Mad Cow Disease Bovine Spongiform Encephalitis (BSE)

What is mad cow disease?

BSE is commonly known as its official name is bovine spongiform encephalopathy (BSE).

(1) Mad cow disease is a fatal disease caused by infectious prion protein (also known as prion protein, Prion protein, also known as prion in habit).

(2) Mad cow disease can be transmitted.

(3) The principle of mad cow disease is still unclear. Possible mechanisms currently considered are:

1) Prion protein and PrPC protein on nerve cell membrane have the same amino acid sequence, but different folding methods.

2) The prion protein is not digested after being eaten, and because it has the same amino acid sequence as the normal protein in the body, it will not be cleared by the immune system.

3) However, when the prion is in contact with the normal protein in the body, it will be induced to be converted into the prion protein (the detailed mechanism is not yet clear). 

The protein cannot be broken down by the enzyme, so it accumulates in the brain to form plaque, which eventually leads to the central Nerve cells die and brain tissue is destroyed to form sponge-like vacuoles.

(4) The onset of mad cow disease is related to the consumption of meat and bone meal fed by Prion protein-infected cattle.

These feeds include but are not limited to sheep scrapie, mad cow disease and other sick animals, and their dead bodies are made into meat and bone meal.

What are the Causes of Mad Cow Disease?

1. Prions are abnormal proteins formed by certain glycoproteins (PrPc, which can be hydrolyzed by proteases) on the surface of normal host nerve cells after translation (PrPsc, which cannot be hydrolyzed by proteases, and the primary structure of PrPc and PrPsc Same but different secondary structure).

Prions can cause bovine spongiform encephalopathy, with a mortality rate of up to 100%, and can also cause human Kuru, Creutzfeldt-Jakob disease (CJD), Gehr-Sherman syndrome (GSS) and lethal families Eye loss, sheep pruritus in animals, infectious encephalopathy in mink, chronic atrophy of deer, etc.

2. The pathogen has strong resistance to ultraviolet rays, ionizing radiation, ultrasonic waves, non-ionic detergents, proteases and other physical and chemical factors. 

High temperature cannot completely inactivate them. Ethanol, formalin, hydrogen peroxide, phenol, etc. None can inactivate it. 

However, it can be inactivated by treatment with 2% to 5% sodium hypochlorite or 90% carbolic acid for 24 hours, and protein denaturants such as SDS, urea, and phenol can inactivate it.

What are BSE symptoms?

Symptoms 1. The symptoms of the cow are different after the cow has mad cow disease. Most of the sick cattle have changes in the central nervous system, abnormal behavior, irritability, excessive sensitivity to sound and touch, especially the head touch, unstable gait, often chaotic kick and even fall and twitch.

Symptom 2. Excessive excitement, panic, attack, hyperextension and hypersensitivity. In addition, he also showed ear and encephalopathy, twitching, repeated kicking, progressive ataxia, falling down, falling or even lying down, and finally died, with a course of 2 weeks to 0.5 years.

Symptom 3. This disease mostly occurs in adult cattle around 4 years old. Symptoms vary.

Most sick cows have changes in the central nervous system, abnormal behavior, irritability, excessive sensitivity to sound and touch, especially head touch, unstable gait, frequent kicks and even falls and convulsions.

Symptom 4. Tonic spasm occurs in the later stage, the stool is hard, the symmetry of the two ears is difficult to move, the heartbeat is slow, the respiratory rate increases, the weight decreases, the weight is extremely thin, and even death.

What is BSE infection?

BSE is mainly infected and spread by feeding cows with feed containing BSE pathogens. Sick cows have the highest levels of pathogens in the brain, spinal cord and other nerve tissues, and the risk of spreading mad cow disease is the greatest. They will not be spread by air or by contact with sick cattle.

1. Generally eat beef contaminated by mad cow disease, which may be infected. The typical clinical symptoms are dementia or nervous disorder, blurred vision, balance disorders, and muscle contraction. The patient eventually died of insanity.

2. All cattle are susceptible to mad cow disease, but the actual situation is that the vast majority of cases come from cows.

Cattle infection usually takes a long time to become ill after infection, mostly 2 to 8 years, so it is mainly caused by adult cattle.

 At present, there is no treatment for this disease, and there is no vaccine, and all infected cattle will die. Other animals such as sheep, cats, monkeys, tigers, and mink can also be infected with mad cow disease.

BSE can infect people, and after the infection, the person develops variant Yazi's disease, which cannot be treated and eventually leads to death. The main infection routes include food, medicines, and medical devices contaminated by the BSE pathogen.

What is the incubation period of mad cow disease?

It is understood that due to different types, the incubation period of BSE is different, generally between 2 and 30 years. 

The disease was first discovered in the United Kingdom in April 1985 and was named BSE in November 1986.

BSE is not only widespread in the UK, but cases have also been reported in many other countries and regions. The disease is now spreading globally.

The prevention and control measures currently adopted for BSE are:

(1) Prohibition of beef products in epidemic-prone areas:

 A comprehensive embargo is imposed on live cattle, cattle embryos, semen, milk products, by-products, etc. from countries and regions in BSE-endemic areas.

(2) Establish an epidemic report system:

 once a suspected BSE disease is found, it must be reported to the government's competent veterinary department in time.

(3) All cattle and other animals infected with BSE are slaughtered and safely destroyed.

(4) It is forbidden for humans and animals to consume animal feeds and internal organs that may contain vectors over 6 months of age.

(5) Strict feed processing regulations, prohibiting the use of meat and bone by-products such as cattle and sheep and other animals as feed additives for ruminants.

 

BSE and prion infection

1. Where was mad cow disease found? What is the spread?

BSE was first discovered in the United Kingdom, and now 26 countries in the world have found BSE in their own countries, spreading across Eurasia and North and South America. Britain is the most serious country, followed by Ireland and Portugal.

2. What will happen if the cow gets mad cow disease?

The incubation period of mad cow disease is about 4 to 6 years, and the course of disease is usually 14 to 90 days. 
The main symptoms of mad cow disease due to virus invasion of the nervous system are nervous system disorders, abnormal behavior, and uncoordinated movements. 
It's like a sponge. In the later stages of the disease, the weight of the sick cattle fell severely and eventually died.

3. Can humans get mad cow disease?

Humans will not get mad cow disease, but there is a human disease, the symptoms of variant Creutzfeldt-Jakob disease are very similar to mad cow disease.

Similarities include:

(1) Variant Creutzfeldt-Jakob disease is also caused by prion protein

(2) The main manifestation of variant Creutzfeldt-Jakob disease is also damage to the function of the nervous system. Prion proteins damage brain cells, and once brain cells are damaged, they cannot be regenerated. 

Therefore, the movement and memory functions of these brain cells will gradually appear to be impaired (Degenerative neuropathy).

(3) The lethal rate of variant Creutzfeldt-Jakob disease is 100%, and the incubation period can reach 15 years. Once the disease occurs, the patient will die within 12-18 months, and there is currently no effective treatment.

(4) Recent studies have found that the new variant Creutzfeldt-Jakob disease may be associated with mad cow disease infection, and related animal experiments also support the relationship between mad cow disease and variant Creutzfeldt-Jakob disease.

Variant Creutzfeldt-Jakob disease and mad cow disease currently have a lot of evidence to prove that it is caused by the same pathogen.

But there are other human diseases caused by other prion proteins (Prion protein), such as classic Yasinopathies, also caused by prion protein degenerative changes in the brain, but the disease has nothing to do with mad cow disease or variant Creutzfeldt-Jakob disease.

Other human diseases caused by Prion protein are currently known as Kuru, Fatal Familial Insomnia, and Gerstmann-Straussler- Scheinker Syndrome).

 

4. Is mad cow disease (or variant Creutzfeldt-Jakob disease) dangerous?

Although mad cow disease and variant Creutzfeldt-Jakob disease are so deadly, this disease is relatively rare. 

In the past 30 years since the discovery and determination of mad cow disease, according to the statistics of the World Health Organization, as of 2014, there were 226 people with global variant variant Creutzfeldt-Jakob disease.

Out of these, 175 cases occurred in the United Kingdom, one case occurred in Taiwan, and there are No case report of variant Creutzfeldt-Jakob disease.

The above 175 cases of WHO data are as of March 2011. The latest data is the US CDC data as of June 28, 2012. 

There are a total of 227 people with variant Creutzfeldt-Jakob disease worldwide, of which 176 cases are in the UK, 27 in France, 5 in Spain 4.

Also, there were 3 cases each in Ireland, the Netherlands and the United States, 2 cases each in Italy, Canada and Portugal, and 1 case each in Japan, Saudi Arabia and Taiwan.

  

5. How should mad cow disease be prevented?

Prevention methods for BSE include:

(1) All slaughtered and suspected sick animals are slaughtered, and the corpses are incinerated to prevent crazy beef from flowing into the market.

(2) The use of feed made from animal tissues (animal-derived feed), such as bone meal and meat and bone meal, is forbidden to feed ruminants such as cattle and sheep to block the route of infection.
 

6. I heard that BSE is epidemic abroad, are we safe now?

We are safe now. because:

(1) Up to now, no cases of BSE have been found in mainland China, and was approved by the World Animal Health Organization (OIE) in May 2014 to meet the negligible risk of BSE.

(2) The entry-exit inspection and quarantine department will not allow products that may be infected with BSE to flow into China:

1) A comprehensive ban on the import of beef and processed products from 23 BSE countries, including Britain, France, Germany, the United States and Japan;

2) Implement a comprehensive health quarantine, quality inspection and origin traceability system for imported live animals, meat and embryos to ensure the safety of imported animal products.

(3) Avoid the infection of cattle, sheep and other animals in our country: China completely prohibits the use of animal-derived feeds, such as bone meal, meat and bone meal, etc., and feeds made by animal organizations to feed cattle, sheep and other ruminants that may be infected with diseases. 

7. What should I pay attention to when eating beef?

Because the BSE virus is very resistant to the outside world, ordinary cooking heating can not kill the virus, so the most effective way to protect ourselves is not to eat meat and meat products that may be infected with BSE.

(1) If you are in Asia, you should polish your eyes when buying imported meat.

1) Only buy beef from a safe place of origin: Imported beef that meets safety standards in the domestic market mainly comes from countries in Oceania and South America.

These beef have been inspected layer by layer when they enter the  port, and the packaging has a clear mark on it, marking the meat, the types, sources, and inspection and quarantine certificates are guaranteed in terms of quality and safety.

2) Don't buy beef from dangerous places of origin: Japanese beef and European and American snowflake beef are all produced in the mad cow disease epidemic area recognized by the Ministry of Agriculture of China.

The state explicitly prohibits the import and sale of such beef. After several twists and turns, the safety and quality can not be guaranteed, or it is replaced by domestic beef, which is not true.

3) Don't be greedy when buying beef. Don't buy and consume beef and its products that are too low-priced.

These beef are likely to enter the market through illegal channels. They are not quarantined and their source is unknown. There is a great food safety risk.

4) If you have any questions when buying beef, you can ask the dealer to provide a quarantine certificate. If you cannot issue it, it means that you have encountered problem beef.

(2) If you are in Europe or Americas:

1) Don't be greedy when buying beef. Don't buy and consume beef and its products that are too low-priced.

These beef are likely to enter the market through illegal channels. They are not quarantined and their source is unknown. There is a great food safety risk.

2) For those who work, study and travel in the mad cow disease epidemic area: They should choose a restaurant that has standardized management and meets hygienic standards.

3) For those who work, study and travel in areas where mad cow disease has broken out: 
Pay attention to avoid eating bone-in beef, beef offal and minced meat products as much as possible.

Because cattle's brain, eyes, spinal cord, skull and lymph nodes are the sites with higher risk of mad cow disease pollution, the above ingredients may be mixed in the ground meat during processing, and the ground meat is often processed into sausages and other products.

8. Where should I go to pay special attention to mad cow disease?

(1) The Ministry of Health of China stipulates that the countries affected by BSE include:

United Kingdom, France, United States, Japan, Belgium, Italy, Germany, Netherlands, Switzerland, Denmark, Oman, Ireland, Sweden, Czech Republic, Greece, Poland, Finland, Canada, Luxembourg, Spain, Portugal, Austria, Israel, Slovakia, Ecuador, Liechtenstein.

(2) Brazil currently evaluates OIE as a negligible country for the risk of BSE. China has lifted the ban on the import of Brazilian beef in July 2014.

(3) Taiwan evaluates the controllable risk of BSE in OIE. 

9. What are the prevention methods for variant Creutzfeldt-Jakob disease?

Variant Creutzfeldt-Jakob disease can be thought to be related to exposure to mad cows and consumption of beef, guts and their products.

The best way to prevent this is to slaughter diseased cows and nearby cows that are likely to be infected and destroy the carcasses properly, while avoiding the use of bone meal to feed livestock in animal husbandry.

Prion is a protein structure, which cannot be effectively inactivated by the normal cooking temperature, so it cannot be killed by post-processing methods.

10. What are the diagnostic criteria for variant Creutzfeldt-Jakob disease?

Diagnostic criteria include: Dementia with rapid progression (progressive dementia) is the main symptom, and may be accompanied by muscle twitching (myoclonus), eye movements (visual impairment), unstable walking (cerebellar disorder), and general muscle function Obstacles (dysfunction of the vertebral body and vertebral extracorporeal system), aphasia and non-intermittent movement inability (motile silence)

(1) The following conditions can be used as a diagnosis, but a pathological diagnosis must be made after surgical biopsy:

1) Extensive amyloid changes appear in the brain and cerebellum, surrounded by many vacuoles.

2) Extensive sponge-like changes appear in the brain and cerebellum. Immunohistochemical staining proves that this is Prion protein.

(2) The following cases can be regarded as suspected cases:

1) The age or age of death is less than 55 years old.

2) The onset has mental symptoms and / or persistent pain.

3) Dementia, with a development time of not less than 4 months after the onset of the disease. At least 2 of the following 5 neurological symptoms: poor coordination, myoclonus, chorea, hyperreflexia, or visual symptoms (if there is persistent pain , Then neurological symptoms are not required).

4) Normal or abnormal electroencephalogram, but it is different from that of classic Creutzfeldt-Jakob disease.

5) The onset period exceeds 6 months.

6) The patient's routine examination does not support other non-creutzfeldt-Jakob disease.

7) Have not been treated with cadaver-derived pituitary growth hormone or dura mater transplantation.

8) Immediate relatives do not have classic Creutzfeldt-Jakob disease, or the patient does not have prion protein (Prion protein) gene mutation.

11. What is the treatment for variant Creutzfeldt-Jakob disease?

The following content is from "Dr. Lilac" www.dxy.com

At present, there is no targeted treatment for variant Creutzfeldt-Jakob disease, and generally only symptomatic treatment and intensive care.

12. Can variant Creutzfeldt-Jakob disease be transmitted from person to person?

Variant Creutzfeldt-Jakob disease has not been found to be transmitted from person to person.

A similar disease, Kuru disease, is spread from person to person. In some indigenous tribes in Oceania, there is the custom of eating the offal of the loved ones. Among these tribes, there is an epidemic of Kuru disease.

 

Author's Bio

Dr. Shawna Reason

Name: Shawna Reason

Education: MBBS, MD

Occupation: Medical Doctor / Virologist 

Specialization: Medical Science, Micro Biology / Virology, Natural Treatment

Experience: 15 Years as a Medical Practitioner

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