Mad Cow Disease

06/10/2022

Public health control measures, such as surveillance, culling sick animals, or banning specified risk materials, have been instituted in many countries, particularly in those with indigenous cases of confirmed BSE, in order to prevent potentially BSE-infected tissues from entering the human food supply.

06/10/2022

What is the FDA Doing to Keep Your Food Safe?
The U.S. Food and Drug Administration (FDA) is doing many things to keep the food in the U.S. safe for both people and cows. Since August 1997, the FDA has not allowed most parts from cows and certain other animals to be used to make food that is fed to cows. This protects healthy cows from getting BSE by making sure that the food they eat is not contaminated with the abnormal prion.
cows at feed trough
boxer eating from a pet dish
In April 2009, the FDA took additional steps to make sure the food in the U.S. stays safe. Certain high-risk cow parts are not allowed to be used to make any animal feed, including pet food. This prevents all animal feed from being accidentally contaminated with the abnormal prion. High-risk cow parts are those parts of the cow that have the highest chance of being infected with the abnormal prion, such as the brains and spinal cords from cows that are 30 months of age or older.
By keeping the food that is fed to cows safe, the FDA is protecting people by making sure that the food they eat comes from healthy cows.
meat
The FDA also works with the U.S. Department of Agriculture (USDA) to keep cows in the U.S. healthy and free of BSE. The USDA prevents high-risk cows and cow products from entering the U.S. from other countries. The USDA also makes sure that high-risk cow parts, such as the brains and spinal cords, and cows that are unable to walk or that show other signs of disease are not used to make food for people.
The steps the FDA and USDA have taken to prevent cows in the U.S. from getting BSE are working very well. Only six cows with BSE have been found in the U.S. The first case was reported in 2003 and the most recent case was found in August 2018.
It is worth noting that there are two types of BSE, classical and atypical. Classical is caused by contaminated feed fed to cows. Atypical is rarer and happens spontaneously, usually in cows 8-years-old or older. Of the six U.S. cows found with BSE, five were atypical. The only case of classical BSE in the U.S. was the first one, in 2003, in a cow imported from Canada.

06/10/2022

Can People Get BSE?
People can get a version of BSE called variant Creutzfeldt-Jakob disease (vCJD). As of 2019, 232 people worldwide are known to have become sick with vCJD, and unfortunately, they all have died. It is thought that they got the disease from eating food made from cows sick with BSE. Most of the people who have become sick with vCJD lived in the United Kingdom at some point in their lives. Only four lived in the U.S., and most likely, these four people became infected when they were living or traveling overseas.

Neither vCJD nor BSE is contagious. This means that it is not like catching a cold. A person (or a cow) cannot catch it from being near a sick person or cow. Also, research studies have shown that people cannot get BSE from drinking milk or eating dairy products, even if the milk came from a sick cow.

06/10/2022

What are the Signs of BSE in Cows?
A common sign of BSE in cows is incoordination. A sick cow has trouble walking and getting up. A sick cow may also act very nervous or violent, which is why BSE is often called “mad cow disease.”
It usually takes four to six years from the time a cow is infected with the abnormal prion to when it first shows symptoms of BSE. This is called the incubation period. During the incubation period, there is no way to tell that a cow has BSE by looking at it. Once a cow starts to show symptoms, it gets sicker and sicker until it dies, usually within two weeks to six months. There is no treatment for BSE and no vaccine to prevent it.

Currently, there is no reliable way to test for BSE in a live cow. After a cow dies, scientists can tell if it had BSE by looking at its brain tissue under a microscope and seeing the spongy appearance. Scientists can also tell if a cow had BSE by using test kits that can detect the abnormal prion in the brain.

06/10/2022

What Causes BSE?
Most scientists think that BSE is caused by a protein called a prion. For reasons that are not completely understood, the normal prion protein changes into an abnormal prion protein that is harmful. The body of a sick cow does not even know the abnormal prion is there. Without knowing it is there, the cow’s body cannot fight off the disease.

06/10/2022

How Does a Cow Get BSE?
baby calf lying down
The parts of a cow that are not eaten by people are cooked, dried, and ground into a powder. The powder is then used for a variety of purposes, including as an ingredient in animal feed. A cow gets BSE by eating feed contaminated with parts that came from another cow that was sick with BSE. The contaminated feed contains the abnormal prion, and a cow becomes infected with the abnormal prion when it eats the feed. If a cow gets BSE, it most likely ate the contaminated feed during its first year of life. Remember, if a cow becomes infected with the abnormal prion when it is one-year-old, it usually will not show signs of BSE until it is five-years-old or older.

20/08/2022

Mad Cow Disease (Spongiform Encephalopathy or BSE)
Mad cow disease, or bovine spongiform encephalopathy (BSE), is a disease that was first found in cattle. It's related to a disease in humans called variant Creutzfeldt-Jakob disease (vCJD). Both disorders are universally fatal brain diseases caused by a prion. A prion is a protein particle that lacks DNA (nucleic acid). It's believed to be the cause of various infectious diseases of the nervous system. Eating infected cattle products, including beef, can cause a human to develop mad cow disease.
What is mad cow disease?
Mad cow disease is a progressive, fatal neurological disorder of cattle resulting from infection by a prion. It appears to be caused by contaminated cattle feed that contains the prion agent. Most mad cow disease has happened in cattle in the United Kingdom (U.K.), a few cases were found in cattle in the U.S. between 2003 and 2006. Feed regulations were then tightened.
In addition to the cases of mad cow reported in the U.K. (78% of all cases were reported there) and the U.S., cases have also been reported in other countries, including France, Spain, Netherlands, Portugal, Ireland, Italy, Japan, Saudi Arabia, and Canada. Public health control measures have been implemented in many of the countries to prevent potentially infected tissues from entering the human food chain. These preventative measures appear to have been effective.

13/10/2021

Mad cow disease, also called Creutzfeldt-Jakob Disease (CJD), is a fatal disease that slowly destroys the brain and spinal cord in cattle. People cannot get mad cow disease. However, in rare cases they can get a human form of mad cow disease called variant Creutzfeldt-Jakob disease (vCJD), which is also fatal.

04/07/2021

03/07/2021

03/07/2021

How is CJD diagnosed?
Several tests can help diagnose CJD.

Electroencephalography (EEG), which records the brain’s electrical pattern, can be particularly valuable because it shows a specific type of abnormality in major but not all types of CJD.
Cerebrospinal fluid-based tests. In April 2015, the National Prion Disease Pathology Surveillance Center began reporting a new diagnostic test for human prion diseases, called second generation Real Time-Quaking-Induced Conversion (RT-QuIC). RT-QuIC is based on an ultrasensitive detection of the pathogenic prion protein in the cerebrospinal fluid of individuals affected by CJD and other forms of human prion diseases. This new advanced test demonstrates a very high sensitivity and specificity of the disease. RT-QuIC differs from traditional surrogate markers of prion disease –14-3-3 and tau proteins—in that it detects directly a disease-defining pathogenic prion protein as opposed to a surrogate marker of rapid neurodegeneration. Detection of these traditional surrogate marker proteins is accurate in approximately three-fourths of cases.
Magnetic resonance imaging (MRI) has recently been found to be accurate in about 90 percent of cases.
The only way to confirm a diagnosis of CJD is by brain biopsy or autopsy. In a brain biopsy, a neurosurgeon removes a small piece of tissue from the person’s brain so that it can be examined by a neuropathologist. This procedure may be dangerous for the individual, and the operation does not always obtain tissue from the affected part of the brain. Because a correct diagnosis of CJD does not help the individual, a brain biopsy is discouraged unless it is needed to rule out a treatable disorder. In an autopsy, the whole brain is examined after death.

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How is the disease treated?
Currently, there is no treatment that can cure or control CJD, although studies of a variety of drugs are now in progress. Current treatment for CJD is aimed at easing symptoms and making the person as comfortable as possible. Op**te drugs can help relieve pain if it occurs, and the drugs clonazepam and sodium valproate may help relieve myoclonus. During later stages of the disease, intravenous fluids and artificial feeding also may be used.

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How can people avoid spreading the disease?
To reduce the already very low risk of CJD transmission from one person to another, people should never donate blood, tissues, or organs if they have suspected or confirmed CJD, or if they are at increased risk because of a family history of the disease, a dura mater graft, or other factor.

Normal sterilization procedures such as cooking, washing, and boiling do not destroy prions. Although there is no evidence that caregivers, healthcare workers, and those who prepare bodies for funerals and cremation have increased risk of prion diseases when compared to general population, they should take the following precautions when they are working with a person with CJD:

Cover cuts and abrasions with waterproof dressings.
Wear surgical gloves when handling the person’s tissues and fluids or dressing any wounds.
Avoid cutting or sticking themselves with instruments contaminated by the person’s blood or other tissues.
Use disposable bedclothes and other cloth for contact with the person.If disposable materials are not available, regular cloth should be soaked in undiluted chlorine bleach for an hour or more, and then washed in a normal fashion after each use.
Use face protection if there is a risk of splashing contaminated material such as blood or cerebrospinal fluid.
Soak instruments that have come in contact with the person in undiluted chlorine bleach for an hour or more, then use an autoclave (pressure cooker) to sterilize them in distilled water for at least one hour at 132 - 134 degrees Celsius.
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What research is taking place?
The mission of the National Institute of Neurological Disorders and Stroke (NINDS) is to seek fundamental knowledge of the brain and nervous system and to use that knowledge to reduce the burden of neurological disease. The NINDS is a component of the National Institutes of Health (NIH), the leading supporter of biomedical research in the world.

Other NIH Institutes, including the National Institute of Allergy and Infectious Diseases and the National Institute on Aging, also conduct research on CJD.

Researchers are examining and characterizing the prions associated with CJD and other human and animal prion diseases and trying to discover factors that influence prion infectivity and transmission, and how the disorder damages the brain. For example, researchers are investigating the cellular mechanisms involved in abnormal prion formation and accumulation, as well as their replication by select cellular subsets in the brain. Other projects are examining how abnormal prions cross the protective blood-brain barrier and spread throughout the central nervous system, and tests that measure the biological activity of prions. Findings may identify new therapeutic targets to treat prion diseases.

More information about CJD research supported by NINDS and other NIH Institutes and Centers can be found using NIH RePORTER, a searchable database of current and past research projects supported by NIH and other federal agencies. RePORTER also includes links to publications and resources from these projects.

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How can I help research?
Scientists are conducting biochemical analyses of brain tissue, blood, spinal fluid, urine, and serum in the hope of determining the nature of the transmissible agent or agents causing CJD. To help with this research, they are seeking biopsy and autopsy tissue, blood, and cerebrospinal fluid from individuals with CJD and related diseases. The following investigators have expressed an interest in receiving such material:

03/07/2021

How is CJD transmitted?
CJD cannot be transmitted through the air or through touching or most other forms of casual contact. Spouses and other household members of people with sporadic CJD have no higher risk of contracting the disease than the general population. However, exposure to brain tissue and spinal cord fluid from infected persons should be avoided to prevent transmission of the disease through these materials.

In some cases, CJD has spread to other people from grafts of dura mater (a tissue that covers the brain), transplanted corneas, implantation of inadequately sterilized electrodes in the brain, and injections of contaminated pituitary growth hormone derived from human pituitary glands taken from cadavers. Doctors call these cases that are linked to medical procedures iatrogenic cases. Since 1985, all human growth hormone used in the United States has been synthesized by recombinant DNA procedures, which eliminates the risk of transmitting CJD by this route.

Many people are concerned that it may be possible to transmit CJD through blood and related blood products such as plasma. Some animal studies suggest that contaminated blood and related products may transmit the disease, although this has never been shown in humans. Recent studies suggest that while there may be prions in the blood of individuals with vCJD, this is not the case in individuals with sporadic CJD. Scientists do not know how many abnormal prions a person must receive before he or she develops CJD, so they do not know whether these fluids are potentially infectious or not. They do know that, even though millions of people receive blood transfusions each year, there are no reported cases of someone contracting sporadic CJD from a transfusion. Even among people with hemophilia (a rare bleeding disorder in which the blood does not clot normally), who sometimes receive blood plasma concentrated from thousands of donors, there are no reported cases of CJD.

While there is no evidence that blood from people with sporadic CJD is infectious, studies have found that infectious prions from BSE and vCJD accumulate in the lymph nodes (which produce white blood cells), the spleen, and the tonsils. At present, four cases of vCJD infection have been identified following transfusion of red blood cells from asymptomatic donors who subsequently died from vCJD. Recently, one case of likely transmission of vCJD infection by concentrates of blood-clotting protein has been reported in an elderly individual with hemophilia in the United Kingdom. The possibility that blood from people with vCJD may be infectious has led to a policy preventing individuals in the United States from donating blood if they have resided for more than three months in a country or countries where BSE is common.

Both brain biopsy and autopsy pose a small, but definite, risk that the surgeon or others who handle the brain tissue may become accidentally infected by self-inoculation.

Special surgical and disinfection procedures can markedly reduce this risk. A fact sheet with guidance on these procedures is available from the National Institute of Neurological Disorders and Stroke (NINDS) and the World Health Organization.

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03/07/2021

What causes CJD?
Current scientific consensus maintains that abnormal forms of normal cellular proteins called prions cause CJD in people and TSE in animals. The normal, harmless prion is usually designated PrPC (C stands for cellular) and the abnormal, infectious form (which causes the disease) is PrPSc (Sc stands for prototypical prion disease–scrapie).

Proteins are long chains of amino acids that have to fold together into a unique shape or conformation to gain function in the cells. Research findings indicate that the infectious prion originates from a normal protein whose conformation has changed to one that causes the disease. The normal prion protein is found throughout the body but is most abundant in the nervous system. Its overall role is not fully understood. It is believed that the harmless to infectious protein conformational change is common to the all major forms of human prion disease, including CJD. In the acquired form of the disease, the PrPSc comes from the outside the body, for example, through contaminated meat as is seen in vCJD. It then clings to and changes the conformation of the normal prion protein of the host and progressively spreads in domino-like fashion toward the brain where it causes lesions.

In the hereditary form, infectious prions can arise when a mutation occurs in the gene for the body’s normal prion protein. As the mutated PrPC replicates itself, it spontaneously changes shape into the infectious form. (Prions themselves do not contain genetic information and do not require genes to reproduce themselves.) If the prion protein gene is altered in a person’s s***m or egg cells, the mutation can be transmitted to the person’s offspring. Several different mutations in the prion gene have been identified. The particular mutation found in each family affects how frequently the disease appears and what symptoms are most noticeable. However, not all people with mutations in the prion protein gene develop CJD.

In the sporadic form, the infectious prions are believed to be made by an error of the cell machinery that makes proteins and controls their quality. These errors are more likely to occur with aging, which explains the general advanced age at onset of CJD and other prion diseases. Once they are formed, abnormal prion proteins aggregate, or clump together. Investigators think these protein aggregates lead to the nerve cell loss and other brain damage seen in CJD. However, they do not know exactly how this damage occurs.

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03/07/2021

What are the symptoms of the disease?
Although sporadic TSE includes five distinct subtypes of sporadic CJD and sporadic fatal insomnia (sFI), overall they are characterized by rapidly progressive dementia. Initially, individuals experience problems with muscle coordination, personality changes (including impaired memory, judgment, and thinking), and impaired vision. People with the disease, especially with FFI, also may experience insomnia, depression, or unusual sensations. As the illness progresses, peoples’ mental impairment becomes severe. They often develop involuntary muscle jerks called myoclonus, and they may go blind. They eventually lose the ability to move and speak, and enter a coma. Pneumonia and other infections often occur in these individuals and can lead to death.

Variant CJD begins primarily with psychiatric symptoms, affects younger individuals than other types of CJD, and has a longer than usual duration from onset of symptoms to death.

Some symptoms of CJD can be similar to symptoms of other progressive neurological disorders, such as Alzheimer’s and Huntington’s disease. However, CJD causes unique changes in brain tissue which can be seen at autopsy. It also tends to cause more rapid deterioration of a person’s abilities than Alzheimer’s disease or most other types of dementia.

03/07/2021

What is Creutzfeldt-Jakob disease?
Creutzfeldt-Jakob disease (CJD) is a rare, degenerative, fatal brain disorder. It affects about one person in every one million per year worldwide; in the United States there are about 350 cases per year. CJD usually appears in later life and runs a rapid course. Typical onset of symptoms occurs at about age 60, and about 70 percent of individuals die within one year. In the early stages of the disease, people may have failing memory, behavioral changes, lack of coordination, and visual disturbances. As the illness progresses, mental deterioration becomes pronounced and involuntary movements, blindness, weakness of extremities, and coma may occur.

There are three major categories of CJD.

In sporadic CJD, the disease appears even though the person has no known risk factors for the disease. This is by far the most common type of CJD and accounts for at least 85 percent of cases.
In hereditary CJD, the person may have a family history of the disease and test positive for a genetic mutation associated with CJD. About 10 to 15 percent of cases of CJD in the United States are hereditary.
In acquired CJD, the disease is transmitted by exposure to brain or nervous system tissue, usually through certain medical procedures. There is no evidence that CJD is contagious through casual contact with someone who has CJD. Since CJD was first described in 1920, fewer than one percent of cases have been acquired CJD. A type of CJD called variant CJD (or vCJD) can be acquired by eating meat from cattle affected by a disease similar to CJD called bovine spongiform encephalopathy (BSE) or, commonly, “mad cow” disease.
CJD belongs to a family of human and animal diseases known as the transmissible spongiform encephalopathies (TSEs) or prion diseases. A prion—derived from “protein” and “infectious”—causes CJD in people and TSEs in animals. Spongiform refers to the characteristic appearance of infected brains, which become filled with holes until they resemble sponges when examined under a microscope. CJD is the most common of the known human TSEs. Other human TSEs include kuru, fatal familial insomnia (FFI), and Gerstmann-Straussler-Scheinker disease (GSS). Kuru was identified in people of an isolated tribe who practiced ritual cannibalisms in Papua, New Guinea and has now almost disappeared. Kuru is considered an acquired prion disease. FFI and GSS are extremely rare hereditary diseases, found in just a few families around the world. To date, about 260 cases of vCJD, mostly in the United Kingdom, have been reported related to consuming beef but none in which the disease was acquired in the U.S. Other TSEs are found in specific kinds of animals. These include BSE, mink encephalopathy, feline encephalopathy, and scrapie, which affects sheep and goats. Chronic wasting disease (CWD) affects elk and deer and is increasingly prevalent in certain areas in the United States. To date no transmission of CWD to humans has been reported.

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03/07/2021

What Other Countries Have Reported Cases of Mad Cow Disease?
The disease also has been confirmed in cattle born in Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Italy, Ireland, Israel, Japan, Liechtenstein, Luxembourg, the Netherlands, Poland, Portugal, Slovakia, Slovenia, Spain, Switzerland, and the U.K.

Canada has also been added to the list of countries from which imports are restricted, although that ban has been lifted recently. Importation of minimal-risk meat products is now allowed from Canada.

03/07/2021

How Long Have Health Officials Been Concerned About Mad Cow Disease?
Mad cow disease has been of great concern since 1986, when it was first reported among cattle in the U.K. At its peak in January 1993, almost 1,000 new cases per week were identified. Concern about this disease grew significantly in 1996 when an association between mad cow disease and vCJD in humans was discovered.

03/07/2021

What Is the Current Risk of vCJD to Americans Traveling Abroad?
According to the CDC, the current risk of acquiring vCJD from any specific country appears to be extremely small. But that cannot be precisely determined because cattle products from one country might be distributed and consumed in others.

03/07/2021

What About Other Products Made From Cow By-Products?
The FDA stops the importation of cosmetic and dietary supplement ingredients containing bovine materials from animals originating in the 33 countries where mad cow disease has been found or from animals at risk of being infected.

03/07/2021

Can You Get vCJD From Drinking Milk From an Infected Cow?
Milk and milk products are not believed to pose any risk for transmitting mad cow disease to humans. Experiments have shown that milk from mad cow-infected cows has not caused infections.

03/07/2021

Is it Possible to Get vCJD From Eating Food Purchased in the U.S.?
It is extremely unlikely that this would happen. To prevent mad cow disease from entering the country, since 1989 the federal government has prohibited the importation of certain types of live animals from countries where mad cow disease is known to exist. This ban includes meat products used in human, animal, and pet foods. In addition, prohibiting high-risk animals from entering the food supply and the removal of central nervous system tissue from the food supply helps assures that BSE is not a risk to consumers.

03/07/2021

What Are the Symptoms of vCJD?
The disease can affect all age groups and is very hard to diagnose until it has nearly run its course. In the early stages of vCJD, people have symptoms related to the nervous system, like depression and loss of coordination. Later in the illness, dementia develops. But only in advanced stages of the disease can brain abnormalities be detected by MRI (magnetic resonance imaging). vCJD is fatal, usually within 13 months of the onset of symptoms.

03/07/2021

It is important to clarify the differences between variant CJD and another form of the disease, referred to as classic or sporadic CJD. Classic CJD has no known cause and occurs each year at a rate of one to two cases per 1 million people throughout the world, including in the U.S. and countries where mad cow disease has never occurred. It is not linked to eating nerve tissue from mad cow disease-affected cattle -- both vegetarians and meat eaters have died from classic CJD. CJD most commonly affects people over 65 and is usually fatal within six months from onset of symptoms.

03/07/2021

What Is Mad Cow Disease?
Mad cow disease, or bovine spongiform encephalopathy (BSE), is a transmissible, slowly progressive, degenerative, and fatal disease affecting the central nervous system of adult cattle. The U.S. Department of Agriculture (USDA) has tested hundreds of thousands of cattle for BSE.

Researchers believe that the infectious agent that causes mad cow disease is an abnormal version of a protein normally found on cell surfaces, called a prion. For reasons still unknown, this protein becomes altered and destroys nervous system tissue -- the brain and spinal cord.

Does Cooking Food Kill the Prion That Causes Mad Cow Disease?
Common methods to eliminate disease-causing organisms in food, like heat, do not affect prions. Also, prions only seem to live in nervous system tissue.

Does Mad Cow Disease Affect Humans?
A human version of mad cow disease called variant Creutzfeldt-Jakob disease (vCJD) is believed to be caused by eating beef products contaminated with central nervous system tissue, such as brain and spinal cord, from cattle infected with mad cow disease. For this reason, the USDA requires that all brain and spinal cord materials be removed from high-risk cattle -- older cattle, animals that are unable to walk, and any animal that shows any signs of a neurological problem. These cow products do not enter the U.S. food supply. The USDA believes this practice effectively safeguards U.S. public health from vCJD.

According to the CDC, four deaths from vCJD have been identified in the U.S. However, it's believed those cases were caused by consumption of meat outside the U.S.