Medical name for mad cow disease. Creutzfeldt-Jakob Disease (CJD): Symptoms, Causes, and Types Explained
What is Creutzfeldt-Jakob disease. What are the main symptoms of CJD. How is CJD caused. What are the different types of CJD. How is CJD treated. Is there a compensation scheme for variant CJD.
Understanding Creutzfeldt-Jakob Disease: A Rare and Fatal Brain Condition
Creutzfeldt-Jakob disease (CJD) is a rare and devastating neurological disorder that rapidly affects brain function. This condition, which belongs to a group of diseases known as transmissible spongiform encephalopathies (TSEs), is characterized by the accumulation of abnormal prion proteins in the brain. These prions cause irreversible damage to nerve cells, leading to a rapid decline in cognitive and physical abilities.
CJD affects approximately one to two people per million annually in the United Kingdom. While it can occur at any age, it most commonly affects individuals between 45 and 75 years old. The disease progresses quickly, with most patients succumbing to complications within a year of symptom onset.
How does CJD differ from other neurodegenerative diseases?
Unlike many other neurodegenerative diseases, CJD is caused by prions rather than genetic mutations or environmental factors. Prions are misfolded proteins that can trigger a chain reaction, causing other normal proteins in the brain to misfold and accumulate. This process leads to rapid and severe brain damage, distinguishing CJD from conditions like Alzheimer’s or Parkinson’s disease, which typically progress more slowly.
Recognizing the Symptoms of Creutzfeldt-Jakob Disease
The symptoms of CJD can be diverse and may initially mimic other neurological conditions. However, the rapid progression of these symptoms is a hallmark of the disease. Early recognition is crucial for proper management and care.
- Loss of intellect and memory
- Personality changes
- Impaired balance and coordination
- Slurred speech
- Vision problems, potentially leading to blindness
- Abnormal jerking movements
- Progressive loss of brain function and mobility
As the disease advances, patients often experience a rapid decline in cognitive abilities and motor functions. This deterioration can lead to a state of akinetic mutism, where the individual becomes unresponsive and unable to move or speak.
Why do CJD symptoms progress so rapidly?
The swift progression of CJD symptoms is due to the unique nature of prion diseases. Once prions begin to accumulate in the brain, they trigger a cascade of protein misfolding that spreads quickly throughout neural tissue. This process leads to widespread neuronal death and brain damage at a much faster rate than other neurodegenerative conditions.
The Enigmatic Causes of Creutzfeldt-Jakob Disease
CJD is caused by the accumulation of abnormal prion proteins in the brain. These prions are misfolded versions of a normal protein found in the central nervous system. Unlike other infectious agents such as viruses or bacteria, prions are not destroyed by extreme heat, radiation, or standard sterilization procedures.
The exact mechanism that triggers the initial protein misfolding in most cases of CJD remains a mystery. However, researchers have identified several risk factors and potential causes for different types of the disease.
Are prions resistant to conventional sterilization methods?
Yes, prions exhibit remarkable resistance to standard decontamination procedures. They can withstand temperatures and radiation levels that would typically destroy other pathogens. This resistance poses significant challenges in medical settings, particularly in preventing iatrogenic transmission of CJD through surgical instruments or other medical procedures.
Exploring the Four Main Types of Creutzfeldt-Jakob Disease
CJD is classified into four main types, each with distinct characteristics and origins. Understanding these types is crucial for proper diagnosis, management, and potential prevention strategies.
1. Sporadic CJD (sCJD)
Sporadic CJD is the most common form, accounting for about 85% of all cases. It occurs randomly and affects individuals with no known risk factors or genetic predisposition. The exact cause of sCJD is unknown, but it’s believed to result from spontaneous misfolding of prion proteins in the brain.
2. Variant CJD (vCJD)
Variant CJD is associated with the consumption of beef products contaminated with bovine spongiform encephalopathy (BSE), commonly known as “mad cow disease.” This form of CJD gained significant attention in the 1990s due to an outbreak in the United Kingdom. Strict food safety measures have since dramatically reduced the incidence of vCJD.
3. Familial or Inherited CJD
This rare form of CJD is caused by genetic mutations in the prion protein gene (PRNP). Individuals with these mutations inherit an increased risk of developing CJD. Familial CJD accounts for about 10-15% of all CJD cases.
4. Iatrogenic CJD
Iatrogenic CJD occurs when the disease is accidentally transmitted through medical procedures. Historical cases have been linked to contaminated surgical instruments, transplanted corneas or dura mater grafts, and the use of human-derived growth hormones. Improved safety protocols have made iatrogenic CJD extremely rare in recent years.
The Challenge of Treating Creutzfeldt-Jakob Disease
Currently, there is no cure for CJD, and treatment focuses on managing symptoms and providing supportive care. The rapid progression of the disease and the unique nature of prion infections make developing effective treatments extremely challenging.
What are the primary goals of CJD treatment?
The main objectives of CJD treatment are:
- Alleviating symptoms and improving quality of life
- Managing complications such as infections
- Providing emotional support to patients and their families
- Ensuring comfort and dignity in the later stages of the disease
Medical interventions may include:
- Antidepressants to address anxiety and depression
- Painkillers to manage discomfort
- Anticonvulsants to control seizures
- Nursing care and assistance with feeding and hydration
While these measures can help improve the patient’s quality of life, they do not alter the course of the disease or prevent its progression. Research into potential treatments for CJD is ongoing, with a focus on understanding prion biology and developing methods to prevent or reverse protein misfolding.
Preventing Creutzfeldt-Jakob Disease: Challenges and Strategies
Preventing CJD presents unique challenges due to the nature of prion diseases and the various modes of transmission. However, several strategies have been implemented to reduce the risk of CJD, particularly for variant and iatrogenic forms.
How effective have food safety measures been in preventing vCJD?
The implementation of strict food safety controls has been highly effective in preventing variant CJD. These measures include:
- Banning the use of meat and bone meal in animal feed
- Removing specified risk materials (such as brain and spinal cord) from the food chain
- Enhancing surveillance and testing of cattle for BSE
- Restricting the importation of beef products from countries with BSE outbreaks
As a result of these measures, the incidence of vCJD has declined dramatically. In 2020, there were no recorded deaths from variant CJD in the UK, compared to the peak of the outbreak in the late 1990s and early 2000s.
What steps are taken to prevent iatrogenic CJD?
To minimize the risk of iatrogenic CJD, healthcare systems have implemented various precautions:
- Using synthetic growth hormones instead of those derived from human pituitary glands
- Improving sterilization techniques for surgical instruments, particularly those used in neurosurgery
- Implementing strict screening protocols for tissue and organ donors
- Developing single-use instruments for certain high-risk procedures
- Enhancing surveillance and reporting systems for CJD cases
These measures have significantly reduced the occurrence of iatrogenic CJD, with only rare cases reported in recent years.
The Variant CJD Compensation Scheme: Supporting Affected Individuals and Families
In recognition of the devastating impact of variant CJD and its link to BSE-contaminated beef products, the UK government established a compensation scheme for affected individuals and their families. This scheme aims to provide financial support and acknowledge the unique circumstances surrounding vCJD cases.
Who is eligible for the vCJD compensation scheme?
The compensation scheme is available to:
- Individuals diagnosed with vCJD
- Family members of those who have died from vCJD
- Individuals who have received blood products from donors who later developed vCJD
The scheme provides various forms of financial support, including lump sum payments, ongoing care costs, and compensation for loss of earnings. While no amount of money can fully compensate for the impact of vCJD, the scheme aims to alleviate some of the financial burdens associated with the disease.
How has the compensation scheme evolved since its inception?
Since its establishment in October 2001, the vCJD compensation scheme has undergone several revisions to better address the needs of affected individuals and families. These changes have included:
- Expanding eligibility criteria to include more potentially affected individuals
- Increasing the maximum available compensation amounts
- Streamlining the application process to reduce delays in receiving support
- Providing additional resources for ongoing care and support services
The scheme continues to be reviewed and updated to ensure it remains responsive to the evolving understanding of vCJD and its long-term impacts.
Ongoing Research and Future Directions in CJD Management
Despite the challenges posed by CJD, researchers continue to make progress in understanding the disease and developing potential interventions. Current areas of focus include:
What are the most promising avenues for CJD treatment research?
Several promising research directions are being pursued:
- Developing compounds that can stabilize normal prion proteins and prevent misfolding
- Exploring immunotherapy approaches to target and clear abnormal prion proteins
- Investigating gene therapy techniques to modify or silence the prion protein gene
- Enhancing early diagnostic methods, including blood tests and imaging techniques
- Studying the potential of stem cell therapies to replace damaged neurons
While these research areas show promise, developing effective treatments for CJD remains a significant challenge due to the rapid progression of the disease and the unique properties of prions.
How might advances in prion research impact other neurodegenerative diseases?
Insights gained from CJD research may have broader implications for understanding and treating other neurodegenerative conditions. Some potential applications include:
- Improving our understanding of protein misfolding in diseases like Alzheimer’s and Parkinson’s
- Developing new approaches to prevent or reverse protein aggregation in the brain
- Enhancing diagnostic techniques for early detection of neurodegenerative processes
- Identifying novel therapeutic targets for a range of brain disorders
As research into CJD and other prion diseases continues, it may provide valuable insights that could benefit the broader field of neurodegenerative disease research and treatment.
Creutzfeldt-Jakob disease – NHS
Creutzfeldt-Jakob disease (CJD) is a rare and fatal condition that affects the brain. It causes brain damage that worsens rapidly over time.
Symptoms of CJD
Symptoms of CJD include:
- loss of intellect and memory
- changes in personality
- loss of balance and co-ordination
- slurred speech
- vision problems and blindness
- abnormal jerking movements
- progressive loss of brain function and mobility
Most people with CJD will die within a year of the symptoms starting, usually from infection.
This is because the immobility caused by CJD can make people with the condition vulnerable to infection.
Read more about the symptoms of Creutzfeldt-Jakob disease and diagnosing Creutzfeldt-Jakob disease.
What causes CJD?
CJD appears to be caused by an abnormal infectious protein called a prion. These prions accumulate at high levels in the brain and cause irreversible damage to nerve cells.
While the abnormal prions are technically infectious, they’re very different from viruses and bacteria.
For example, prions aren’t destroyed by the extremes of heat and radiation used to kill bacteria and viruses, and antibiotics or antiviral medicines have no effect on them.
Read more about the causes of Creutzfeldt-Jakob disease.
Types of CJD
There are 4 main types of CJD.
Sporadic CJD
Sporadic CJD is the most common type.
The precise cause of sporadic CJD is unclear, but it’s been suggested that a normal brain protein changes abnormally (“misfolds”) and turns into a prion.
Most cases of sporadic CJD occur in adults aged between 45 and 75. On average, symptoms develop between the ages of 60 and 65.
Despite being the most common type of CJD, sporadic CJD is still very rare, affecting only 1 or 2 people in every million each year in the UK.
In 2020, there were 131 recorded deaths from sporadic CJD in the UK.
Variant CJD
Variant CJD (vCJD) is likely to be caused by consuming meat from a cow that had bovine spongiform encephalopathy (BSE, or “mad cow” disease), a similar prion disease to CJD.
Since the link between variant CJD and BSE was discovered in 1996, strict controls have proved very effective in preventing meat from infected cattle entering the food chain.
See preventing Creutzfeldt-Jakob disease for more information.
But the average time it takes for the symptoms of variant CJD to occur after initial infection (the incubation period) is still unclear.
The incubation period could be very long (more than 10 years) in some people, so those exposed to infected meat before the food controls were introduced can still develop variant CJD.
The prion that causes variant CJD can also be transmitted by blood transfusion, although this has only happened 5 times in the UK.
In 2020, there were no recorded deaths from variant CJD in the UK.
Familial or inherited CJD
Familial CJD is a very rare genetic condition where one of the genes a person inherits from their parent (the prion protein gene) carries a mutation that causes prions to form in their brain during adulthood, triggering the symptoms of CJD.
It affects about 1 in every 9 million people in the UK.
The symptoms of familial CJD usually first develop in people when they’re in their early 50s.
In 2020, there were 6 deaths from familial CJD and similar inherited prion diseases in the UK.
Iatrogenic CJD
Iatrogenic CJD is where the infection is accidentally spread from someone with CJD through medical or surgical treatment.
For example, a common cause of iatrogenic CJD in the past was growth hormone treatment using human pituitary growth hormones extracted from deceased individuals, some of whom were infected with CJD.
Synthetic versions of human growth hormone have been used since 1985, so this is no longer a risk.
Iatrogenic CJD can also occur if instruments used during brain surgery on a person with CJD aren’t properly cleaned between each surgical procedure and are reused on another person.
But increased awareness of these risks means iatrogenic CJD is now very rare.
In 2020, there was 1 death from iatrogenic CJD in the UK caused by receiving human growth hormone before 1985.
How CJD is treated
There’s currently no cure for CJD, so treatment aims to relieve symptoms and make the affected person feel as comfortable as possible.
This can include using medicine such as antidepressants to help with anxiety and depression, and painkillers to relieve pain.
Some people will need nursing care and assistance with feeding.
Read more about treating Creutzfeldt-Jakob disease.
Variant CJD compensation scheme
In October 2001, the government announced a compensation scheme for UK victims of variant CJD.
The vCJD Trust assesses claims and pays compensation to victims and their families.
Page last reviewed: 07 September 2021
Next review due: 07 September 2024
USDA APHIS | Bovine Spongiform Encephalopathy (BSE)
Last Modified: May 30, 2023
Summary
Bovine Spongiform Encephalopathy (BSE), widely referred to as “mad cow disease,” is a chronic degenerative TSE disease affecting the central nervous system of cattle. It is caused by an abnormal prion protein. It has been identified in two forms: classical BSE (C-Type) and atypical BSE forms (L-type or H-type).
C-type BSE has been linked to variant Creutzfeldt-Jakob disease (vCJD) in humans, hence the zoonosis importance of the disease. C-type BSE in cattle results from the ingestion of cattle feed (i.e. meat-and-bone meal) containing the abnormal prion protein. Feeding mammalian protein to cattle have been prohibited in the U. S. since 1997. As a result of this control measure C-type BSE cases have not been diagnosed in the U.S., except for a C-type BSE case in 2003 where the cow originated from Canada.
The Atypical BSE forms, L- and H-type, occur spontaneously at very low levels in all cattle populations, particularly older cattle 8 years of age or older and does not appear to be associated with contaminated feed. Bioassay data support the hypotheses that these strains are biologically distinct from C-type BSE and might not pose a risk to humans. In 2015, the World Animal health Organization (OIE) excluded atypical BSE forms from the classical BSE general risk provisions.
In 2013, the OIE upgraded U.S. Status for BSE to negligible risk, the highest status available.
History
BSE was first diagnosed in 1986 in Great Britain. Since then, more than 185,000 cases have been confirmed worldwide. More than 95 percent of these have occurred in the United Kingdom, but the disease has also been confirmed in native-born cattle in the following countries: Austria, Belgium, Canada, the Czech Republic, Denmark, Finland, France, Germany, Greece, Ireland, Israel, Italy, Japan, Luxembourg, Liechtenstein, the Netherlands, Poland, Portugal, Slovakia, Slovenia, Spain, Switzerland, and the U. S.
Five cases of BSE have been identified in the U.S. The first case in 2003 was confirmed as C-type BSE and the subsequent four cases were confirmed as atypical BSE forms. The first case was detected in 2003 in Washington State in a 6 year-old dairy cow imported from Canada. The second, in 2005, was a 12 year-old beef cow in Texas. The third, in 2006, was a 10 year-old beef cow in Alabama. The fourth, in 2012, was a 10 year-old dairy cow in California. The fifth case, in 2017, was an 11 year-old beef cow in Alabama. As a result, U.S. beef exports dropped 80% after 2003 and have not yet fully recovered. It was not until May 2017 that China allowed U.S. beef exports to flow directly to the country since 2003 when the C-type BSE case was confirmed in U.S.
Clinical Course
Cattle affected by BSE experience progressive degeneration of the nervous system. Affected animals may display changes in temperament (nervousness or aggression), abnormal posture, incoordination and difficulty in rising, decreased milk production, or loss of condition without noticeable loss of appetite. There is no treatment or vaccine to prevent BSE. The incubation period is from 2 to 8 years. Following the onset of clinical signs, the animal’s condition deteriorates until it either dies or is destroyed. This process usually takes from 2 weeks to 6 months.
Etiologic Agent
and Tissue Distribution
The agent responsible for BSE has not been completely characterized. There are a variety of theories regarding the nature of the agent. The most widely accepted is that disease is caused by an abnormal prion protein that accumulates in the central nervous system and causes the normal cellular version of the protein to change shape such that it can no longer be degraded by the cell, causing the protein to accumulate and damage the cell.
The BSE agent is extremely resistant to heat and to normal sterilization processes. It also does not evoke any detectable immune response or inflammatory reaction in host animals. In cattle naturally infected with BSE, evidence of disease has been found only in brain tissue, in the spinal cord, and in the retina. In experimentally infected cattle, the distal ileum, bone marrow, dorsal root ganglion, and trigeminal ganglion from experimentally infected cattle were also found to be infective.
Transmission
BSE is not a contagious disease and therefore is not spread through casual contact between cattle or with other species. The primary source of C-type BSE infection in cattle is commercial feed contaminated with the infectious agent. Scientific evidence shows that feed contamination results from incorporating ingredients (for example, meat-and-bone meal) that contain protein derived from rendered infected cattle. Standard rendering processes do not completely inactivate the BSE agent. Therefore, rendered protein such as meat-and- bone meal derived from infected animals may contain the infectious agent. The preferred method for disposal of BSE-infected carcasses is alkaline digestion or complete, high- temperature incineration. Under no circumstances should BSE suspects be used for human or animal consumption.
Testing
Currently, there is no validated test to detect the disease in a live animal. BSE testing is done by examining the obex portion of the brain stem for the accumulation of abnormally folded prion protein. BSE screening is generally done by enzyme-linked immunosorbent assay (ELISA) on fresh tissue. BSE can be confirmed by immunohistochemistry or Western Blot. Histopathology may also be utilized to look for spongiform changes in brain stem tissue that are characteristic of the TSEs.
The accumulation of abnormal prion protein material and other changes in brain stem tissue that are diagnostic for BSE are not apparent in the early stages of the disease. Thus, the failure to detect BSE is not equivalent to a negative test or the absence of infectivity. Current testing methods are surveillance tools only. They are not intended to protect human health or animal health nor can they guarantee food safety.
Surveillance
BSE surveillance has been conducted in the U. S. since 1990. After the initial case of BSE was detected in the U.S. in late 2003, APHIS conducted a BSE Enhanced Surveillance Program from 2004 to 2006. This was a one-time intensive effort to detect BSE if present at a very low level and to provide information about prevalence. More than 830,000 animals were tested. Subsequent data analysis indicated that the prevalence of BSE in the U.S. was very low—less than one infected animal per million based on a population of 42 million adult cattle.
Beginning in 2006, the BSE Ongoing Surveillance Program was implemented. This program follows a stringent U.S. standard of detecting one case of BSE per one million adult cattle with 95% confidence. This standard far exceeds the current surveillance standards provided by the OIE for the U.S. under BSE negligible risk or Type B surveillance which is to detect one case of BSE per 50,000 adult cattle with 95% confidence. Both standards are based on a point system that reflects the likelihood of finding BSE. The BSE Ongoing Surveillance Program focuses on populations of cattle at higher risk for BSE, including those animals that are 12 months of age and older that display CNS signs and those over 30 months of age that are condemned on ante-mortem inspection at slaughter and thus are excluded from slaughter due to poor health status (non-ambulatory, unhealthy, or dead). From 2006 to 2015, the BSE Ongoing Surveillance Program tested approximately 40,000 samples per year. On 2015, the BSE sample collections were reduced to 25,000 per year. In the last 11 years the U.S. BSE sample collection resulted in point totals that far exceed both the OIE and U.S. requirements.
Eradication and
Control Efforts
Agricultural officials in the United Kingdom and other countries affected with BSE have taken actions to eradicate or control the disease. These entail prohibiting the inclusion of mammalian meat-and-bone meal in animal feed; prohibiting the use of specified risk materials or SRMs (those tissues, e. g., brain and spinal cord, known to have the highest infectivity) in food, feed, or other products; and destroying animals showing signs of BSE and other animals at high risk of developing the disease. As a result of these actions, most notably the imposition of feed bans, the rate of newly reported cases of BSE in the United Kingdom has greatly decreased.
In 1997, the U.S. Food and Drug Administration (FDA) implemented regulations that prohibit the feeding of most mammalian proteins to ruminants, including cattle. This feed ban is the most important measure to prevent the transmission of disease to cattle. In 2008, the ban was strengthened by prohibiting the inclusion of SRMs (brains and spinal cords from animals 30 months of age or older) in any animal feed. The 2008 rule also prohibits the use of entire carcass of cattle not inspected and passed for human consumption, unless the cattle are less than 30 months of age, or the brains and spinal cords have been removed.
Public Health
Significance
In March 1996, the United Kingdom’s Spongiform Encephalopathy Advisory Committee (SEAC) announced the identification of 10 cases of variant Creutzfeldt-Jakob disease (vCJD) in people. These cases had a characteristic clinical and pathological phenotype that differed from other routinely diagnosed cases of classic (sporadic) CJD. SEAC concluded, and scientific evidence later confirmed, that these cases were linked to exposure to C-type BSE before the feed bans were implemented. It is not known whether atypical forms of BSE (L- or H-type) are casually linked to forms of human prion diseases.
In the U.S., public or human health protective measures are maintained by both the Food Safety and Inspection Service (FSIS) and the FDA. The most important public health protective measure is the removal of SRMs from the human food supply. Other controls include banning nonambulatory disabled cattle from the human food chain; prohibiting air-injection stunning of slaughter cattle; requiring additional process controls in advanced meat-recovery systems; and forbidding the use of mechanically separated meat in human food. Additionally, protection from BSE and other disease is achieved through antemortem inspection of slaughter cattle and the exclusion from slaughter of animals with any clinical signs of neurological disease or other abnormalities.
Identifying
Affected Animals
The U.S. also maintains import regulations, consistent with the OIE guidelines for BSE, to prevent BSE from entering the US through imports. Beginning in 1989, APHIS prohibited the importation of ruminants and most ruminant products from countries that had identified BSE in native cattle or that were at risk for BSE.
An ongoing, comprehensive interagency surveillance program for BSE has been in place in the U.S. since 1990. APHIS also supports the FDA’s regulation prohibiting the use of most mammalian proteins in ruminant feed. Currently, USDA allows the importation of some animals and commodities under permit or by regulation from minimal BSE-risk countries.
Because of the clinical history that can be obtained, samples collected on the farm from cattle exhibiting symptoms of central nervous system disease are particularly valuable to the BSE Ongoing Surveillance Program efforts in the U.S. Accredited veterinarians with proper training can play a key role in the sampling of these animals and should contact their VS field office for more information. BSE is a reportable disease. Any suspicious cases should be reported to the APHIS – VS Area Offices or the State animal health official as a suspected foreign animal disease (FAD).
Protein history
What is senile dementia? Is it the price to pay for being unnatural
long life in modern civilization? Or sickness
Is Alzheimer’s as contagious as mad cow disease?
Professor Adriano Aguzzi is one of those people
whose work will someday help to shed light on these exciting
questions. The hero of the next issue of the program “Ideas that change the world”
(a joint project of the TV company “Obvious – incredible” and
channel “Russia 24”) – a world-class expert on prions,
as yet poorly understood infectious proteins that cause
irreversible degenerative changes in the brain. The scientist is sure that
observing the destructive mechanism of their action, people will someday
will surely discover the secret of intellectually productive
old age.
“Rita Levi-Montalcini, who died a year ago at the age of 103
years, was a brilliant scientist until the last days. When I’m with her
discussed science, she was 100 years old and as fresh as
you,” recalling a great neuroscientist colleague, the hero of “Ideas”
elegantly compliments his interlocutor, author and presenter
Evelina Zakamskaya. Michelangelo painted the Sistine
chapel when he was in his 60s. Astronaut John Glenn flew into
space at 77 years old. I think Alzheimer’s and prions
diseases are ailments, not just consequences
senile age,” says the scientist in the frame of “Ideas”.
Professor Adriano Aguzzi heads the Institute of Neuropathology at
the basis of the oldest and largest Swiss hospital –
University Hospital Zurich. Office of an authoritative scientist
turned out to be so ascetic and modest in area that for the record
interview our film crew had to choose a seat on the balcony
clinics. Scenic view: Lake Zurich, green slopes
surrounding mountains, one of the most cosmopolitan cities in the world.
“Science was global before the economy became global”
– our hero once said in an interview. And the professor himself
is the living embodiment of this idea: the Italian who
worked in Austria, Germany, USA and Switzerland; and the team
which he heads is also international.
Why is the brain “softened”?
The Swiss landscape is often used in advertisements as an ideal
pastoral picture: flowering meadows, plump with health
cows with traditional bells. The cow is one of
well-known symbols of Switzerland. Meanwhile, in the 1990s this
the country was among those European states where the
a real agricultural and human tragedy. Although
She then bypassed Russia, we all remember her under the name
epidemic of mad cow disease, it is also transmissible
bovine spongiform encephalopathy.
It all started with the fact that in 1986 in the UK there were
the first cases of a strange illness are registered. Animals
problems with coordination were observed, they became shy and
aggressive, losing weight, finally, their legs gave out and they
died. At autopsy, it turned out that there were no
signs of infectious inflammation, but sections of brain tissue under
look like lace under a microscope, but it looks like a sponge,
hence the name. At that time, similar signs in veterinary medicine
were not unique: scientists have described similar fatal and
infectious diseases in sheep, goats, wild and domestic deer,
minks, horses.
In subsequent years, the epidemic (or rather epizootic) rapidly
spread throughout the counties of England. It peaked at
1992, spread to the European continent, faded for a long time
years, affected a total of 40 countries and cost lives
millions of animals. Even wild ungulates in
zoos. In Great Britain itself had to be preventively destroyed
all cattle, the country has turned from an exporter into
importer of meat, and in European countries to eliminate the consequences of
in total, hundreds of billions of euros were spent. But it wasn’t the most
terrible. People did not immediately discover what the epidemic represents
mortal danger to themselves.
On the infectious character of some similar diseases with spongy
damage to various parts of the brain has been known for a long time: for
Sheep infectiousness was confirmed in the laboratory at the end of the 19th century.
Human fatal ailments with progressive destruction
brain cells and speckling of the contents of the head like a sponge on
That moment was recorded already four. “These are terrible
diseases, but, fortunately, they are not so common,
reassured us Adriano Aguzzi. Known since 1920 disease
Creutzfeldt-Jakob, spastic pseudosclerosis, first
considered a spontaneously occurring disease in the elderly
(one or two cases per 1 million population), but by the end of the 1960s.
managed to prove that it can be infectious. With time
confirmed that, spontaneously occurring in one individual, the disease
can be passed on to others through medications and
food manipulation. For one more – kuru, Guinean diseases
aborigines, – a quarter of a century before that, it was firmly established
alimentary mode of transmission through ritual cannibalism
(eating the dead). American scientist Daniel Carlton Gajdushek,
who studied the life of tribes, managed in the laboratory
transfer the chicken to the chimpanzee and proved its infectious nature,
received for this the Nobel Prize in Physiology or Medicine at 1976
d. When the natives were forbidden to eat their ancestors, this disease went
on the wane.
The causative agent, however, was not established, and the medical world for a long time
time believed that the culprits of such partially similar
symptoms of human and animal diseases are some
viruses. Spongiform encephalopathies are characterized by extremely
long incubation period (up to 10-30 years or more), therefore, in
scientific circles have been labeling putative pathogens for decades
“slow viruses”. However, at 1970s showed up
phenomenal vitality of these mysterious infectious
agents: neither ultraviolet nor
ionization, no microwave radiation, no sterilization in
autoclave. “Unlike all known viruses, they do not
collapsed under the influence of 120 and even 400 degrees of dry
heat. It was very strange. Scientists have experimented
trying to identify nucleic acids, but this did not give
result, which was a big surprise, since all life is
The earth is encoded in nucleic acids – DNA and RNA. In that
moment it seemed inconceivable that an infectious agent could
reproduce itself without any genetic information!”
– tries to convey the surprise of his predecessors professor
Aguzzi.
What is this invisibility? Mysterious killer turned out to be… a protein
those. a protein with a normal composition, however, with an abnormal
spatial structure of the molecule.
Killer Steak
Last spring, when “Ideas that Change the World” with Adriano
The aguzzi had already been edited and were being prepared for airing,
professor came to Moscow. He read on biological
Faculty of Moscow State University an open lecture on prion diseases
mammals. On the faculty website
Facebook there is a photo report about this event. For
interested in the topic of prions, this was a unique opportunity: the presenter
a world expert in molecular biology was available for
any specific questions.
However, for a wide audience of non-specialists, the professor outlined
the essence of modern prion knowledge in much more accessible language
in our TV program. Prion is a combination of the words “protein” and
“infection” ( PRION – PRotein Infectivity ONly) . First
this hitherto elusive culprit of degenerative processes
identified at 1982 San Francisco neurologist Stanley
Prusiner. His hypothesis of an infectious killer protein threatened
overturn many dogmas in the field of physiology and medicine, and
therefore, many at first took his idea with hostility (including
kuru researcher, virologist Gaidushek). Your Nobel Prize
in medicine, Prusiner received only 15 years after the landmark
discoveries.
“How can a protein reproduce itself without genetic information?
It has now been well studied. It turns out that in our body
there is another protein, and this is a normal intracellular
physiological protein ( PrPC ). A pathological prion
protein ( PrPSc ) attacks this normal prion protein and
turns it into a copy of itself. So no
need for additional genes,” explains Prof. Aguzzi
Russian TV viewers. Thus, these proteins have absolutely
the same amino acid composition, only differently folded
chain. The “bad” form of the protein accumulates in the cells of neurons,
forming clots and causing their death. “He reproduces himself in
huge amounts, especially in the brain – usually in the brain
animals such as cows and sheep. Then you can take this brain and
to infect other animals with it.”
This is exactly what happened in the case of bovine spongiform encephalitis.
An epidemic disease of English cows, as it turned out, too
provoked cannibalism. In those years, livestock breeders everywhere
used as top dressing for ruminants industrially
recycled remains of their kind. No problems with veterinarians
it was not associated. However, according to the special
literature, on the eve of the mad cow disease epidemic in pursuit
for greater nutritional value, manufacturers have changed something in
technologies for the production of meat and bone meal. And tenacious prions from
disposed of infected carcasses were fed to healthy
cows. It is possible that the brains of rams suffering from
scrapie disease (in Russian – pruritus), prion disease
sheep and goats. Scientists have found that sheep serve as a natural
natural reservoirs of an infectious agent: in their body
The prion protein is generated spontaneously and passed on. IN
Great Britain through eating contaminated meat were infected
street cats, cougars and antelopes in the zoo.
Along the food chain, prion protein got from cows and into the body to
to a person. At that moment, when the mass loss of livestock had already begun to go
on the wane, physicians have recorded that human disease
Creutzfeldt – Jacob suddenly “looked younger” If in her
In the classical form, it affected people over 50 years old, then since 1995.
20-year-old patients began to appear. progressive
dementia in the prime of life! However, the most tragic
fatal deterioration occurred against the background of awareness
a person of the misfortune happening to him: depression, insomnia,
impaired coordination of movements, loss of ability to serve
yourself and yourself have, finally, memory loss, clouding
consciousness and inevitable death.
Reports of this so-called new variant of the disease
Creutzfeldt – Jacob began to arrive from different countries. TO
mid-2005, contaminated beef caused more than
one and a half hundred citizens in Great Britain alone. Taking into account
duration of the incubation period (from five months to 15
years) the final number of infected in that period can be understood
only years later. Food industry specialists
argue that meat with prions during the years of the epizootic could
used by several million people worldwide.
At the same time, in the 1980s Dozens of deaths have been recorded
CJD, when patients had the misfortune to become infected through non-sterile
surgical instruments, grafts (e.g. cornea
eyes) and hormonal injections. Today already
It is known that short-term contact with
pathological prion protein in a certain concentration per
surgeon’s scalpel to the body’s normal prion protein
a chain reaction started. “The minimum dose of prions that
infects 50% of animals in the experiment, is about 100
thousand molecules,” says Professor Aguzzi. – This is very
a small amount, but, as you understand, if the dose
increase, the probability will increase.
Old age is joy
And what did Mr. Aguzzi himself and
institution headed by him? “For the past 15 years, I have struggled with
How does a prion that enters the stomach with food get into
brain. This is a non-trivial question. The prion must get through
stomach walls, bypass the immune system, overcome
blood-brain barrier and end up in the brain. And I can
to say that in my laboratory they understood which molecules, which
cells play a role in this process and how can we
hinder. In the next “chapter” of research, I will
understand why these clots are so toxic that they kill
nerve cells”.
In his interviews, Aguzzi spoke in the spirit that Europe would
face the echoes of the mad cow disease epidemic for at least
half a century. Prions can be spread through donated materials
and animal-based medicines (like the usual
Russians actovegin and solcoseryl from the blood of calves, which during
many countries have long been banned), as well as through non-disposable
tools for operations, especially on the brain.
“In addition, we found in the laboratory that prions can
transmitted by aerosols. Of course, if someone is near
sneezes at you, this does not mean that it comes out of it at that moment
brain. Do not worry: in a normal everyday situation, you are unlikely to
Do you get infected through aerosols? But in a science lab it can
happen. If a laboratory assistant homogenizes the brain, and around
homogenizer will turn out to be an aerosol, it can be very dangerous,
so we always use biological protection.”
But what does Alzheimer’s, Parkinson’s, senile
dementia, age-related dementia and other possible risks
longevity? After all, these neurodegenerative diseases are not
to prion diseases, spongiform encephalopathies. Adriano Aguzzi
explained to us the connection: “Alzheimer’s disease is extremely
common. One in three people over 85 have it
disease. Curiously, in Alzheimer’s disease, there are
deposits of abnormal proteins that are very similar to
prion. Of course, the molecular structure is a different protein
– in the case of Alzheimer’s disease, it is called beta-amyloid, but
deposits are similar, they have the same biophysics. When
parkinsonism, we are dealing with a third type of protein – synuclein.
This protein is also aggregated and deposited in neurons,
destroys them. Naturally, the question arises: what if diseases
Alzheimer’s and Parkinson’s – infectious?
Of course, it is an intrigue and a terrific challenge for a scientist to find the key
to those riddles of fading that most people now
are considered simply the natural course of things, signs of old age.
After all, why then all the fuss around rejuvenation and maintenance
health of the body, if the intellect dies much earlier? Colleagues
Adriano Aguzzi in the USA has already created a synthetic drug from
purified recombinant synuclein and, by introducing it into a laboratory
mice caused Parkinson’s disease in them. And once you can
to infect, someday an antidote may be found.
Of course, such discoveries can give rise to the public and
paranoid questions: what if such diseases can be
infect artificially? It’s a social problem: millions
dependents, a huge burden on the economy. Maybe this
an instrument of evolution and we ourselves do not know what we are interfering with?
Evelina Zakamskaya, host of Ideas that Change the World, discussed with
Professor Aguzzi many similar questions with ethical and even
philosophical overtones. But the scientist is optimistic and
hopes that he will have time to understand the mechanism of transformation and discover
decision during his own scientific career: “I do not believe that
such a fate awaits us all. It’s the same disease as everyone else
the rest, you just need to find the right medicine.
In any case, Adriano Aguzzi is still quite a young man, and
this outstanding scientist has not yet received his Nobel Prize.
And this means that we all really have a chance.
Biologists have revealed the secret of the contagiousness of mad cow disease 09/09/2016
Biologists have discovered the secret of contagiousness of mad cow disease
For the first time, scientists have unraveled the molecular structure of prions, the proteins that cause mad cow disease, and unlocked the secrets of how these molecules grow when ingested and how they self-replicate in a healthy brain.
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discoveries – RIA Science, Canada, Alzheimer’s disease, neurophysiology
Discoveries – RIA Science, Science, Canada, Alzheimer’s disease, neurophysiology
MOSCOW, September 9 – RIA Novosti . For the first time, scientists have unraveled the structure of the molecules of prions, the proteins that cause mad cow disease, and revealed the secrets of how these molecules grow when they enter the body and how they self-replicate in a healthy brain, according to an article published in the journal PLOS Pathogens.
“Until now, we knew what “healthy” prion proteins look like, but we did not understand how the infectious versions of these proteins are arranged and how they spread throughout the body. The latest technologies in cryomicroscopy have allowed us to get closer to answering this question,” – said Holger Wille from the University of Alberta (Canada).
Spongiform encephalopathy, Creutzfeldt-Jakob disease, is usually called “mad cow disease” in the press and among the townsfolk. It is not caused by bacteria or viruses, but by so-called prions – tangled and damaged proteins. When prions enter the body, they trigger the conversion of proteins similar to them into prion molecules. The accumulation of prions in neurons leads to their destruction, the development of severe disorders in the brain and then to death.
A person or any animal can become a victim of “mad cow disease” by eating the nervous tissue of an already sick animal. So far, scientists do not know how the damaged proteins contained in them penetrate the body and why the disease does not develop immediately, but after 7-10 years of the “incubation period”, including because the study of the three-dimensional structure of prions is almost impossible due to their supercomplex form.
Alzheimer’s disease can be contagious, neurophysiologists have found out
September 9, 2015, 20:08
Wille and his colleagues took the first step towards uncovering the causes of the development of “mad cow disease”, spending the last three years deciphering the structure of one of the prion variants, with which they caused spongiform encephalopathy in rodents.
Using thousands of snapshots of molecules extracted from the brains of mice and frozen to near absolute zero, biologists have compiled a three-dimensional ‘identikit’ of the prion, allowing them to get their first look at how this molecule is arranged and what parts it consists of. This is a very schematic portrait of prions – you cannot see individual atoms on it, but the clarity of the image is enough to understand how its parts are connected to each other and how these connections appeared.
Scientists have figured out how “mad cow disease” enters the brain of animals
September 22, 2015, 16:45
volumes.