Bovine Spongiform Encephalopathy (BSE)- Mad Cow Disease

Bovine spongiform encephalopathy is a fatal neurodegenerative disease that can be passed from person to person. It is brought on by proteinaceous agents and causes neuronal loss, spongiform lesions, astrogliosis, and the cessation of inflammatory responses.

Due to the fact that it affects both humans and animals, particularly domestic cattle like dairy cows, it is also known as "prion sickness" or "mad cow illness."

• The infectious protein is thought to be a typical host prion protein that has undergone a post-translational alteration to alter its structure.
• The altered protein becomes resistant to enzyme deactivation and inactivation.
• Brain inflammation, rabies, louping illness, and cerebral listeriosis are a few of the often causing degenerative disorders of the brain.
• In the UK, BSE cases peaked at more than 300 cases per week in 1993, and since then, the disease has become a major public health concern.
• Scrapie (host: sheep and goat), Chronic Wasting Disease (deer, elk, and moose), Transmissible Mink Encephalopathy (mink), Feline Spongiform Encephalopathy (domestic cats and wild lions, pumas, cheetahs, and tigers), and Exotic Ungulate Encephalopathy are other prion disease categories (antelopes).
• Fatal familiar insomania, Gertmann-Straussler-Scheinker disease, Creutzfeldt-Jakob disease, and Variant Humans contract the Creutzfeldt-Jakob disease by eating certain foods.

Table of Contents

• Sources and causes of contamination of Bovine Spongiform Encephalopathy (BSE)
• Pathogenic mechanism of Bovine Spongiform Encephalopathy (BSE)
• Signs and symptoms of Bovine Spongiform Encephalopathy (BSE)
• Epidemiology of Bovine Spongiform Encephalopathy (BSE)
• Diagnosis of Bovine Spongiform Encephalopathy (BSE)
• Treatment and Vaccination
• Prevention and control measures of Bovine Spongiform Encephalopathy (BSE)

Sources and causes of contamination of Bovine Spongiform Encephalopathy (BSE)

• The prion, a misfolded protein that causes neurological disease and is resistant to extreme heat and pressure, is the cause of bovine spongiform encephalopathy.
• The degraded protein converts an alpha-helical structure into a beta-sheet and then generates a short chain that kills cells.
• Multiple cell deaths result in lesions in the brain, which can then develop into other neurological disorders and, ultimately, death.
• When a healthy animal comes into contact with a contaminated food supply, particularly polluted meat, the disease is spread.
• It is thought that many animals become infected after eating tainted meat and bone meal (MBM).
• By feeding meat and bone meal to young calves and using scrapie-infected sheep products, other cattle become affected.
• Variant Creutzfeldt-Jakob disease (vCJD), which is thought to be transmitted to humans when they become infected, may be brought on by contaminated meat from slaughtered and deceased animals, particularly the brain, spinal cord, and digestive system.

Pathogenic mechanism of Bovine Spongiform Encephalopathy (BSE)

• When BSE agents are consumed in sick meat and bone meal, infection can happen orally or intracerebrally.
• When the BSE agent enters the digestive tract, it uses specialised macromolecule transporter M-cells to pass through the tonsil and gut epithelium and the mucosal barrier.
• The ability of the BSE agent to enter the digestive tract is also improved by proteins like ferritin and direct uptake by dendritic cells.
• It then gathers and multiplies in the gut-associated lymphoid tissues (GALT), primarily in the tonsil, ileum, and jejunum.
• The enteric nervous system, part of the gut's neural tissue, is initially infected by the BSE agent (ENS).
• The ENS agent gets to the brain, cervical spinal cord, cerebral cortex, cerebellum, hippocampus, and basal nuclei via efferent neural pathways (parasympathetic and sympathetic).
• The infection eventually spreads across the entire brain, leading to a disorder that degenerates the brain.
• Bovine spongiform encephalopathy in cattle results in recognisable lesions in the brain and spinal cord that induce astrocytic hypertrophy and hyperplasia, as well as neuronal vacuolation, degeneration, and loss.

Signs and symptoms of Bovine Spongiform Encephalopathy (BSE)

• Early signs of the illness include worry and anxiety, which are comparable to the person's cow-driving habit suffering from herdsmen exhibiting behavioural changes.
• Neurological infections progress slowly and have an impact on mental health as well as sensory alterations and hypersensitivity to sound and touch.
• Movement and posture abnormalities, low head carriage, tremors, hindlimb ataxia, decreased milk production in mammals, decreased cud-chewing, slowed heart rate, and eventually terminal recumbency and death are all signs of abnormality.
• Depending on the frequency and severity of the sickness, the incubation time might range from seven days to more than a year.
• By reducing environmental factors like increased stress during travel, the severity of the infection can be altered.
• On young cattle that are under 20 months old, the BSE agent has not been found.

Epidemiology of Bovine Spongiform Encephalopathy (BSE)

• The majority of cases have been recorded from the United Kingdom, where there had at one point been 37,280 afflicted cattle.
• The rearing of cattle and the consumption of meat-and-bone meals then contributed to the disease's spread to other European nations.
• Due to various techniques of rearing cattle, dairy cows are more impacted than beef cattle. As a result, after birth, dairy calves are divided and fed artificial milk.
• Cats, eland, gemsbok, oryx, pumas, cheetahs, ocelots, and rhesus monkeys are just a few of the other creatures that have the disease.
• After the prohibition on food and feed was put into effect, the number of BSE cases decreased by 40% annually.
• Japan is the only country outside of Europe with 36 BSE cases that are not imported, prompting the creation of a governmental Food Safety Commission in 2003.
• If the illness is discovered and no risk is created, other nations such as the United States, Canada, the Falkland Islands, and the Sultanate of Oman slay and destroy, and the threat is eliminated.

Diagnosis of Bovine Spongiform Encephalopathy (BSE)

• Clinical diagnosis is 85% reliable, and microscopic examination of the brain is used to confirm illness.
• Prions associated with bovine spongiform encephalopathy are estimated via animal bioassays.
• The prion protein (PrP) antigen is discovered using the enzyme-linked immunosorbent test (ELISA), which reacts with the antibody. Additionally, it can find anti-pathogen antibodies.
• To examine pathological alterations using light microscopy, histological examination of tissue fixed in paraffin and stained with hematoxylin and eosin is performed.
• The presence of prion protein deposits is identified via immunohistochemistry. The staining pattern of infection is seen using secondary antibodies that specifically target particular PrP epitopes.
• They also distinguish between distinct prions strains and pre-treat the afflicted tissues.
• By using antibodies bound to prion proteins that divide based on their rate of migration, the western immunoblotting approach detects the antigen.
• After gel electrophoresis, three separate bands may be seen; the highest band is diglycosylated, meaning it contains two sugar molecules; the middle band is monoglycosylated; and the lowest band, known as unglycosylated, contains no sugar molecules.
• To distinguish between isolates and strains, researchers use the unglycosylated band. Contrarily, mono- and di-glycosylated bands are also employed to differentiate isolates, albeit interpretation varies depending on the laboratory procedures.

Treatment and Vaccination

There are no known cures or vaccines for bovine spongiform encephalopathy at this time.

Prevention and control measures of Bovine Spongiform Encephalopathy (BSE)

• The prevention of bovine spongiform encephalopathy can be achieved by eliminating all meat and other products obtained from cattle from cow feed.
• By limiting the import and export of beef, meat-and-bone meal, live cattle, and other cattle products, it can help prevent the spread of illness from one nation to another.
• The specified risk body parts, such as the brain, spinal cord, tonsils, intestines, eyes, and trigeminal ganglia, are safely disposed of in slaughterhouses in the US and UK.
• International import and export regulations are currently in place to prevent the BSE prion from getting into the human food supply chain.
• The relevant authority must be notified when a BSE agent is discovered so they can burn the entire contaminated animal body.
• Laboratory personnel should adhere to safety regulations and measures when handling infectious materials, sampling, and testing.