Risk-based surveillance and testing defines government policy on bovine tuberculosis

Our research has developed a revised surveillance model for bovine tuberculosis (bTB) that underpins a new Scottish Government policy on bTB testing in Scotland. This has exempted 30% of Scottish herds from routine testing, with savings to Government of £150,000/year and a further £100,000 across the farming industry.

The problem

Prof Rowland Kao discussing this research and its impact

Bovine tuberculosis (bTB) is a bacterial infection which infects livestock and wildlife and has severe consequences for animal health, with associated damage and costs to the farming industry and government. The disease has been largely eliminated in many countries, but the control of bTB has proven problematic in the UK and Ireland, involving costly routine herd testing every 4 years.

In 2009 Scotland was designated as an officially (bovine) TB-free region, due to the substantially lower prevalence of bTB relative to other areas of Great Britain. This presented an opportunity for the farming industry and Scottish Government to reduce both the costs associated with routine testing (which cost around £2m per year) and the risks associated with herding cattle for testing; bTB testing is one of the most hazardous tasks undertaken by veterinarians and farmers.

However, to retain officially bTB-free status Scotland must continue to demonstrate maintenance of freedom from the disease. The challenge was to identify revised testing strategies that reduce costs, but maintain surveillance levels for bTB.

Our role

A multidisciplinary team in our Institutes and Vet School with expertise in veterinary medicine, disease epidemiology and mathematical modelling were commissioned to address this challenge. Led by Prof Rowland Kao in our Institute the team developed and test a revised surveillance model based on how likely a farm holding is to become infected, and how likely that infection is to be noticed at the slaughterhouse. For example, higher-risk holding include those that slaughter fewer than a quarter of their herd per year, and those that import cattle from high-bTB incidence areas in England, Wales or Ireland.

The Glasgow team worked with the Animal Health and Welfare Veterinary Laboratory Agency, the Chief Veterinary Officer for Scotland and the Scottish Government to help develop the research findings into a framework that was practical for implementation. The final form of the model was accepted in 2011 and has been in place since 2012. The rapid success of the ground-breaking Scottish research-led bTB policy development has been highlighted by the Civil Service as best practice open policy making.

As a result of this policy change more than 30% of Scottish herds became exempt from routine testing, resulting in savings to the Scottish Government of £150,000 per year. The reduction in bTB testing from the revised policy has also translated to an estimated saving to the farming industry of £100,000 associated with the loss of productivity during testing.

The team are currently developing risk-based models for use beyond Scotland; in 2012, the UK Department for the Environment, Farming & Rural Affairs (DEFRA) commissioned the Glasgow team to produce a model of risk-based bTB surveillance in England and Wales. Likewise, work is also underway for the Channel Island states of Jersey and Guernsey.

First published: 11 July 2014