May 20, 2025

expert reaction to an atypical case of BSE detected on a farm in Essex

Scientists comment on an atypical case of BSE (Bovine Spongiform Encephalopathy) detected on a farm in Essex. 

Prof Ian Jones, Professor of Virology, University of Reading, said:

“The focus in this news release should be the word “atypical”, in other words this is not a case that signals the BSE of the 1980s has returned, but a rare incident not dissimilar to the rare cases of Creutzfeldt–Jakob disease in the human population. BSE is part of a group of diseases known as protein folding disorders and occurs naturally at very low levels. Only if material from a BSE case was to be recycled through a herd would there be any risk of higher numbers. In this case the animal has been destroyed so that particular risk, and any concern about onward transmission, has been entirely removed. 

Dr Barry Bradford, Lecturer, Mucosal Host Pathogen Interactions & Prion Research and Neuropathology Groups, The Roslin Institute, University of Edinburgh, said:

What is an atypical case of BSE, how often do they occur, and how do they differ from typical BSE cases?

“Atypical BSE is a form of prion disease that occurs spontaneously in elderly cattle. Similar to sporadic Creutzfeldt-Jakobs disease in humans which occurs with an incidence of around 1 case per million of the population and then only in people aged at least over 40 years old and more commonly over 60 years old. There is no known cause and both conditions display a forebrain dominant targeting of pathological changes which spread backwards through the brain. This is in contrast to infectious prion diseases such as classical BSE, typically acquired through exposure of contaminated food and affects younger cattle. Infectious prion disease leave a tell-tale trace through the gut,  immune organs, nervous connections, and ultimately it’s final destination spreading from the spinal cord forwards through the brain leaving much of this material infectious in its wake. Atypical or sporadic prion diseases rarely show evidence of prions outside of the brain. Experimental transmission to laboratory mice reveals classical BSE is highly infectious whilst atypical forms are difficult to transmit unless very specific conditions are met.

Where could this case of BSE have originated from/how was it detected?

“Sporadic/atypical cases are thought to arise naturally. Prions are a misfolded form of a host cellular protein normally present at high levels in the brain. Infectious prions are capable of inducing the refolding of the benign host protein into the infectious form very efficiently. It is hypothesized that chance misfolding events may occur naturally and eventually may overcome the host cells protein quality control mechanisms especially if these have deteriorated with age for example.

“This case will have been detected by the routine screening for BSE setup following the BSE epidemic. Cases may be identified by their clinical symptoms of prion disease detected by stockmen, farmers or veterinarians. Suspect cases are subject to testing for abnormal prion proteins. These tests may also highlight biochemical differences between atypical and classical prions such as the relative size of the misfolded protein, structural differences or as mentioned above relative presence or absence in specific brain areas. These methods are effective at correctly identifying classical vs atypical cases.

Should we be concerned that more cases will crop up?

“No, it is likely with the size of UK cattle population and our effective screening and control measures that further cases will be detected with a similar low incidence in aged cattle similar to sCJD incidence in humans. There is no evidence that atypical BSE is infectious or will spread within herds. What is important is that current effective surveillance continues to ensure that any future BSE cases are identified and dealt with appropriately. We still don’t know the exact source of classical BSE which resulted in the UK epidemic and one possibility is that it arose spontaneously in cattle similar to this case. Whilst the conditions that led to the BSE epidemic have been removed (i.e. recycling of animal protein via meat and bone meal) there are other forms of prion disease such as Chronic Wasting disease in deer that are naturally highly infectious within herds as well as spread via environmental contamination with prions. Therefore continued vigilance regarding prion diseases is imperative.

Do these cases pose a risk to human health?

“Due to the rarity of these cases and effective surveillance it is unlikely that atypical BSE poses a direct risk to human health. Atypical BSE is not considered infectious. Identified cases do not enter the food chain. Current legislation such as the bovine offal order also require removal of all high risk materials such as brain from all cattle entering the human and animal food chains.

How are these cases handed and what do we prevent more in the future?

“Effective surveillance, reporting and research should continue as it is impossible to prevent future (though) rare occurrences of spontaneous prion disease.”

Prof Neil Mabbott, Personal Chair in Immunopathology and Head of Immunology Division, The Roslin Institute & Royal (Dick) School of Veterinary Sciences, University of Edinburgh, said:

“Atypical BSE (bovine spongiform encephalopathy) is a rare disease of cattle.  The disease is considered to occur sporadically and it is not acquired between cattle as an infection.  Atypical BSE differs from the classical BSE which caused the outbreak in the UK cattle herd in the 1980s and 1990s.  Classical BSE was considered by scientists to be spread amongst cattle through use of feed BSE-contaminated (meat and bone meal), and is estimated to have caused infection in up to half a million cattle during that period. 

“Very occasionally, rare atypical cases of BSE are sporadically detected in cattle, but these are considered non-contagious and are not linked to an infectious origin.  Four cases of atypical BSE have been detected in the UK in the past ten years.  This current case was detected through the routine surveillance and testing brain tissues from fallen stock animals. 

“The detection of this isolated case of atypical BSE shows that the UK’s surveillance programme is working well. There is no risk to the public, as the animal’s carcass will have been destroyed and no tissues will have entered the food chain. 

“BSE is a devastating neurological disease in cattle affecting the brain, spinal cord and some other organs.  Control measures remain in place to exclude these organs from the food chain to prevent the spread of BSE amongst cattle and to humans.  A measure of their success, is that there have been no cases of variant CJD (linked to consumption of BSE infected food) in people born after these controls were put in place in the UK in the 1990s.”

Declared interests

Dr Barry Bradford: Current COI “Lecturer at The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh. Funded by UKRI via BBSRC. Member of the British Neuroscience Association. Member and local representative for Prospect trade union. Reviewer Board member for International Journal of Molecular Sciences since 2021. Ad-hoc reviewer for numerous scientific journals.” Historic COI “Previously employed at The Institute for Animal Health by BBSRC. Previously part-funded by grants from Medical Research Council, Department of Health, Department for Environment, Food and Rural Affairs & Ministry for Agriculture Fisheries and Food. Member of the Society for Neuroscience/ Member of the British Society for Immunology. Member of the European Macrophage and Dendritic cell Society”

Prof Ian Jones: “I state no conflicts”

Prof Neil Mabbott: “I have no conflicts of interest to declare”