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Improving cattle traceability reduces the risk of large disease outbreaks

Summary 

Government agencies have a number of potential intervention strategies available to contain the size of a disease outbreak. The effectiveness of certain disease control strategies is dependent on the accuracy of available data. Tracing susceptible animals that have been in-close contact with known or suspected infectious livestock underpins a number of intervention strategies.

In Scotland, before January 2017 there was a derogation to cattle movement legislation known as ‘CTS Links’. This derogation allowed farmers to move cattle between pre-registered holdings without notifying the British Cattle Movement System (BCMS).

EPIC scientists’ work to characterise the extent of CTS linked premises and model disease spread with or without the CTS links system in place, showed that disease outbreaks could spread further through linked premises. This evidence underpinned the decision by Scottish Government to remove the CTS linked holding derogation.

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Update 03/01/2018

In ScotMoves first year of operation more than 4,000 farmers registered on the system recording nearly 500,000 cattle movements. 

The information on the location of cattle in Scotland contained in the ScotMoves system provides greater reassurance to government and keepers that Scotland is well placed to prevent and control exotic diseases such as Foot and Mouth and endemic diseases such as Bovine Virus Diarrhoea.

Fergus Ewing, Rural Economy Secretary, 2018

ScotMoves also provides added reassurance in checking that cattle in Scotland continue to meet the eligibility criteria for BSE Negligible Risk which was achieved in May 2017.

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Introduction

Livestock disease outbreaks have a significant financial cost to public and private sector. The 2001 UK Foot-and-Mouth Disease outbreak cost an estimated £8bn. Outbreaks have a detrimental impact on animal welfare and can have a devastating effect on farmers, their families and communities where disease occurs.

There is a legal requirement for cattle movements in Great Britain (GB) to be recorded centrally. Farmers record individual cattle moving on and off the farm with the British Cattle Movement System (BCMS), which administers a system called the Cattle Traceability System (CTS). In Scotland until this year there was derogation to this legislation known as ‘CTS Links’, which allowed farmers to move cattle between pre-registered holdings without notifying BCMS. Farmers were instead required to keep a record of cattle moved under the CTS links rule in the on-farm records where the animal’s location was last notified to BCMS. Multiple premises can potentially be linked in this way forming a network through which cattle can be moved while never being recorded.

In a disease outbreak, BCMS is the primary source of information for identifying and tracing potentially infected cattle. Do these ‘missing’ animals pose a problem in managing a disease outbreak? 

Research underpinning the evidence

EPIC conducted research to identify the extent of gaps in our knowledge to adequately conduct livestock tracings due to the derogation ‘Cattle Tracing System (CTS) linked holdings’. The research was carried out using three types of data analysis:  

1)   Network modelling analysis of Agricultural Census records, CTS linked holdings register and BCMS movement records were used to identify: 

  • number of linked holdings in each network
  • distances between holdings in a linked network
  • number of cattle within individual holdings
  • number of cattle in a network of linked holdings
  • a GB wide ‘geographic footprint’ of networks 

2)   A disease spread model was developed to estimate the size and geographic spread of a disease outbreak in the presence and absence of the CTS links derogation. 

3) A joint EPIC/NFUS farmer opinion survey was conducted in order to determine the importance of CTS links to farmers. 

Impact 

Quantifying the extent of unrecorded cattle moves:  

It is know that since 2008 the number of registered CTS linked holdings has increased year on year up to 2014. In 2013, premises with CTS Links equated to more than 500,000 cattle (1.8M national herd) whose location recorded in BCMS is potentially different to their actual location. 

Because holdings could register multiple links networks of linked holding formed. The largest of the networks consisted of 334 holdings involving 56,000+ cattle. 

These findings were presented to policy makers and industry representatives to identify the scale of unrecorded cattle moves. Based on the evidence presented by EPIC, additional research was commissioned by Scottish Government to identify the likely impact of linked holdings on livestock disease spread. 

“The analysis of CTS Links carried out by EPIC has highlighted the disease risks to Scottish Government; the data and graphics have been used in discussions within Scottish Government and with the livestock sector to stimulate thinking about possible solutions.”

Dr Nick Ambrose, Scottish Government, 2015

Estimating the impact of CTS linked holdings on disease spread: Network analysis and simulation modelling  allowed EPIC scientists to estimate the size and spread of potential future cattle disease outbreaks. While the extent to which CTS links are actually used is unknown, even with a small probability of usage, the model outputs showed the potential greater disease spread in the presence of CTS links. This evidence underpinned the decision by Scottish Government to remove the CTS linked holding derogation. 

“Fundamentally, it is about creating a 21st century national traceability system that covers all cattle in order to protect the health of Scotland’s livestock better against the risk of disease. That traceability will give us the tools that we need to control an outbreak of a notifiable disease effectively, and it will help to maintain and enhance confidence in the provenance of our livestock and of our quality meat.”

Fergus Ewing (MSP): The Cabinet Secretary for Rural Economy and Connectivity. Statement to Scottish Parliament (21/12/2016)

EPIC’s advice supported a change to Scotland’s legislation governing cattle movement: The advice to remove the CTS links derogation has wider benefits to Scottish government also ensures that Scottish Government does not lose out on European funding. 

“The third reason to change the system is that there is no legal provision in European legislation for the use of CTS links, so the system’s continued use poses a risk of disallowance to the Scottish Government of around £2.5 million initially, and of more than £800,000 per annum thereafter.”

Fergus Ewing (MSP): The Cabinet Secretary for Rural Economy and Connectivity Statement to Scottish Parliament (21/12/2016)

Replacement of CTS Links by ScotMoves: EPIC in conjunction with NFUS undertook an on-line survey to capture farmer’s experience of CTS links. The findings of the survey contributed to the design of a new recording system, ScotMoves. The survey particularly highlighted that any replacement of the links system would not be likely to add any additional administration burden for recording. 

“It is important to bear in mind that the new ScotMoves system does not place any additional requirements on keepers. It is simply a new way to record the same information that they previously recorded in their on-farm holding register.”

Scottish Government website

Standstill regulation review: In the EPIC/ NFUS CTS Links Survey, standstill regulations were an important issue for the cattle industry. Standstill regulations govern the time period between livestock moving onto a farm, and others being allowed to move off.  In the case of cattle this is 13 days. The CTS links derogation also exempted linked moves from standstill regulations. The removal of CTS linked holdings and subsequent improvement in cattle traceability has also driven a review of the standstill regulation. 

EPIC is currently working with Scottish Government Animal Health and Welfare Division to provide analysis on the impact of reducing standstill days given the improvement ScotMoves brings to traceability. The initial focus of the work investigates how changes to standstill regulations could impact on FMD disease transmission. An important factor when contemplating legislative changes that could alter individual decision-making is the knock-on effect this could have on the structure of the livestock movement network itself. EPIC scientists are using network analysis and mathematical models to investigate how changing the local contact structure simultaneously through movement restrictions of different length (13 days / 6 days) and re-directed livestock movements between holdings and markets might affect the final size of a simulated FMD outbreak. Model outputs will include scenarios with and without exemptions to the standstill rules to identify the size of epidemics, independent of the length of the standstill period. These model outputs will help understand the impact of potential regulation change regarding reducing the standstill period in combination with standstill exemptions and additional risk for FMD. Reviewing standstills also helps Scottish Government towards achieving the recommendations of the Pack review on reducing government red tape. 

“The chief veterinary officer has already agreed that that [a review of rules on standstill] would be a valuable exercise, for the reason that the data that will come forward over the next year through the new ScotMoves system will be of considerable value in reviewing the standstill regime. That is one of the potential benefits of the new system.”

Fergus Ewing (MSP): The Cabinet Secretary for Rural Economy and Connectivity. Statement to Scottish Parliament (21/12/2016) in answer to a question by Richard Lyle (Uddingston and Bellshill) (SNP) requesting a review of rules on standstill following the launch of ScotMoves.

Conclusion 

The work of EPIC scientists underpinned and informed the evidence-based change in Scottish animal movement legislation. A key benefit in the ScotsMoves system is to allow Scottish Government to better utilise resources to improved traceability, disease detection and control. Ultimately this change should reduce the risk of large outbreaks of diseases such as foot and mouth disease. 

“The system is designed to help [the] industry protect against the unthinkable prospect of disease. By enabling us to have quick access to high-quality and accurate information, we are better placed to deploy our resources effectively to better protect Scotland’s livestock from disease.”

Sheila Voas Scotland’s chief veterinary officer (Scotsman 18/01/17)

Further reading

ScotEID: ScotMoves

ScotMoves one year on

CTS Links

Orton RJ, et al., 2012. Risk of Foot-and-Mouth Disease spread due to sole occupancy authorities and linked cattle holdings.

Enright J. and Kao RR, 2016. A descriptive analysis of the growth of unrecorded interaction amongst cattle-raising premises in Scotland and their implications for disease spread.

Meeting of the Parliament Wednesday 21 December 2016: Protecting Scotland’s Livestock, The Cabinet Secretary for Rural Economy and Connectivity (Fergus Ewing)

Contributors

Jess Enright led the data analysis and developed the network and disease spread modelling. Jess is a lecturer in statistics at Stirling University.

Sibylle Mohr brought together the standstill work, with Mikhail Churakov (initial modelling) and Michael Deason (network rewiring). Sibylle is a mathematical modeller at the University of Glasgow. Mikhail conducted the work whilst at the University of Glasgow, and is now a postdoctoral researcher at the Institut Pasteur. Michael is a research assistant at the University of Glasgow.

Rowland Kao provided oversight of the analysis. Rowland is the Professor of Mathematical Population Biology at the University of Glasgow.

Emily Hotchkiss developed and analysed the farmer CTS links experience survey. Emily is a veterinary epidemiologist and conducted the work whilst at the Moredun Research Institute.

Lisa Boden facilitated communication at the science-policy interface between Scottish Government policy-makers,  livestock industry representatives and EPIC members. Lisa is a veterinary epidemiologist at the University of Glasgow

The research was conducted in collaboration with members of the Scottish Government Animal Health and Welfare Division and, National Farmers Union Scotland.

The research was funded by the Scottish Government as part of EPIC: Scotland’s Centre of Expertise on Animal Disease Outbreaks

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