Variant CJD is a different disease from the common form, and the numbers are small. From 1996 to 2023, 233 deaths from it were reported worldwide. Most were in the United Kingdom, with smaller numbers in other European countries, Asia, Saudi Arabia, Canada and the United States.
Where did it come from?
It is linked to bovine spongiform encephalopathy, or BSE, a prion disease of cattle known as mad cow disease. The evidence for that link comes from both epidemiology and the laboratory, and confirmed cases of variant CJD are generally absent from countries where BSE was not present.
The link was identified in 1996. Controls on cattle and on the food chain in the UK followed, and the NHS describes those controls as having been effective. Cattle feeding practices that spread BSE have since changed.
The time between exposure and the first symptoms is long, probably around ten years and sometimes more. That is why cases continued to appear for years after the food controls came in.
Who does it affect, and what does it look like?
It has affected younger people than other forms of CJD. The median age at death is 28 years, against 68 years for the classic form.
It usually begins with psychological symptoms: severe low mood, anxiety, irritability, difficulty sleeping, or withdrawal from family and friends. Painful or unpleasant sensations in the limbs are a prominent early feature. Neurological symptoms such as unsteadiness, jerky movements, memory problems and difficulty with vision usually follow around four months later. The illness lasts longer than classic CJD, with a median of 13 to 14 months. Our symptoms page goes through these in order.
Can it be passed on?
It is not caught through everyday contact, and it is not inherited.
The prion has been passed on through blood transfusion, which the NHS reports has happened five times in the UK. Blood services in several countries changed their donor rules because of this. If you have been told you are at increased risk through a transfusion or a medical procedure, the team that told you is the right one to ask what it means for you.
How is it diagnosed and treated?
There is no single test that proves it. Doctors use the pattern and timing of symptoms together with an MRI scan, where a bright signal in a part of the brain called the pulvinar is seen in more than three quarters of cases and is a strong pointer. A certain answer comes from examining brain tissue. How it is diagnosed explains the steps.
No treatment stops the disease. Care is aimed at comfort, and symptoms including pain, low mood, poor sleep and jerky movements can be treated. A palliative care team can be involved early. What to expect sets out the practical side.
Who should I ask about my own situation?
This page cannot tell you what is happening to a particular person, or what any past exposure means for you. A neurologist is the right person for symptoms and test results, and in the United Kingdom suspected prion disease is referred to the National Prion Clinic.
A clinical account is in variant CJD: more detail, the science is summarised on our research page, and studies open to join are listed under current trials. The other conditions in this group, including variably protease-sensitive prionopathy, are on our diseases page.