and 2 OTF-W incidents that ended in 2023 resolved within 240 days. One OTF-W incident in West Yorkshire was resolved within 550 days. In North Yorkshire, 12 out of the total 14 incidents resolved within 240 days and the remaining 2 incidents resolved within 550 days.

Thirteen TB incidents were ongoing at the end of 2023 in Yorkshire and Humberside.

Unusual TB incidents

There were no unusual TB incidents in Yorkshire and Humberside in 2023.

TB in other species

There is no statutory routine TB surveillance of non-bovine species, apart from post-mortem examination (PME) of animals slaughtered for human consumption, or carcasses submitted to veterinary laboratories for diagnostic investigations. Targeted TB testing takes place in non-bovine herds under TB movement restrictions due to laboratory-confirmed incidents of M. bovis infection, and in specific herds of camelids, goats and captive deer at an elevated risk of infection.

There were no TB incidents in non-bovine species in Yorkshire and Humberside in 2023.

Recurring TB incidents

Three-year recurrence

In Yorkshire and Humberside, 4 of the 22 (18%) herds with a new OTF-S TB incident in 2023, and 2 of the 14 (14%) with an OTF-W incident, had experienced another TB incident in the previous 3 years, as shown in Figure 3. The overall percentage of new TB incidents that were recurrent in Yorkshire and Humberside in 2023 was 17%. Compared to the other LRA regions, this was the second lowest 3-year recurrence reported. The recurrence percentage in the whole of the LRA was 27%.

Humberside

TB Incident	No history of TB in the last 3 years	History of TB in the last 3 years
OTF-S	1	0
OTF-W	4	0

North Yorkshire

TB Incident	No history of TB in the last 3 years	History of TB in the last 3 years
OTF-S	8	3
OTF-W	5	2

South Yorkshire

TB Incident	No history of TB in the last 3 years	History of TB in the last 3 years
OTF-S	2	0
OTF-W	1	0

West Yorkshire

TB Incident	No history of TB in the last 3 years	History of TB in the last 3 years
OTF-S	7	1
OTF-W	1	0

Figure 3: Number of herds with a TB incident (by OTF-W and OTF-S) in Yorkshire and Humberside in 2023, with and without a history of any TB incident in the previous 3 years. This figure contains one less incident, as in 2023 one herd experienced 2 incidents.

Figure 3 description: Bar chart showing the number of herds a TB incident, by OTF-W and OTF-S, in 2023 with and without a history of TB in the last 3 years. Herds with a history in the last 3 years are shown in green, and those without a history of TB in the last 3 years are shown in blue. In Humberside and South Yorkshire, all OTF-W and OTF-S incidents did not occur in herds with a history of TB in the last 3 years (one OTF-S and 4 OTF-W incidents in Humberside, and 2 OTF-S and one OTF-W incidents in South Yorkshire). In North Yorkshire most incidents occurred in herds with no history of TB in the last 3 years (8 out of 11 OTF-S incidents and 6 out of 8 OTF-W incidents). In West Yorkshire, all but one incident occurred in herds with no history of TB in the last 3 years (7 out of 8 OTF-S and one OTF-W).

Overall recurrence

In 2023, 31% of incidents reported in across the region were in herds with a history of TB at any time, going back beyond the 3-year period mentioned previously (6 out of 22 OTF-S and 5 out of 14 OTF-W), as shown in Figure 4. The recurrence of TB incidents in herds in 2023 was greatest in North Yorkshire (37%), followed by 33% in South Yorkshire, 22% in West Yorkshire, and 20% in Humberside.

Overall recurrence of TB increased slightly compared to 2022 (30%, 8 out of 23 OTF-S and one out of 7 OTF-W). This was due to recurrence increasing in North Yorkshire (31% in 2022 to 37% in 2023). Elsewhere, overall recurrence in Humberside and South Yorkshire fell compared to 2022 (50% to 20% and 33% respectively), and stagnated for West Yorkshire (22% in 2023, 20% in 2022).

Humberside

TB Incident	No history of TB within the herd lifetime	History of TB within the herd lifetime
OTF-S	1	0
OTF-W	3	1

North Yorkshire

TB Incident	No history of TB within the herd lifetime	History of TB within the herd lifetime
OTF-S	7	4
OTF-W	5	3

South Yorkshire

TB Incident	No history of TB within the herd lifetime	History of TB within the herd lifetime
OTF-S	2	0
OTF-W	0	1

West Yorkshire

TB Incident	No history of TB within the herd lifetime	History of TB within the herd lifetime
OTF-S	6	2
OTF-W	1	0

Figure 4: Number of herds with a TB incident (by OTF-W and OTF-S) in Yorkshire and Humberside in 2023, with and without a history of any TB incident. This figure contains one less incident as in 2023, one herd experienced 2 incidents.

Figure 4 description: Bar chart showing the number of herds a TB incident, by OTF-W and OTF-S, in 2023 with and without a history of TB in ever. Herds with a history of TB every are shown in blue, and those without a history of TB at any point in time are shown in green. In Humberside there was one OTF-S incident and 3 out of 4 OTF-W incidents with no history of TB at any point in time. In North Yorkshire, 7 out of 11 OTF-S and 5 out of 8 OTF-W incidents had no history of TB at any point in time. There were 2 OTF-S incidents with no history of TB and one OTF-W incident with a history of TB at any point in time. In West Yorkshire, 6 out of 8 OTF-S incidents and one OTF-W incident had no history of TB at any point in time.

Geographical distribution of TB incidents

New TB incidents in Yorkshire typically occurred in areas of higher cattle density, which is consistent with previous years, except for one case in Humberside and one in South Yorkshire (Figure 5).

Whole Genome Sequencing (WGS) replaced genotyping (spoligotyping and VNTR typing) of M. bovis isolates at APHA in 2021.

In 2023, 8 different WGS clades of M. bovis were detected across Yorkshire and Humberside, compared to only 2 in 2022.

North Yorkshire

In North Yorkshire, there was a cluster of new OTF-W and OTF-S incidents in the centre of this county, caused by different clades of M. bovis. Two of the OTF-W incidents were associated with clade B3-11, which has been detected in this area every year since 2019. This clade of M. bovis is has a large homerange which spans much of Staffordshire, Derbyshire, Cheshire, north-east of Shropshire and parts of Greater Manchester, Leicestershire, Lincolnshire and Nottinghamshire. There was one OTF-W incident with clade B6-62 which has a homerange centred on east of Gloucestershire, north-east of Wiltshire and the southern Edge Area (Oxfordshire, Warwickshire, Berkshire, west of Northamptonshire, north-west of Hampshire and West Buckinghamshire). Incidents associated with clade B6-62 had not been detected in North Yorkshire since 2019, when 2 were disclosed around the same area of the 2023 cluster. A further incident in this cluster yielded clade B6-51, which has a homerange in East Cornwall and West Devon. Two other incidents with clade B3-11 occurred east of the cluster.

There were 2 OTF-S incidents and one OTF-W incident in the north of this county. The latter was caused by infection with clade B4-11, which has a homerange across parts of Avon, Somerset, and Wiltshire and a small area in South Devon.

In the south of this county there was one OTF-W incident disclosed with clade B6-85, which has a homerange across most of Devon and parts of Somerset, Cornwall and Dorset.

In general, OTF-S incidents in North Yorkshire were distributed across the northern, central and western areas of this county. Two of those in the west of this county were located near the boundary of HS27. There were no new TB incidents in the hotspot itself (see below).

Humberside

In Humberside, there were 4 OTF-W incidents disclosed across this county, with no evidence of geographical clustering. Two incidents associated with clade B6-11 (the predominant strain of the bacterium in the West Midlands and adjoining parts of Wales) occurred in the west near the border with North and South Yorkshire but these are not closely genetically related. There were 2 B3-11 incidents in the north and south of this county each in 2023, but these were also not closely genetically related.

South Yorkshire

In South Yorkshire, the one OTF-W incident (clade B3-11) occurred in the centre of this county. This was the first OTF-W incident to occur in South Yorkshire since 2020. The 2020 incident was also associated with clade B3-11 and was situated towards the west of this county. Of the 2 OTF-S incidents, one was located to the east of this county on the border with Humberside and the other in the west of this county.

West Yorkshire

The one OTF-W incident in West Yorkshire occurred in the south of this county, towards the border with South Yorkshire. The WGS clade isolated from this incident was B3-11. OTF-S incidents in West Yorkshire were predominantly located towards the west of this county.

There were 2 OTF-S incidents located around the border with North Yorkshire, one of which was close to the boundary of HS27 and the other was a little further east.

Figure 5: Location of cattle holdings in Yorkshire and Humberside with new TB incidents (OTF-W and OTF-S) in 2023, and cattle holdings with pre-2023 OTF-W incidents still ongoing at the beginning of 2023, overlaid on a cattle density map. Note that ‘OTF-W Introduced 2023’ refers to OTF-W incidents in which cattle movements were the most likely source of infection.

Figure 5 description: A map of Yorkshire and Humberside showing the cattle density, the geographical location of cattle holdings with new TB incidents (OTF-W and OTF-S) in 2023, and OTF-W incidents pre-2023. Dark blue areas represent higher cattle density and light blue represent lower cattle density. New OTF-W incidents detected in 2023 are shown as triangles and colour-coded based on the WGS clade that was detected in the incident. Pink triangles represent clade B3-11, green triangles represent clade B6-11, light blue triangles represent clade B6-51, brown triangles represent clade B6-62, purple triangles represent clade B6-85, dark blue triangles represent B1-11, red triangles represent clade B6-84, and white triangles represent incidents where the WGS clade was undetermined. OTF-S incidents in 2023 are shown as circles. OTF-W incidents detected pre-2023 are shown as squares. The geographical location of potential TB hotspots are shown in orange and confirmed hotspots are brown. Most TB incidents in 2023 were located within the central North Yorkshire, the rest were distributed throughout the county, and are described in more detail in the main body of text.

As can be seen from Figure 6 and Appendix 3 (Table 5), OTF-W incidents in Yorkshire and Humberside in 2023 were mainly attributed to inward movements of TB-infected cattle.

There was uncertainty surrounding the likely source of infection for the one OTF-W (B3-11) incident in West Yorkshire. Although there are few cattle movements into the herd, this risk pathway was associated with a medium likelihood of introducing infection. Badgers and deer were reported to be present in the area and some practices which may increase contact between these and cattle were reported but signs of activity were not reported. There were not opportunities for contiguous cattle contact. The origin remains obscure.

A review of incidents in West Yorkshire over recent years is currently being carried out. There have been 6 OTF-W incidents in the west of this county since 2020 and all except one were caused by infection with clade B3-11 of M. bovis. It was not possible to isolate the bacterium from the visible lesions found in cattle removed from the remaining infected herd. Those OTF-W incidents are geographically dispersed, but there were OTF-S incidents near each of them. WGS shows that 2 of these incidents in the south of West Yorkshire are genetically closely related. Purchase of infected cattle is the most likely risk pathway for one of these, but the other one remains obscure. Links between the 2 have not been identified. The other 3 OTF-W incidents for which WGS is available are separated by at least 9 Single Nucleotide Polymorphisms (SNPs). Purchase of infected cattle is a likely risk pathway for one of these other incidents, but others are more uncertain. Investigation is ongoing but it seems unlikely that all these OTF-W incidents are linked. However, each will need to be considered in relation to the nearby OTF-S incidents.

Three of OTF-W incidents in Humberside were attributed to infected cattle movements. The source of one of the OTF-W incidents in the north of the county remains unclear.

Figure 6: Map of the infection pathways recorded with the highest level of certainty, for OTF-W incidents, and the location of OTF-S incidents in Yorkshire and Humberside which started in 2023. ‘Local cattle’ refers to residual infection and contiguous cattle risk pathways. ‘Purchased’ refers to infected cattle movement risk pathways. ‘Wildlife’ refers to both badger and other wildlife risk pathways.

Figure 6 description: A map of Yorkshire and Humberside showing the geographical location of cattle holdings with new OTF-W incidents in 2023 and the most likely source of infection. OTF-W incidents are shown as circles in different colours which represent the source of infection. Blue represents local cattle, brown represents purchased cattle, and green represents wildlife. New OTF-S incidents in 2023 are shown as triangles. The geographical location of potential TB hotspots are shown in orange and confirmed hotspots are brown. Most OTF-W incidents in 2023 had purchased cattle as the source of infection pathway with the highest level of certainty, the sources for 2 incidents were undetermined and one was attributed to wildlife.

Figure 7 shows the hotspot areas and radial surveillance zones instigated by APHA around OTF-W incidents in this part of the LRA since 2014. 

In the centre of North Yorkshire, there is a cluster of incidents that have triggered radial zones over the past few years, with 4 new OTF-W incidents in 2023 (2 associated with clade B3-11 of M. bovis, one with clade B6-62 and another with clade B6-51). The 2 new incidents attributable to clade B3-11 were both disclosed by trace tests of animals that had originated from the same farm, which had a history of TB incidents, yielding closely related B3-11 isolates. The B6-62 incident was attributed to purchase of infected cattle. The clade B6-51-associated incident was a slaughterhouse case that had originated from a Cumbrian farm which is experiencing an explosive incident caused by the same clade of M. bovis.

The index cases for the radial zones set up in 2021 and 2022 in this area also had clade B3-11 isolated. All these recent incidents in this area have been attributed to cattle movements, irrespective of the clade isolated. The 2020 incidents in this area had genotype 25:a isolates, which can be equivalent to clade B3-11, but again, all these incidents were attributable to infected cattle movements. Recent application of whole genome sequencing has further supported this and there is no currently available evidence to support locally spreading infection.

Two new OTF-W incidents, also both with clade B3-11 and attributed to cattle movements triggered radial zones in 2023 to the east of the central cluster (Figure 7). Both radial zones remain active and occurred in areas where previous radial zones were initiated between 2014 and 2020. The previous radial zones were triggered by incidents attributable to different clades.

One new radial zone was set up in 2023 to the north of North Yorkshire near the border with Cleveland (Figure 7). The index case for this zone yielded a clade B4-11 isolate and was attributed to purchase of infected cattle. It was near 2 active radial zones from 2022 and prior. The 2022 radial zone was triggered by a B6-11 isolate with an unknown origin.

In the south of North Yorkshire, there was one new radial zone associated with an incident which yielded a clade B6-85 isolate (Figure 7). There had been no radial zones triggered in this area since 2014. Cattle movements were the likely source of infection for this incident.

To the west of the county there were no new OTF-W incidents resulting in radial zones in 2023. There were 2 pre-existing radial zones from 2021 and from 2022 still active. The 2021 radial zone was just outside the eastern boundary of potential hotspot HS27 and had been triggered by an incident associated with clade B3-11. The 2022 radial zone was inside HS27 and triggered by an incident with a clade B6-11 isolate.

In West Yorkshire, there was one radial zone triggered after the detection of an OTF-W incident near the border with South Yorkshire (Figure 7). The clade isolated was B3-11 but the likely source of this infection remains obscure as described earlier in Figure 6. There was one active zone that began in 2022 around the same area following the detection of a B3-11 isolate originally thought to be caused by infected cattle movements, but now appears more uncertain. Nevertheless, WGS shows that the isolates from these 2 OTF-W incidents in 2022 and 2023 are not closely related, which reduces the likelihood of local spread.

One radial zone was triggered by an incident caused by clade B3-11 in South Yorkshire, south of Doncaster, in 2023 (Figure 7). This was attributed to the movement of infected cattle.

Radial zones were triggered by the 4 new OTF-W incidents detected in Humberside in 2023. One incident with a clade B6-11 isolate resulted in a radial zone around the M62 on the border with North and South Yorkshire (Figure 7). Another radial zone was set up further east in the region around Goole by an incident also attributable to clade B6-11 (Figure 7). Near Barton-upon-Humber there was one radial zone triggered by an incident associated with B3-11. (Figure 7). To the north of the county, a radial zone was initiated by an OTF-W incident caused by clade B3-11. Three of these incidents were attributable to infected cattle movements, but the source of the incident in the north of the county remains obscure.

Figure 7: Hotspot areas and radial surveillance zones around OTF-W incidents that were active, completed or not instigated in Yorkshire and Humberside during 2023, by year of initiation.

Figure 7 description: A map of Yorkshire and Humberside showing the geographical location of hotspots and radial surveillance zones around OTF-W incidents in 2023. The radial zones are shown as circles. Active radial zones are shown as solid line circles, completed radial zones are shown as dotted line circles, and radial zones that were not instigated are shown as orange triangles. The colour of the circles represents the year in which the radial zone was instigated: 2023 is green, 2022 is blue, 2021 is pink and 2014 to 2020 is orange. The geographical location of potential TB hotspots are shown in orange and confirmed hotspots are brown. In 2023, there were new active radial zones throughout the county.

TB hotspots

Hotspot 27

Hotspot 27 (HS27) is located in the south-western corner of North Yorkshire and straddles the county boundary with Lancashire (Figures 5 to 7). It was set up in January 2020 following an incident from which genotype 17:z (clade B6-23) of M. bovis had been isolated.

During the reporting period, there were no new OTF-W incidents detected in the hotspot. A new OTF-W incident was disclosed in 2022, but this was associated with clade B6-11.

Since its implementation only one wild deer carcass has been submitted to APHA for examination, with negative culture results for M. bovis.

Three new OTF-S incidents were declared in 2023 on cattle farms around the perimeter of HS27, one of which overlapped the area.

This hotspot is currently undergoing a review process to consider its closure.

Hotspot 28

Hotspot 28 (HS28) was first set up 2020 in East Lincolnshire and could pose a risk to the region (WGS clade B3-11, genotype 25:a). The hotspot become confirmed in May 2023 following the detection of a badger with a B3-11 clade which was genetically similar to local cattle B3-11 isolates. Originally, a very small area of HS28 spanned into a small portion of south-east Humberside, but this boundary was redefined in late 2023 and no longer includes it. In the last 3 years, there have been no OTF-W incidents in the vicinity of the Humberside border. There was one OTF-S incident in the north-east of the hotspot in 2021. Further information can be found in TB surveillance in wildlife – confirmed hotspots in the Low Risk Area of England.

Skin test reactors and interferon gamma test-positive animals removed

During 2023, a total of 86 animals were removed as TB test reactors from herds affected by TB incidents in this region of the LRA. Of these, 51 were skin test reactors and 35 were positive by the supplementary interferon gamma (IFN-γ) blood test, as shown in Figure 8a and 8b. In 2022, 93 skin reactors and 27 IFN-γ test-positive animals were removed from herds with TB incidents in the region. The IFN-γ test has a higher sensitivity but lower specificity than the comparative skin test and so is likely to disclose more TB positive animals. It can also detect infection at an earlier stage of infection than the skin test.

In North Yorkshire, the number of skin test reactors decreased from 32 in 2022 to 28 in 2023, whereas the number of IFN-γ test positive cattle removed doubled from 16 in 2022 to 32 in 2023. Interferon gamma test-positive animals disclosed in North Yorkshire represented 91% of those removed in this region in 2023, up from 60% of all blood test positive animals slaughtered in 2022.

In West Yorkshire, the number of skin test reactors and IFN-γ test positive animals decreased from 30 and 11 in 2022 to 14 and 0 in 2023, respectively.

Humberside and South Yorkshire both sustained a slight increase in both the number of skin test reactors removed in 2023 compared to 2022.

Humberside

Year	Skin test reactors	Interferon gamma reactors	Total
2018	3	7	10
2019	0	0	0
2020	4	10	14
2021	2	4	6
2022	2	0	2
2023	4	3	7

North Yorkshire

Year	Skin test reactors	Interferon gamma reactors	Total
2019	28	25	53
2020	26	15	41
2021	24	27	51
2022	32	16	48
2023	28	32	60

Figure 8a: Number of skin test reactors and interferon gamma (IFN-γ) test-positive cattle removed for TB control reasons in Humberside and North Yorkshire, from 2019 to 2023.

Figure 8a description: Stacked bar chart showing the number skin test reactors and interferon gamma test positive animals removed from herds between 2019 and 2023 in North Yorkshire and Humberside. Skin test reactors are shown in blue and interferon gamma test positive animals shown in green. In Humberside there were 4 skin test reactors and 3 interferon gamma test positive animals removed from herds in 2023. In North Yorkshire there were 28 skin test reactors and 32 interferon gamma test positive animals removed from herds in 2023, as described in the main body of text.

South Yorkshire

Year	Skin test reactors	Interferon gamma reactors	Total
2018	12	11	23
2019	16	7	23
2020	4	0	4
2021	0	11	11
2022	2	0	2
2023	5	0	5

West Yorkshire

Year	Skin test reactors	Interferon gamma reactors	Total
2019	38	8	46
2020	17	4	21
2021	9	0	9
2022	30	11	41
2023	14	0	14

Figure 8b: Number of skin test reactors and IFN-γ test positive cattle removed by APHA for TB control reasons in South Yorkshire and West Yorkshire, from 2019 to 2023.

Figure 8b description: Stacked bar chart showing the number skin test reactors and interferon gamma test positive animals removed from herds between 2019 and 2023 in South Yorkshire and West Yorkshire. Skin test reactors are shown in blue and interferon gamma test positive animals shown in green. In South Yorkshire there were 5 skin test reactors and no interferon gamma test positive animals removed from herds in 2023. In West Yorkshire there were 14 skin test reactors and no interferon gamma test positive animals removed from herds in 2023, as described in the main body of text.

Main risk pathways and key drivers for TB infection

Evidence collected during APHA veterinary investigations into the source of infection within herds was used to inform this understanding. In 2023, 26 out of 36 (72%) of new TB incidents in Yorkshire and Humberside received a preliminary or final APHA veterinary investigation to identify the source of infection. The reduced number of investigations carried out in 2023 was due to the continued impact and diversion of field resource as part of the 2022 to 2023 avian influenza outbreak which continued into spring 2023, in addition to the bluetongue virus outbreak from summer 2023 onwards.

It can be challenging to retrospectively establish the route of infection for a TB incident herd. Ideally this investigation includes a thorough on-farm investigation and scrutiny of routinely collected data, such as cattle movement records, and the results of WGS where available. Up to 3 hazards and risk pathways were selected for each incident investigated. Each of these potential sources were given a score that reflects the likelihood of that pathway being the true one, based on the available evidence.

Details of the protocol used for these investigations, and the subsequent methodology used to calculate the weighted contribution of the different suspected sources of M. bovis infection can be found in the explanatory supplement to the annual reports 2023.

The key driver behind the TB incidents detected in Yorkshire and Humberside during 2023 was the introduction of undetected infected cattle. This was the main risk pathway identified, resulting in a weighted contribution of 49.4%. This is higher than the equivalent findings in 2022 and 2021, when this risk pathway represented a weighted contribution of 31% and 28%, respectively.

By contrast, exposure to infected badgers remained an uncommon risk pathway (11.9% compared to 10% in 2022 and 10.5% in 2021).

As in previous years, there was a substantial percentage of TB incidents in 2023 with an uncertain source of infection, with 19.6% of the herd incidents attributed to ‘other or unknown source’. This is lower than compared to 2022, where the source was unknown in 27% of TB infections. This category is added to those incidents in which there was high uncertainty around the selected pathways (view the explanatory supplement to the annual reports 2023 for methodology).

Forward look

Incidents in 2023 have contributed to the substantial evidence that TB in this region is being driven by purchase of infected cattle. Concern about this risk pathway is heightened following review of 2023 data due to the finding of a greater number of different clades from incidents in Yorkshire and Humberside. Purchasing cattle from areas or herds with a higher risk of TB heightens the risk of seeding infection from cattle into the local wildlife, resulting in more potential for local spread of infection and increased numbers of TB incidents in herds.

In 2023, a serious non-compliance case occurred in an OTF-S incident herd in North Yorkshire, that had been under OTF-S TB movement restrictions since February 2023. Animals were purchased and moved to and from the affected farm without the required licences from APHA and, in some instances, without proper TB post-movement (post-import) tests.

Non-compliance with TB control regulations puts neighbouring herds and local wildlife at risk of infection, which directly compromises the favourable TB status of Yorkshire and Humberside, where there are very low levels of TB infection. This risk must be addressed by continued engagement with the farming industry to ensure that everyone is equally aware of, and aims to minimise, the risk from purchasing cattle.

The promotion and use of interactive mapping tools interactive mapping tools (ibTB) may help to mitigate some of the risk from cattle movements. This, coupled with further stakeholder engagement on good herd biosecurity practices will help to maintain and reduce the low incidence of TB we currently enjoy across the region.

The ongoing routine and targeted TB surveillance methods for cattle are critical in enabling Yorkshire and Humberside to maintain its low incidence of TB. Radial testing, post-movement and contact tracing bovine tests remain key to promptly disclose incidents and limit the potential for further spread. If the combination of these different testing regimes alongside routine surveillance continues, there is a good prospect that the region of Yorkshire and Humberside will maintain its low TB risk status.

Appendix 1: cattle industry demographics

Table 1: Number of cattle herds by size category in Yorkshire and Humberside as of 31 December 2023 (RADAR data on number of holdings in the report year)

Size of herds	Number of herds in Humberside	Number of herds in North Yorkshire	Number of herds in South Yorkshire	Number of herds in West Yorkshire
Undetermined	6	33	2	2
1 to 50	296	1,218	208	582
51 to 100	109	538	62	116
101 to 200	108	524	50	104
201 to 350	44	311	28	48
351 to 500	13	97	13	19
Greater than 500	10	131	5	10
Total number of herds	586	2,852	368	881
Mean herd size	90	129	85	71
Median herd size	48	64	41	28

Table 2: Number (and percentage of total) of animals by breed purpose in Yorkshire and Humberside as of 31 December 2023

Breed purpose	Number (and percentage of total) cattle in Humberside	Number (and percentage of total) cattle in North Yorkshire	Number (and percentage of total) cattle in South Yorkshire	Number (and percentage of total) cattle in West Yorkshire
Beef	44,221 (83%)	238,187 (64%)	23,216 (73%)	43,572 (69%)
Dairy	7,195 (13%)	117,885 (32%)	7,078 (22%)	16,542 (26%)
Dual purpose	1,362 (2%)	10,340 (2%)	1,123 (3%)	2,312 (3%)
Unknown	1 (0.002%)	102 (0.028%)	2	1 (0.0003%)
Total	52,779	366,514	31,419	62,427

Appendix 2: summary of headline cattle TB statistics

Table 3: Herd-level summary statistics for TB in cattle in Yorkshire and Humberside in 2023. (Sam data showing the number of herds flagged as active at the end of the report year)

Herd-level statistics	Humberside	North Yorkshire	South Yorkshire	West Yorkshire
(a) Total number of cattle herds live on Sam at the end of the reporting period	763	3,355	438	1,099
(b) Total number of cattle herds subject to annual TB testing (or more frequent) at the end of the reporting period (any reason)	57	278	40	169
(c) Total number of whole herd skin tests carried out at any time in the period	176	902	100	379
(d) Total number of OTF cattle herds having TB whole-herd tests during the period for any reason	157	822	91	307
(e) Total number of OTF cattle herds at the end of the report period (herds not under any type of TB movement restrictions)	747	3,300	422	1,077
(f) Total number of cattle herds that were not under restrictions due to an ongoing TB incident at the end of the report period	761	3,340	437	1,097
(g.1) Total number of new OTF-S TB incidents detected in cattle herds during the report period	1	11	2	8
(g.2) Total number of new OTF-W TB incidents detected in cattle herds during the report period	4	8	1	1
(h.1) Of the new OTF-W herd incidents, how many occurred in a holding affected by another OTF-W incident in the previous 3 years?	0	5	0	1
(h.2) Of the new OTF-W herd incidents, how many could be considered secondary to a primary incident based on current evidence?	0	0	0	0
(h.3) Of the new OTF-W herd incidents, how many were triggered by skin test reactors or twice-inconclusive reactors (2xIRs) at routine herd tests?	2	0	0	1
(h.4) Of the new OTF-W herd incidents, how many were triggered by skin test reactors or 2xIRs at other TB test types (such as forward and back-tracings, contiguous, check tests)?	2	8	1	0
(h.5) Of the new OTF-W herd incidents, how many were first detected through routine slaughterhouse TB surveillance?	2	2	0	0
(i.1) Number of new OTF-S incidents revealed by enhanced TB surveillance (radial testing) conducted around those OTF-W herds	0	3	1	5
(i.2) Number of new OTF-W incidents revealed by enhanced TB surveillance (radial testing) conducted around those OTF-W herds	0	1	0	0
(j) Number of OTF-W herds still open at the end of the period (including any ongoing OTF-W incidents that began in a previous reporting period)	2	10	1	0
(k) Number of OTF-W herds still open at the end of the period that were on a finishing unit	1	5	0	0
(l) New laboratory-confirmed incidents of M. bovis infection in non-bovine domestic species or captive deer detected during the report period (indicate host species involved)	0	0	0	0

Note (a) and (f) Cattle herd counts in Appendix 2 Table 3 and Appendix 1 Table 1 differ due to different data sources used. Appendix 1 Table 1 uses data from RADAR, while Appendix 2 Table 3 uses data from Sam.

Table 4: Animal-level summary statistics for TB in cattle in Yorkshire and Humberside during 2023.

Animal-level statistics (cattle)	Humberside	North Yorkshire	South Yorkshire	West Yorkshire
(a) Total number of cattle tested with tuberculin skin tests or additional IFN-γ blood tests in the period (animal tests)	19,377	107,197	9,217	21,943
(b.1) Reactors detected by tuberculin skin tests during the year	4	28	5	14
(b.2) Reactors detected by additional IFN-γ blood tests (skin-test negative or IR animals) during the year	3	32	0	0
(c) Reactors detected during year per incidents disclosed during year	1.40	3.16	1.67	1.56
(d) Reactors per 1,000 animal tests	0.36	0.56	0.54	0.64
(e.1) Additional animals slaughtered during the year for TB control reasons (dangerous contacts, including any first time IRs)	0	0	0	0
(e.2) Additional animals slaughtered during the year for TB control reasons (private slaughters)	0	1	0	0
(f) Slaughterhouse (SLH) cases (tuberculous carcasses) reported by the Food Standards Agency (FSA) during routine meat inspection	2	6	1	0
(g) SLH cases confirmed by M. bovis PCR testing or bacteriological culture	2	2	0	0

Note (c) Reactors detected during year per incidents disclosed during year, reactors may be from incidents disclosed in earlier years, as any found through testing during the report year count here.

Note (g) SLH cases confirmed by culture of M. bovis, not all cases reported are submitted for culture analysis. All cases reported are from any period prior to or during restrictions.

Appendix 3: suspected sources of M. bovis infection for all of the new OTF-W and OTF-S incidents identified in the report period

In 2023, 26 of 36 (72%) of new TB incidents in Yorkshire and Humberside received a preliminary or final APHA veterinary investigation to identify the source of infection. Not all investigations were carried out in 2023 was due to the continued impact and diversion of field resource as part of the 2022 to 2023 Avian Influenza outbreak which continued into spring 2023, in addition to the Bluetongue Virus outbreak from summer 2023 onwards.

Each TB incident could have up to 3 potential risk pathways identified. Each risk pathway is given a score that reflects the likelihood of that pathway bringing TB into the herd. The score is recorded as either:

• definite (score 8)
• most likely (score 6)
• likely (score 4)
• possible (score 1)

The sources for each incident are weighted by the certainty ascribed. Any combination of definite, most likely, likely, or possible can contribute towards the overall picture for possible routes of introduction into a herd.

If the overall score for a herd is less than 6, then the score is made up to 6 using the ‘Other or unknown source’ option. Buffering up to 6 in this way helps to reflect the uncertainty in assessments where only ‘likely’ or ‘possible’ sources are identified.

Table 5 combines the data from multiple herds and provides the proportion of pathways in which each source was identified, weighted by the certainty that each source caused the introduction of TB.

The output does not show the proportion of herds where each pathway was identified (this is skewed by the certainty calculation).

WGS of M. bovis isolates can be a powerful tool in identifying a likely source of infection, however WGS clades have not been determined for OTF-S herds. As a result of varying levels of uncertainty, only broad generalisations should be made from these data. A more detailed description of this methodology is provided in the explanatory supplement for the annual reports 2023.

Table 5: Suspected sources of M. bovis infection for the 26 new TB incidents that received a veterinary investigation in Yorkshire and Humberside in 2023.

Source of infection	Possible (1)	Likely (4)	Most likely (6)	Definite (8)	Weighted contribution
Badgers	7	2	3	0	11.9%
Cattle movements	5	3	8	2	49.4%
Contiguous	2	0	0	0	1.3%
Residual cattle infection	0	0	1	0	1.9%
Domestic animals	0	0	0	0	0.0%
Non-specific reactor	2	0	1	0	4.5%
Fomites	6	0	0	0	3.7%
Other wildlife	4	3	0	0	7.9%
Other or unknown source	2	0	0	0	19.6%

Please note each TB incident could have up to 3 potential pathways so totals may not equate to the number of actual incidents that have occurred.