Brief overview
- Symptoms: Mental symptoms such as depression, apathy, rapidly progressing dementia, uncoordinated movements and muscle twitching, impaired sensation, balance and vision, stiff muscles
- Causes: Sporadic form (for no apparent reason), genetic cause, transmission through medical interventions (iatrogenic form), through consumption of infected food or blood transfusion (new form of vCJD), triggered by misfolded proteins (prions), which are deposited primarily in nerve cells, brain loosens up like a sponge
- Prevention: Avoid beef products made from nervous tissue, such as bovine brain, there is currently no vaccination against the disease, new hygiene regulations, such as in the processing of meat, during medical procedures and blood transfusions, minimize the risk of transmission
- Examinations: Checking coordination and reflexes, examination of cerebrospinal fluid (CSF) and blood, measurement of brain waves (EEG), imaging procedures (MRI), reliable confirmation after death by autopsy
- Treatment: Currently no treatment available, anticonvulsants (such as clonazepam or valproic acid) help against muscle twitching, antidepressants for depression, neuroleptics for hallucinations and restlessness
What is Creutzfeldt-Jakob disease?
Creutzfeldt-Jakob disease was first described in 1920 by the neurologists Creutzfeld and Jakob. It is one of the so-called transmissible, spongiform brain diseases (transmissible spongiform encephalopathies, TSEs). In these diseases, the brain tissue loosens up like a sponge and the brain gradually loses its function.
Creutzfeldt-Jakob disease occurs in various forms. These include
- Sporadic CJD: develops spontaneously for no apparent reason, is most common with 80 to 90 percent of cases, mostly affects people over 59 years of age
- Familial CJD: Genetically determined, usually becomes apparent around the age of 50
- Iatrogenic CJD: Transmission via diseased tissue during medical procedures, indirectly from person to person
- Variant CJD (vCJD): Transmission through consumption of infected food (such as meat from contaminated cattle or sheep) or via blood transfusion, average age less than 30 years
Transmissible spongiform encephalopathies are not only known in humans, but also in the animal kingdom. What they have in common is that they easily cross species boundaries, for example from sheep to cattle or from cattle to humans. The TSE “scrapie” in sheep has been known for around 200 years.
In Germany, around 80 to 120 people contract the sporadic form every year. This number has remained constant for years and is easy to determine, as doctors are required to report both cases of Creutzfeldt-Jacob disease and deaths to the health authorities. This does not include familial cases of CJD. No cases of the transmitted form, vCJD, have been reported in Germany up to and including 2021.
What are the symptoms?
Creutzfeldt-Jakob disease manifests itself in a so-called encephalopathy – a collective term for diseases of the brain. It mainly manifests itself through the following symptoms
- Mental abnormalities: for example depression, hallucinations, delusions, apathy, personality changes
- Rapidly progressing dementia with confusion, altered perception, concentration disorders
- Uncoordinated movements (ataxia)
- Involuntary muscle twitching (myoclonus)
- Sensory disturbances
- Balance disorders
- Uncontrollable muscle movements (chorea)
- Muscle stiffness (rigor)
- Visual disturbances
In the sporadic form, the most important symptom is dementia. In the final stage, the patient is motionless and apathetic.
In the transferred new variant vCJD, the mental abnormalities initially predominate. Dementia and disturbed, uncontrolled movements only occur later in the course of the disease.
Infection with Creutzfeldt-Jakob disease occurs in various ways. Iatrogenic transmission means that the infection was “caused by a doctor”. For example, transmission is possible during operations through contaminated neurosurgical instruments or blood transfusions. Other examples include a corneal transplant on the eye or a transplant of hard meninges (dura mater) on the condition that the donor suffered from Creutzfeldt-Jakob disease.
In the past, growth hormones from the pituitary gland of cadavers were used for therapy. Here, too, the operated patients were infected with Creutzfeldt-Jakob disease if the donors were ill.
Another form of transmission is oral ingestion of the pathogens. A few years ago, tribes in New Guinea still had the custom of ritually eating the brains of the dead. As a result, the disease (Kuru disease) spread rapidly there. The new variant of Creutzfeldt-Jakob disease is also a transmitted form. The cause is most likely beef contaminated with BSE pathogens that was eaten by patients.
Prions as a trigger
Scientists suspect that prions are created when a normal protein is misfolded and takes on a new structure. This protein in turn causes other proteins to also form faulty structures. In this way, many misfolded proteins accumulate in the body and are mainly deposited in nerve cells. The nerve cells are damaged and die, resulting in a sponge-like loosening of the brain.
How do prions develop?
Different types of altered prions are responsible for the development of Creutzfeldt-Jakob disease. In the case of sporadic CJD, nothing is yet known about the exact mechanism by which the prions develop.
Familial Creutzfeldt-Jakob disease is caused by defective genetic information. A mutation in the genetic material causes proteins to assemble incorrectly, resulting in prions. To date, over 30 different mutations are known and all are based on autosomal dominant inheritance. This means that this genetic information prevails over another and only one parent has to carry the faulty gene for the child to also develop the disease.
Are you infected when you are around people with the disease?
Creutzfeldt-Jakob disease: BSE
You can read everything you need to know about bovine spongiform encephalopathy in the article BSE.
Is preventive protection possible?
To protect yourself from Creutzfeldt-Jakob disease, you should avoid beef products made from nervous tissue, such as bovine brains. In addition, the feeding of animal meal to livestock species has been banned in order to prevent risk material from entering the human food chain as far as possible. Milk and dairy products are risk-free.
Since the outbreak of the BSE epidemic in the 1990s, there has been a BSE test for slaughtered cattle in Germany. Since 2015, this test has been abolished for healthy cattle. There is currently no vaccination against the disease.
Hygiene regulations
In order to minimize transmission during medical procedures, the Robert Koch Institute developed recommendations for the disinfection and sterilization of surgical instruments in suspected CJD cases and for patient care back in 1996 and 1998. There are also extensive precautionary measures to prevent the transmission of vCJD through blood and blood products. Among other things, people who have spent more than six months in the UK between 1980 and 1996 or who have received a blood transfusion or operation there since 1980 are excluded from donating blood.
The diagnosis of Creutzfeldt-Jakob disease is made by the doctor primarily on the basis of clinical symptoms. Before the physical examination, the doctor will ask you the following questions, among others, to record your medical history:
- What day is it today?
- Where are you?
- Are you happy?
- Did a relative of yours suffer from Creutzfeldt-Jakob disease?
- Have you had a corneal transplant?
Physical examination
Your doctor will then examine you physically and test the functioning of your nervous system. This includes coordination exercises or strength measurements as well as checking reflexes and the sensation of touch.
Examination of the cerebrospinal fluid
Nerve fluid (cerebrospinal fluid) is often obtained using a lumbar puncture. This flows around the brain and spinal cord and sometimes contains indications of possible causes of illness. Under local anesthesia, the doctor inserts a cannula into the lower back of the seated patient and pushes it forward to the so-called spinal canal, in which the spinal cord is surrounded by cerebrospinal fluid. If the patient suffers from Creutzfeldt-Jakob disease, increased concentrations of certain proteins such as the proteins “14-3-3” or “tau” are found in many cases. This is rarely the case with the transmitted variant vCJD.
Electroencephalography (EEG)
The doctor also uses electroencephalography (EEG) to record brain waves. To do this, he attaches electrodes to the patient’s head. A device records the electrical activity in the brain. In Creutzfeldt-Jakob disease, specific changes appear in the EEG from around twelve weeks after the onset of the disease, which sometimes disappear again as the disease progresses. These changes rarely occur in vCJD.
Magnetic resonance imaging (MRI)
Magnetic resonance imaging (MRI) can be used to visualize the spongy loosening and shrinkage of the brain. In addition, changes that indicate possible protein deposits can be seen in certain areas of the brain (often in the basal ganglia).
Blood tests
Blood tests are currently being developed to detect the sporadic and genetic forms of CJD. These new tests measure brain-specific neurofilaments (components of nerve cells) in the blood, which can be detected shortly before the onset of the disease.
Autopsy
What is the treatment?
There is currently no therapy that addresses the causes of Creutzfeldt-Jacob disease. The doctor therefore treats the individual symptoms as part of a so-called symptomatic therapy. Research is currently being carried out into appropriate medication to cure the disease.
So-called anticonvulsants help against muscle twitching. These drugs are also used in the treatment of seizures. In Creutzfeldt-Jakob disease, the active ingredients clonazepam and valproic acid are primarily used.
Antidepressants are also used for depression and neuroleptics for hallucinations and agitation.
How does the disease progress and what is the prognosis?
Creutzfeldt-Jakob disease cannot be cured and is always fatal after a short time. How long it takes for the disease to break out after infection (incubation period) has not yet been conclusively clarified. Doctors assume that it takes years to decades.
Patients with vCJD fall ill much earlier, before the age of 30. The new variant of Creutzfeldt-Jakob disease lasts longer and is fatal after around twelve to 14 months.