Insights aim to accelerate eradication of BSE

Cases of the fatal livestock disease bovine spongiform encephalopathy (BSE) peaked in the late 20th century, in an outbreak that led to the slaughter of an estimated four million cattle in the UK. 

Transmission of the disease occurred through inclusion of contaminated animal protein in livestock feed. 

The infection results in build-up of misfolded protein, or prions, in the brains of cattle, leading to nervous or aggressive behaviour and difficulties in walking and standing, hence the nickname of mad cow disease. 

Most seriously, BSE also spread to humans, resulting in more than 200 deaths from variant Creutzfeldt-Jakob disease (vCJD) to date.

A ban on the use of processed animal protein in livestock feed was introduced, leading to a near-cessation of disease in recent years.

However, occasional contemporary cases still occur, including a recent case reported in August 2026 in Dumfries and Galloway, Scotland.

A costly, extensive programme of surveillance and control measures remains in place throughout Europe to identify and investigate these incidences, and ensure that affected cattle do not enter the human food chain. 

Greater understanding of the origins of disease, and the cause of modern-day cases, could enable progress towards its eradication, and inform targeted strategies for disease detection and mitigation of risks of similar livestock disease outbreaks in future. 

Towards BSE eradication 

A new programme of research seeks to understand the origins of contemporary BSE cases, in order to develop strategies and tools to assist disease eradication, and help to prevent future outbreaks of prion diseases in livestock. 

With €1.25m funding provided through the European Partnership on Animal Health and Welfare (EUPAHW), the programme is led by Dr Fiona Houston of the Roslin Institute and involves scientists from the Friedrich-Loffler Institute in Germany, National Research Institute for Agriculture, Food and Environment (INRAE) and the Pasteur Institute in France, and the UK Animal and Plant Health Agency.

“We still don’t know where BSE came from,” explains Dr Houston. “The original BSE outbreak was linked to contaminated cattle feed, which could have included products from sheep or cattle with undetected prion disease. However, despite a decades-long ban on feeding animal protein to livestock, cases of BSE still occur and their causation is difficult to explain.”

The EUPAHW-funded research consortium will focus on four aspects of the disease. Scientists will seek to better understand the genetic basis of susceptibility to BSE, pick apart the possible origins of contemporary BSE cases, and develop ways to detect and mitigate contamination in livestock environments.

Genetic susceptibility

Scientists will seek to identify genes that may influence susceptibility to BSE.

To do this, they will examine the entire genetic code, or whole genome sequence, from cases of BSE in animals born after the ban on feeding animal protein, in comparison with DNA from healthy cattle, to identify genetic variants that may be associated with disease. 

In parallel, studies using brain material from genetically diverse laboratory mice will aim to pinpoint genes and variants linked to efficient replication of BSE prions.

Combining results from these studies may aid identification of specific genes linked to disease, allowing screening and removal of livestock at greater risk of developing BSE.

Infection origins

BSE may have originated from other animal prion diseases, such as sheep scrapie, or atypical forms of scrapie and BSE that occur spontaneously in a small proportion of older animals.

Researchers will adapt highly sensitive existing tests for prion detection, to allow accurate identification and discrimination between these different prion diseases. 

These methods will be applied to BSE cases from different stages of the epidemic - early, at its peak, and after the feed ban – with the aim of identifying disease-specific signatures that may give clues to the original source of infection.

The team will use two established technologies to that can amplify minute quantities of prions in samples –protein misfolding cyclic amplification (PMCA) – and real-time quaking induced conversion (RT-QuIC).

This work can help to clarify how BSE emerged and thus inform control measures most likely to prevent recurrence of the disease. The methods developed could be used in emerging animal prion diseases to enable rapid assessment of risks to human health

Managing environmental contamination

Prions are very resistant to disinfection, and can persist in contaminated environments for years. Although BSE-infected cattle are not thought to shed large quantities of infectious prions, it remains possible that some BSE cases originate from environmental sources.

To investigate this possibility, Roslin scientists will lead work to develop ways of detecting BSE in environmental samples such as soil, and swabs from farm building or equipment surfaces. 

Methods will be based on PMCA and/or RT-QuIC, adopting technical improvements and the ability to discriminate between different prion diseases developed from the work on infection origins described above.

Detection of BSE in relevant environmental samples could help in tracing sources of infection for post-feed ban cases and monitoring effectiveness of decontamination procedures. 

The few methods available for disinfection of prion-contaminated environments and equipment are harsh and potentially hazardous to human health. Therefore, the team also aims to test alternative, less damaging disinfectants suitable for use in farm environments, to establish their efficacy in removal or inactivation of BSE. 

Identification of less hazardous and environmentally benign disinfectants compared with current approaches would increase options for disease control, and reduce the health and financial burdens on farmers. 

Ensuring disease safeguards

The emergence of BSE as a novel zoonotic prion disease of cattle had an enormous influence on animal and public health policies worldwide, with major impacts on agriculture, international trade, biopharmaceuticals and healthcare. 

With incidence of BSE at very low levels, there is increasing pressure to relax costly control measures aimed at reducing transmission risks. 

To manage this safely and prevent future re-emergence of BSE, it is important that the disease is completely eradicated and/or that there are systems and techniques in place to enable early detection of recurrent cases. 

In this project, the collaborating team aims to accelerate progress towards eradication of BSE, addressing fundamental scientific uncertainties regarding the unexplained persistence of classical BSE, and developing novel technologies that can improve disease monitoring and control both now and in future.

Related links

Media coverage: Mad cow disease case confirmed at farm in Dumfries and Galloway.