Symptoms, Causes and Treatments for vCJD

Written by Michael W. Smith, MD

• Mad cow disease has hit the U.S. and questions about this mysterious disease abound. Here’s what you need to know about mad cow disease.
• What Is Mad Cow Disease?
• Does Cooking Food Kill the Prion That Causes Mad Cow Disease?
• Does Mad Cow Disease Affect Humans?
• What Are the Symptoms of vCJD?
• Is it Possible to Get vCJD From Eating Food Purchased in the U.S.?
• Can You Get vCJD From Drinking Milk From an Infected Cow?
• What About Other Products Made From Cow By-Products?
• What Is the Current Risk of vCJD to Americans Traveling Abroad?
• How Long Have Health Officials Been Concerned About Mad Cow Disease?
• What Other Countries Have Reported Cases of Mad Cow Disease?
• More

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.

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.

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.

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.

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.

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 help ensure that BSE is not a risk to consumers.

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.

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.

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.

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.

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.

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Symptoms, Causes and Treatments for vCJD

Written by Michael W. Smith, MD

• Mad cow disease has hit the U.S. and questions about this mysterious disease abound. Here’s what you need to know about mad cow disease.
• What Is Mad Cow Disease?
• Does Cooking Food Kill the Prion That Causes Mad Cow Disease?
• Does Mad Cow Disease Affect Humans?
• What Are the Symptoms of vCJD?
• Is it Possible to Get vCJD From Eating Food Purchased in the U. S.?
• Can You Get vCJD From Drinking Milk From an Infected Cow?
• What About Other Products Made From Cow By-Products?
• What Is the Current Risk of vCJD to Americans Traveling Abroad?
• How Long Have Health Officials Been Concerned About Mad Cow Disease?
• What Other Countries Have Reported Cases of Mad Cow Disease?
• More

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.

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.

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.

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.

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.

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 help ensure that BSE is not a risk to consumers.

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.

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.

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.

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.

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.

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what you need to know about mad cow disease

The Department of Veterinary Medicine of the Sverdlovsk Region warns owners of cattle about the danger of importing into the country from disadvantaged zones or countries of breeding stock, meat, canned food, offal and semi-finished products, meat and bone meal, sperm, embryos, technical fat, intestinal raw materials and other products and feeds of animal origin from ruminants. In order to prevent mad cow disease infection, it is necessary to inform veterinary clinics in a timely manner.

What is mad cow disease?

Bovine spongiform encephalopathy (BSE), or mad cow disease, is a slowly developing infectious prion transmissible disease of adult cattle, characterized by a long, up to 2.5-8 years, incubation period and manifested by damage to the central nervous system with 100% mortality.

Historical reference.

Spongiform encephalopathy was first reported in 1985-1986 in the UK under the name “mad cow disease”. In the next 10 years, BSE spread to other countries: France, Portugal, Switzerland, Germany, the Netherlands, Italy, Denmark, Slovakia, Finland, etc.

scrapie cattle (scrapie) – a similar agent (causative agent of sheep scrapie), found in meat and bone meal, which was included in the diet of cattle. In Russia, the disease has not been registered.

Economic damage.

BSE caused enormous economic damage to European countries, due to the fact that about 4 million heads of cattle were destroyed. The UK alone suffered an economic loss of £7 billion.

Epizootological data.

Under natural conditions, cattle are susceptible to BSE, especially at 4 years of age. The source of the causative agent of infection are sick and animals in the incubation period. The factors of transmission of the infectious agent are the products of slaughter of sheep with scrapie, and cattle with EH.

Course and symptoms of the disease.

The incubation period is from 2.5 to 8 years, in some cases it can be extended up to 25-30 years. The course of the disease is progressive, without remissions. The disease proceeds without an increase in body temperature of the animal, with continued appetite. Despite a normal appetite, cows have reduced milk production.

The clinical manifestation of the disease is characterized by signs of damage to the central nervous system.

Three types of nervous phenomena are detected during GE.

• The first type of nervous phenomena is accompanied by the development in animals of a feeling of fear, nervousness, aggressiveness, gnashing of teeth, restlessness, timidity. The above symptoms occur in 98% of sick animals.
• The second type of nervous phenomena is characterized by the presence of movement disorders in sick animals: trotting movements, “raking in the front limbs”, “lowering” of the hind legs, raised tail
• In the third type of nervous phenomena, there is a violation of sensitivity, when in sick animals we note hyperesthesia with noise, touch and light. The duration of the disease is from several weeks to 12 months or more. The disease always ends in the death of the animal.

Pathological changes.

At autopsy of dead animals, characteristic pathoanatomical changes are either absent or mild.

Diagnosis.

Send to the laboratory for diagnostic tests:

– bovine brain after testing for rabies and other viral infections after the diagnosis was not confirmed;

– the brain of cattle from meat processing plants (0. 01% of slaughtered animals older than 3 years).

Pathological material (brain) is taken from animals with clinical signs of damage to the central nervous system). In this case, the brain for research must be taken from animals immediately after their slaughter or death.

Specific prophylaxis.

BSE does not produce either cellular or humoral immunity, so no vaccine has been developed in the world to date.

Treatment.

Treatment is ineffective, the prognosis for the disease is unfavorable.

Prevention.

The basis of prevention for prosperous countries is: preventing the importation of pedigree cattle, meat, canned food, by-products and semi-finished products, meat and bone meal, semen, embryos, technical fat, intestinal raw materials and other products and feeds of animal origin from ruminants; careful control over purchases of breeding stock and biological tissues, especially from disadvantaged countries; prohibition of feeding ruminants with meat-and-bone and bone meal from cattle and sheep.

If BSE is suspected, contact a veterinary clinic.

In order to prevent bovine spongiform encephalopathy, owners of susceptible animals must strictly comply with the requirements provided for in paragraph 7 of the Veterinary Rules for the implementation of preventive, diagnostic, restrictive and other measures, the establishment and lifting of quarantine and other restrictions aimed at preventing the spread and eliminating foci of large spongiform encephalopathy approved (hereinafter referred to as the Veterinary Rules), including paragraphs 6 and 7 of clause 7 of the Veterinary Rules regarding the incineration of waste from the slaughter of susceptible animals and the prohibition of feeding animals with meat and bone, bone meal, protein briquettes, as well as other feed and feed additives for animals containing ruminant proteins in their composition.

Mad cow disease

Bovine Spongiform Encephalopathy (BSE) or Mad cow disease and sheep and goats, chronic wasting disease in deer ( zombie deer), Creutzfeldt-Jakob disease in humans. Like all prion diseases, mad cow disease has a dangerously long incubation period and can manifest itself 5-8 years after infection.
Mad cow disease was first diagnosed in the UK in 1985, and it took some time to identify the disease. The infection of such a large number of livestock occurred due to the use of feed containing meat and bone meal with prion proteins.

The disease causes very serious economic damage. In the UK, about 4 million cattle were destroyed; dealt a serious economic and reputational blow to agriculture.
Thanks to the OIE’s stringent measures to control the use of feed of animal origin, the movement of animals and regular post-mortem diagnostics, mad cow disease has virtually disappeared. Sometimes isolated cases are recorded.

Spongiform encephalopathy prions have been shown to be transmitted to humans, causing Creutzfeldt-Jakob disease.

• Animal species: Cattle
• Disease category: Disease of the nervous system
• Anthroponosis: Yes
• 9009 0 Contagious: Yes
• Treated: No
• Natural focal: No
• Age groups: All

🔴 Species affected

Cattle. Cows get sick, bulls get infected less often.

🔴 Distribution

The disease is registered in almost all European countries, Asia, the Middle East, South and North America, Japan and Australia.

🔴 Etiology

Infection occurs through feed of animal origin: meat and bone meal, milk powder, etc. Especially dangerous are products and preparations containing tissues of the spinal cord and brain. There are no data on animal-to-animal transmission and very little data on infections transmitted from mother to fetus.
The disease is slow-moving, and the diseased animal is often slaughtered before clinical signs appear. According to the OIE, after infection, clinical signs appear, depending on the age and immunity of the animal, in the range from two to eight years.
Prion is resistant to heat and drying. This means that meat and milk from sick animals cannot be used as food or fed to other animals. Cases of infection of large felines in zoos have been reported when feeding meat from cows with mad cow disease.
Prions persist in the environment for a long time. There is evidence that prions live in water for about a year, and in soil for about three years. Even after passing through the digestive system of birds and mammals, prions retain their ability to remain infectious.
In diseased animals 100% death.

🔴 Pathogenesis

The origin, course and spread of the disease still require scientific research.
Mad cow disease is caused by a special type of protein called a prion. This protein has a self-sustaining altered form. When a defective protein enters the body, it causes the surrounding normal proteins to assume the same shape. This process is in the nature of a chain reaction and leads to the formation of large or cluster-like vacuoles in neuronal cells, and the brain tissue acquires a spongy structure. These changes are irreversible.

The uniqueness of the prion is that it does not have hereditary information in its structure and, if the configuration of the protein polypeptide chain matches, is able to overcome the species barrier. This is confirmed by an experiment on infecting mice with sheep prions (scrapie). It is assumed that the epidemic in the UK in 1985-1986 began with the purchase of a large batch of meat and bone meal, the raw material for which was infected scrapie sheep.

📌 There are two strains:

1. Classic mad cow disease. Transmitted through prion-contaminated food. It is assumed that young animals get sick, and then the disease slowly develops with irreversible consequences.
2. Atypical mad cow disease . Occurs spontaneously, and it is not yet known how infection occurs. Only old animals get sick. Infection through food in this case is excluded. It is assumed that in an old animal, the body ceases to maintain a constancy of the internal environment and proteins begin to fold into the form of a prion on their own.

Mad cow disease is listed by the OIE and all countries are required to report cases of the disease. Quarantine restrictions are imposed on the country: the export of livestock, meat, dairy and other products with additives of animal origin is prohibited.
Mad cow disease must be differentiated from encephalitis, rabies, tetanus, poisoning.

🔴 Clinical signs

• Wasting;
• Loss of productivity;
• Violation of coordination of movements;
• Hypersensitivity to sudden sounds and touch;
• Aggressive behavior;
• Tremor;
• Motor retardation.

🔴 Autopsy picture

No serious changes in the body are found at autopsy, except in cases of severe exhaustion.
Spongy lesions limited to the brain and spinal cord.
Fluid-filled cavities are clearly visible on a histological section of the brain tissue. Cells show single or multiple vacuoles.

🔴 Diagnosis

Diagnosis is based on clinical signs.
Currently, there is no test that can reliably confirm the presence of mad cow disease in vivo.
Diagnosis is postmortem based on histological examination of the medulla oblongata.
The diagnosis is confirmed by immunochemical or immunohistochemical detection of a specific prion protein in the medulla oblongata.