Research and analysis

North East of England (low risk area) year end report 2022

Updated 20 November 2023

Introduction

The Low Risk Area (LRA) of England was established in 2013. In 2014 this area was incorporated into the UK government’s strategy to achieve Officially Tuberculosis-Free (OTF) status for England by 2038. A key action was to recognise the different levels of bovine tuberculosis (TB) in different parts of the country and to vary the approach to control accordingly. Overall, the LRA has a very low and stable incidence of infected herds. The current strategy seeks to rapidly control infection when it arises through:

• high sensitivity testing of affected herds
• temporarily enhanced local surveillance (radial and hotspot testing)
• mandatory pre- and post-movement testing of cattle entering the LRA from higher risk areas of the UK

The aim 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 2022 in cattle herds in the North East of England, which includes Northumberland, Tyne and Wear, Durham, Cleveland which are part of the LRA. In 2022, 2% of all new TB incidents in the LRA were detected in the North East of England.

TB in cattle and other mammals is primarily caused by 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 individuals involved in the control of TB, both locally and nationally. This includes, but is not limited to farmers, veterinarians, policy makers and 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 2022.

Types of TB incident

Unless otherwise specified, this report includes all new TB incidents detected during the reporting period, 1 January to 31 December 2022. This includes both ‘Officially Tuberculosis-Free Status Withdrawn’ (OTF-W) and ‘Officially Tuberculosis-Free Status Suspended’ (OTF-S) incidents.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, or SICCT test) with either typical lesions of TB identified at post-mortem (PM) meat inspection, or at least one animal with M. bovis-positive culture results from tissue samples collected from carcases during the PM inspection, or both.

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

Cattle industry

The cattle industry in the North East of England is predominantly beef-based. Cattle herd sizes vary between counties, as shown in Appendix 1, with over 90% of the region’s cattle located in Northumberland and County Durham. Breeding suckler herds account for most of the cattle population. However, there are also many finishing herds which rely on the continuous supply of store cattle sourced locally and from farms outside the region, such as those in the High Risk Area (HRA) in the west of England, Wales, and Northern Ireland.

There are 7 livestock markets in the region. The biggest one is Darlington Market in County Durham, which holds both ‘green’ (regular) and ‘red’ (TB dedicated slaughter gathering) status cattle sales. It is the main slaughter market for fattening herds and holds slaughter gatherings accepting cattle from TB-restricted holdings, which are destined for slaughterhouses. The main market in Northumberland is Hexham Market, which holds ‘green’ sales only, including sales for slaughter cattle from Officially TB Free (OTF) herds.

There are 7 Licensed Finishing Units (LFUs), all of which are in County Durham. These units are licensed by the Animal and Plant Health Agency (APHA) and require their cattle to be housed all the time. Conditions of approval include demonstration of strict biosecurity protocols and wildlife proofing of the unit. Cattle in LFUs must be sourced from unrestricted (Officially TB Free) herds and subject to pre-movement TB testing when required but are exempt from post-movement or tracing testing.

The traditional farming practice in the North East of England is for cattle to graze from April to late October and then to be housed over the winter months. There are some common land parcels and if any TB incidents occur in herds which use these areas, it can result in additional tracing activity.

New TB incidents

The number of new TB incidents detected in the North East of England decreased between 2021 and 2022, from 4 to 3. Total incident numbers have been decreasing from a high of 10 in 2020, as shown in Figure 1. There was one new OTF-W incident (unchanged from 2021) and 2 new OTF-S incidents (compared to 3 in 2021). The geographic distribution of these incidents across the region was as follows:

• Northumberland reported no new TB incidents in 2022, down from 3 reported in 2021
• Durham reported one OTF-S incident in 2022, unchanged from the previous year
• Cleveland reported 2 new TB incidents in 2022, one OTF-S and one OTF-W. This was up from no incidents in 2021
• Tyne and Wear has reported no TB incidents since the 1990s

There were no unusual TB incidents in cattle or reports of TB in other farmed or captive non-bovine species in the North East region in 2022. There were no confirmed or suspected cases of zoonotic (human) M. bovis infection found either.

Figure 1: Annual number of new TB incidents (OTF-W and OTF-S) in the North East, from 2013 to 2022

County and year	OTF-W incidents	OTF-S incidents	Total
Cleveland 2013	0	0	0
Cleveland 2014	0	0	0
Cleveland 2015	0	0	0
Cleveland 2016	0	0	0
Cleveland 2017	0	1	1
Cleveland 2018	0	0	0
Cleveland 2019	0	0	0
Cleveland 2020	2	0	2
Cleveland 2021	0	0	0
Cleveland 2022	1	1	2
Durham 2013	2	0	2
Durham 2014	3	0	3
Durham 2015	1	0	1
Durham 2016	2	2	4
Durham 2017	2	1	3
Durham 2018	0	1	1
Durham 2019	0	0	0
Durham 2020	0	1	1
Durham 2021	0	1	1
Durham 2022	0	1	1
Northumberland 2013	0	2	2
Northumberland 2014	1	0	1
Northumberland 2015	0	2	2
Northumberland 2016	1	3	4
Northumberland 2017	0	2	2
Northumberland 2018	0	3	3
Northumberland 2019	1	5	6
Northumberland 2020	1	6	7
Northumberland 2021	1	2	3
Northumberland 2022	0	0	0

Note: Tyne and Wear not shown as there have been no new TB incidents since the 1990s.

Disclosing test type

As displayed in Figure 2, the new TB incident in Durham was detected by pre-movement testing (PRMT) in a dealer herd subjected to annual surveillance TB testing. One TB incident was detected in Cleveland by routine herd testing (RHT), and the other was detected by slaughterhouse surveillance.

The TB incidents occurred in herds with no previous history of TB. This is reflective of the predominant risk pathway in this area which is purchase of infected cattle.

Figure 2: Number of new TB incidents (OTF-W and OTF-S) in the North East, in 2022 according to the surveillance method that detected them

County	Pre-movement test	Routine herd test	Slaughterhouse	Total
Durham	1	0	0	1
Cleveland	0	1	1	2

The headline cattle TB statistics for North East of England is summarised in Appendix 2.

Duration of TB incidents

A total of 5 TB incidents were resolved during 2022. Of these, 3 were the new TB incidents that started in 2022 and 2 started in 2021.

The new OTF-W incident detected in Cleveland quickly resolved, in 153 days, which accounts for the requisite minimum of 2 initial statutory short interval tests (SIT) and any time elapsing for the reactor removal. The 2 new OTF-S incidents were also resolved rapidly, in 78 and 73 days. The 2 ongoing incidents from 2021 lasted for 168 days (OTF-W) and 109 days (OTF-S).

There were no persistent incidents (under movement restrictions for more than 550 days) in the region.

By the end of 2022 there were no ongoing cattle TB incidents in this region.

Geographical distribution of TB incidents

In 2022, all new TB incidents were detected in the south of the region, close to the North Yorkshire border (Figure 3).

The one OTF-W incident in Cleveland was disclosed in the south-west of the county and was associated with clade B6-62 of M. bovis. The one OTF-S incident was disclosed in the south-east of the county in an area with a higher cattle density.

In Cleveland, the single OTF-W incident detected in 2022 with clade B6-62, affected a 60-cattle fattening herd. An animal resident on this holding for 6 months was found to have suspected lesions of TB at commercial slaughter. Subsequent laboratory test showed that it was polymerase chain reaction (PCR) and culture positive for M. bovis. Following 2 statutory short interval herd tests

SIT and a supplementary interferon gamma (IFN- γ) blood test with negative results, the herd regained its OTF status in August 2022.

The OTF-S TB incident that occurred in the south-east of Cleveland involved a 500-cattle dairy herd. The reactor animal was a seven-month-old heifer born on the farm, which had been permanently housed. This animal had no visible lesions of TB at slaughter and was also culture negative. After one statutory SIT with negative results the herd regained its OTF status. The origin of this TB incident is unknown.

In Durham, the only OTF-S incident was in the south-west of the county, as shown in Figure 3. This TB incident affected a small beef fattening herd and cattle dealer subjected to annual surveillance testing (and hence pre-movement testing too). The reactor was a 10-month-old animal which had been purchased from within the LRA. It had been purchased 3 months prior to the incident and was identified as a reactor at a pre-movement test. The origin farm had no history of TB. This reactor animal had no visible lesions at slaughter, and it was culture negative. After one compulsory SIT with negative results, the herd regained its OTF status in August 2022. The origin of this incident is unknown.

In Northumberland, there was one OTF-W incident disclosed in 2021, associated with clade B5-11. This incident was still open at the start of 2022 and the location is in the east of the county indicated in Figure 3 with a square symbol. There were no further incidents in the same region in 2022.

Figure 3: Location of cattle holdings in the North East of England with new TB incidents (OTF-W and OTF-S) in 2022, and cattle holdings with pre-2022 OTF-W incidents still ongoing at the beginning of 2022, overlaid on a cattle density map. Note that ‘OTF-W Introduced 2022’ refers to OTF-W incidents in which cattle movements were the most likely source of infection identified through an APHA veterinary investigation.

The one OTF-W incident in the south-west of Cleveland from which clade B6-62 was isolated was most likely attributed to the introduction of undetected infected animals (Figure 4). The index animal identified as a TB slaughterhouse case was born in Leicestershire (Edge Area) and had subsequently moved through 3 other holdings prior to arriving on the farm where it triggered the incident. One of these holdings is in the homerange area associated with B6-62.

Figure 4: Map of the source of infection pathway recorded with the highest level of certainty, for OTF-W incidents, and the location of OTF-S incidents in the North East of England which started in 2022. Local cattle refer to residual infection and contiguous cattle risk pathways. 'Purchased’ refers to cattle movement risk pathways. Wildlife refers to both badger and other wildlife risk pathways.

New OTF-W incidents of TB throughout the North East of England continue to arise very sporadically. The new OTF-W incident detected in the south-west of Cleveland occurred in an area without a recent history of TB, as shown in Figure 5.

In Northumberland, the single OTF-W incident detected in 2021 (clade B5-11) was located close to another OTF-W incident detected in 2020, but this had a different clade (B6-51), so these 2 are likely to be unrelated.

The new OTF-W incident in Cleveland was the first incident in the south-west of the county for at least 10 years.

Figure 5: Hotspot areas and radial surveillance zones around OTF-W incidents that were active, completed or not instigated in the North East of England during 2022, by year of initiation.

Potential or confirmed TB hotspots

There was no potential or confirmed TB hotspot areas in any of the counties in the North East of England in 2022. Only a single new radial zone was instigated in 2022, around the single OTF-W incident found in the south-west of Cleveland. One radial zone from 2021 was still active in Northumberland, as shown in Figure 5. This enhanced surveillance instigated in 2022 in Cleveland is still on going with no further TB incidents found at the time of writing this report, showing that TB has not spread in the locality.

Two OTF-W TB incidents that gave rise to radial zones in 2020 and 2021 were in close proximity, but as described above, it was concluded that these incidents were not related to one another following both APHA veterinary investigations and whole genome sequencing (WGS) analysis.

Skin test reactors and interferon gamma test positive animals removed

As presented in Figure 6, the number of reactors removed for TB control purposes in the North East of England increased in 2022 compared to 2021, from 9 to 12. Of the 12 cattle removed for TB control purposes in 2022, 2 were skin test reactors, down from 4 in 2021. A further 10 were positive on the IFN-γ test, up from 5 in 2021.

In Cleveland, there was one skin test reactor, compared to no skin test reactors in 2021. No IFN-γ test positive animals were detected, which was down from 5 in 2021.

In 2022, one skin test reactor was detected in Durham, compared to one in 2021. No skin test reactors were detected which was the same in 2021.

In Northumberland there were 10 IFN-γ test positive animals, which was an increase from none in 2021. These animals came from a herd with an OTF-W incident that began in 2021, which was later resolved in 2022. None of the IFN- γ test positive animals were found with visible lesions at slaughter. No skin test reactors were detected, compared to 2 in 2021.

Figure 6: Number of cattle that tested positive to the skin test or interferon gamma test and were removed by APHA for TB control reasons in the North East, from 2017 to 2022.

County and year	Skin test	Interferon gamma test	Total
Cleveland 2017	2	0	2
Cleveland 2018	0	0	0
Cleveland 2019	0	0	0
Cleveland 2020	3	2	5
Cleveland 2021	0	5	5
Cleveland 2022	1	0	1
Durham 2017	9	14	23
Durham 2018	1	0	1
Durham 2019	0	0	0
Durham 2020	1	0	1
Durham 2021	2	0	2
Durham 2022	1	0	1
Northumberland 2017	2	0	2
Northumberland 2018	4	0	4
Northumberland 2019	8	1	9
Northumberland 2020	11	17	28
Northumberland 2021	2	0	2
Northumberland 2022	0	10	10

The number of reactors removed, and the number of incidents detected gives an indication of the relative impact to the taxpayer in an area. The cost to the taxpayer is mainly due to the cost of compulsory government-funded post incident testing and payment of compensation for reactors removed.

There are also both direct and hidden costs and impacts to the farmers when an incident is detected. One of the main impacts of TB incidents is on the ability to move stock off the restricted premises, which can have adverse consequences on the numbers of breeding animals such as weaned beef calves and store cattle. The same applies to sourcing stock to replace the TB reactors removed, or other replacements. This proves even more difficult for pedigree animals.

Acquiring stock is not permitted until after the first short interval test has been completed. Following this, any movements on must be carried out under licence, which is only granted after a thorough veterinary risk assessment to ensure that mitigation measures are followed, and the disease has not spread. Another important consideration is that if cattle purchased during an incident become reactors at subsequent tests, there is a 50% reduction in the compensation paid to the farmer.

All these constraints affect the farmer’s normal trading practices and increases labour costs related to the increased testing requirements. Some of these factors also affect farms which fall within a radial surveillance zone.

Due to the low number of reactors disclosed in every incident in the region and the relative short duration of each incident, the impact of TB for farmers and the taxpayer was relatively low in comparison with other areas of the country where more reactors are removed, and persistent incidents are more frequent.

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 2022, all 3 (100%) new TB incidents in the North East of England underwent a preliminary or final APHA veterinary investigation to identify the source of infection.

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 2022.

Only cattle movements were identified as a key driver of the TB epidemic in the North East of England during 2022.

It should be noted that due to the small number of incidents, it is difficult to draw any firm conclusions for the aggregated data from veterinary investigations.

There was a high degree of uncertainty around the source of TB infections in 2022 as shown by the percentage of weighted source attribution ascribed to ‘other or unknown source’ (61%). This category is added to those incidents in which there was a high uncertainty around the selected pathways (see explanatory supplement to the annual reports 2022 for methodology).

Cattle movements (39%) was the only other risk pathway identified in the North East in 2022. It was selected as the most likely pathway for one incident, and possible for another as reported in Table 5, Appendix 3.

All the incidents in 2022 occurred in herds with no previous history of TB. This highlights that the LRA remains under threat of sporadic disease incursions. It also highlights the need to raise awareness within the industry of the TB risk associated with the purchase of cattle and the importance of careful sourcing of cattle replacements.

Most of the incidents in the North East in 2002 were OTF-S and these always carry a higher level of uncertainty around the sources of infection as, by definition, the WGS clade of M. bovis could not be determined.

Higher uncertainty also exists where very small number of reactors are identified. Most of the incidents in 2022 presented no more reactors at subsequent testing and this provides some assurance that there is minimal lateral spread of infection within herds.

There is currently no evidence of a wildlife reservoir of infection in the area, but this risk cannot be completely discounted and is carefully considered for each TB incident.

Forward look

The overall number of incidents decreased in 2022, compared to 2021. The North East of England remains one of the LRA regions with the lowest incidence of TB in cattle. A low number of reactors are typically disclosed in each incident, and incidents have a relatively short duration. As a result, the impact of TB for farmers and the taxpayer was relatively low in the North East in 2022 in comparison with other areas of the country.

Timely detection of infected animals and subsequent removal is one of the key steps in infectious disease control. This is likely to have played a significant role in the protection of the remaining susceptible cattle population and keeping the region relatively free of TB. It is therefore vital to maintain the passive and active TB surveillance within the LRA.

The consensus is that more local farmer meetings could help to increase awareness of TB. This should encourage careful sourcing of cattle and reduce the risk of introducing TB into the region by the movement of infected cattle from higher TB risk areas of the United Kingdom. To further reduce TB incidence and maintain LRA status, enhanced TB surveillance measures need to be continued, together with the implementation of responsible cattle purchasing policies.

Given the history and the effectiveness of controls, it is very likely that the North East of England will continue to experience a very low number of sporadic TB incidents over the next few years. Given the objective of achieving TB OTF status for the whole of England by 2038, a focus is needed on the farming community’s attitude towards TB control and sourcing cattle to this area.

Appendix 1: cattle industry demographics

Table 1: Number of cattle herds by size band in the North East of England at 31 December 2022, by county (RADAR data)

Size of herds	Number of herds in Cleveland	Number of herds in Durham	Number of herds in Northumberland	Number of herds in Tyne and Wear
Undetermined	1	7	11	1
1 to 50	53	399	281	28
51 to 100	24	158	183	11
101 to 200	25	146	208	14
201 to 350	10	61	125	7
351 to 500	4	18	38	1
Greater than 500	5	25	36	0
Total number of herds	122	814	882	62
Mean herd size	114	100	146	86
Median herd size	64	51	89	54

Table 2: Number (and percentage of total) of animals by breed purpose in the North East of England at 31 December 2022, by county

Breed purpose	Number (and percentage of total) cattle in Cleveland	Number (and percentage of total) cattle in Durham	Number (and percentage of total) cattle in Northumberland	Number (and percentage of total) cattle in Tyne and Wear
Beef	10,949 (78%)	69,369 (85%)	118,163 (91%)	4,578 (86%)
Dairy	2,909 (20%)	10,259 (12%)	9,319 (7%)	457 (8%)
Dual purpose	83 (0.6%)	1,465 (1%)	1,472 (1%)	272 (5%)
Unknown	4 (0%)	15 (0.018%)	5 (0.006%)	0%
Total	13,945	81,108	128,959	5,307

Appendix 2: summary of headline cattle TB statistics

Table 3: Herd-level summary statistics for TB in cattle in the North East of England in 2022, by county

Herd-level statistics	Cleveland	Durham	Northumberland	Tyne and Wear
(a) Total number of cattle herds live on Sam at the end of the reporting period	147	981	1,087	78
(b) Total number of cattle herds subject to annual TB testing (or more frequent) at the end of the reporting period (any reason)	18	11	31	1
(c) Total number of whole herd skin tests carried out at any time in the period	68	150	259	17
(d) Total number of OTF cattle herds having TB whole herd tests during the period for any reason	59	148	243	17
(e) Total number of OTF cattle herds at the end of the report period (herds not under any type of Notice Prohibiting the Movement of Bovine Animals (TB02) restrictions)	144	968	1,084	77
(f) Total number of cattle herds that were not under restrictions due to an ongoing TB incident at the end of the report period	147	981	1,087	78
(g.1) Total number of new OTF-S TB incidents detected in cattle herds during the report period	1	1	0	0
(g.2) Total number of new OTF-W TB incidents detected in cattle herds during the report period	1	0	0	0
(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	0	0	0
(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 2 time inconclusive reactors (2xIRs) at routine herd tests?	0	0	0	0
(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)?	0	0	0	0
(h.5) Of the new OTF-W herd incidents, how many were first detected through routine slaughterhouse TB surveillance?	1	0	0	0
(i.1) Number of new OTF-S incidents revealed by enhanced TB surveillance (radial testing) conducted around those OTF-W herds	0	0	0	0
(i.2) Number of new OTF-W incidents revealed by enhanced TB surveillance (radial testing) conducted around those OTF-W herds	0	0	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)	0	0	0	0
(k) Number of OTF-W herds still open at the end of the period that are within a finishing unit	0	0	0	0
(l) New confirmed (positive M. bovis culture) incidents in non-bovine species detected during the report period (indicate host species involved)	0	0	0	0

Table 4: Animal-level summary statistics for TB in cattle in 2022

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) Slaughterhouse (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.

Animal-level statistics (cattle)	Cleveland	Durham	Northumberland	Tyne and Wear
(a) Total number of cattle tested with tuberculin skin tests or additional IFN-γ blood tests in the period (animal tests)	7,269	10,566	32,789	831
(b.1) Reactors detected by tuberculin skin tests during the year	1	1	0	0
(b.2) Reactors detected by additional IFN-γ blood tests (skin-test negative or IR animals) during the year	0	0	10	0
(c) Reactors detected during year per incidents disclosed during year	0.5	1	0	0
(d) Reactors per 1,000 animal tests	0.14	0.09	0.3	0
(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	0	0	0
(f) SLH cases (tuberculous carcases) reported by the Food Standards Agency (FSA) during routine meat inspection	1	3	4	0
(g) SLH cases confirmed by PCR testing or culture of M. bovis	1	0	0	0

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 2022, all 3 (100%) new TB incidents in the North East of England received a preliminary or final APHA veterinary investigation to identify the source of infection.

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 2022.

Table 5: Suspected sources of M. bovis infection for all new OTF-W and OTF-S incidents identified in the North East in 2022

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.

Source of infection	Possible (1)	Likely (4)	Most likely (6)	Definite (8)	Weighted contribution
Badgers	0	0	0	0	0%
Cattle movements	1	0	1	0	39%
Contiguous	0	0	0	0	0%
Residual cattle infection	0	0	0	0	0%
Domestic animals	0	0	0	0	0%
Non-specific reactor	0	0	0	0	0%
Fomites	0	0	0	0	0%
Other wildlife	0	0	0	0	0%
Other or unknown source	2	0	0	0	61%