Most people arrive at this page because of the older name, mad cow disease, and because they want to know whether something they ate years ago can still harm them.
What BSE is
A fatal brain disease of cattle, caused by a prion. Affected cattle usually show no signs until they are about four or five years old, and then changes come on slowly over weeks or months: changes in behaviour, nervousness, weak or high-stepping hind legs, difficulty getting up, tremors, weight or milk loss, and excessive licking of the nose.
The link to people
Eating food contaminated with BSE caused a human prion disease, variant CJD. That is why rules exist to keep particular cattle tissues, called specified risk material, out of the food chain, and why cattle that may have eaten the same feed as a case are removed.
Variant CJD has become rare. The 2026 review of human prion disease describes acquired forms, the group variant CJD belongs to, as exceedingly rare now, against about 85 percent of human cases being sporadic CJD, which has no known food or environmental cause. Variant CJD covers what is known about the human illness, including its very long incubation period.
If you are worried about meat you ate in the past, that worry is understandable and there is no test that can settle it. A neurologist is the person to talk to about symptoms, and I am worried about exposure covers what can and cannot be answered.
What happens now when a case is suspected
In Great Britain, BSE is a notifiable disease, which means a farmer or vet must report a suspected case immediately, and not reporting it is against the law. Reporting numbers are 03000 200 301 in England and 0300 303 8268 in Wales, and in Scotland the local Field Services Office.
An Animal and Plant Health Agency vet then visits and assesses the animal. If BSE is suspected, movement restrictions are placed on the animal and the herd, and the animal is either culled on the farm or taken to a laboratory, depending on its condition, and tested.
Cattle born in the same herd within a year either side of a case, or reared with it before both were a year old, are traced, restricted and culled, because they may have eaten the same feed. For a suspect female, offspring born up to two years before or after she showed signs are traced, and slaughtered if BSE is confirmed. Owners can appeal a cull decision with feed control records within 21 days, and compensation is paid for animals culled to control BSE.
The UK’s current status
The World Organisation for Animal Health and the European Union recognise the UK as negligible risk, the lowest BSE risk category.
That category is about cattle and controls rather than about any individual’s health. It is the shorthand answer to the question of whether BSE is still a live problem in British herds.
Other animal prion diseases
Scrapie affects sheep and goats, and chronic wasting disease affects deer, elk and moose. They are covered on scrapie and chronic wasting disease, and food and travel questions on safety.
For the research literature on cattle BSE, including the atypical forms found through routine testing of older animals, see BSE in the research section. The animal prion diseases hub collects these pages.