What is Mad Cow Disease?
Mad cow disease, also called bovine spongiform encephalitis (BSE), is a life threatening disease which affects the brains of cows. It can be passed onto humans via the consumption of infected meat.
The human version of this disease is called variant Creutzfeldt-Jakob disease (vCJD). Up to December 2017, only 231 people worldwide are known to have contracted this disease. Of those, the majority of cases were in people who lived in the United Kingdom.
There were only four reported cases in the US, and it is likely these people contracted the infection when traveling or living overseas. (1)
Symptoms
Mad cow disease affects the central nervous system of the animal and gets worse over time.
Thought to be the result of an abnormal protein which forms in the brain called a prion, the exact causes are not fully understood.
The first sign that a cow has this disease is a lack of coordination. They could have trouble getting up walking. They can also become violent and nervous; hence the name, mad cow disease.
This disease has an incubation period of about four to six years. There is no vaccine available and no preventative treatment. This disease is fatal; the usual life expectancy from the onset of symptoms being two weeks to six months.
There are currently no tests available to determine whether a live cow has this disease. It is only seen on examination of the brain after death. (2)
This disease has only recently been discovered, coming to light in the 1980s. It is thought to have spread to cattle from an abnormal prion disease in sheep, called scrapie. Bone and meat mix from infected sheep and fed to cows contained a mutated version of an abnormal prion. (3)
How Mad Cow Disease Affects Humans
The human form of the disease, caused by ingestion of meat infected with BSE, is variant Creutzfeldt-Jakob disease. This is also the result of abnormal proteins in the brain (prions).
Proteins made from amino acids help cells in our body to function. They start out as a string of acids which then form a three-dimensional shape by folding themselves.
By doing this, they are able to perform functions in the cells which are useful to the body. Prion proteins are in cells throughout the body, but the majority are in the nerve and brain cells.
While their exact function remains unknown, prion proteins might enable the transportation of messages between brain cells.
Sometimes they don’t fold themselves correctly and the body cannot use them. In this case, the body recycles the misfolded prions.
However, misfolded prion proteins are able to accumulate in the brain, causing others to misfold. When this happens, brain cells might die and release more prions which infect other cells in the brain.
Over time, groups of brain cells die and misfolded prions deposit in the brain, causing plaques. These prion protein infections also result in small holes forming in the brain, giving it a sponge-like appearance.
The brain becomes damaged and unable to function efficiently, eventually leading to death. The infected prions are able to survive in the spinal cord and brain for a long time after death.
There are four types of disease (CJD) caused by abnormal prions. The one that manifests as a result of mad cow disease is variant Creutzfeldt-Jakob disease (vCJD).
This disease is caused by the same strain of abnormal prions, thought to have spread from cattle fed on an infected meat and bone mix.
The contaminated beef entered the human food chain when it was used in various meat products, like beef burgers. In 1996, the use of meat and bone mix was made illegal. Controls were put in place to prevent mad cow disease re-entering the human food chain.
Not everyone who consumes infected meat develops vCJD. It is suggested that one in every 2000 people in the UK could be infected with vCJD but show no symptoms at the present time.
The cases identified happened in people infected with a particular prion strain (MM). This affected the way in which the body produced some amino acids.
Transmission of this disease can also happen via a blood transfusion. While very rare, procedures are in place to try and prevent it happening. (4, 5)
The symptoms associated with variant Creutzfeldt-Jakob disease differ from other forms of CJD. The average age at time of death for people with vCJD is 28 years old and the duration of the disease is between 13 and 14 months.
People with vCJD present with psychological symptoms first, followed a few months later by neurological symptoms.
Psychological Symptoms
Depression, which is quite severe, is a symptom of this condition. We all feel fed up and unhappy from time to time. When someone has depression, they are persistently sad, and these feelings last much longer than a few days.
People will also feel despairing, they will have lost all hope and feel anguished, desperate and unhappy. They will begin to spend less time with family and friends and generally withdraw from the world around them.
Feelings of anxiety will be common and a person might become increasingly irritable.
It is also likely they will suffer from insomnia. The knock-on effect means the person is tired and irritable during the day and finds it hard to concentrate.
As the disease progresses, memory loss will become apparent. This can be quite severe. A person will become very confused and often feel agitated. Concentration will become increasingly difficult.
Individuals might become aggressive and paranoid. They could start presenting with inappropriate and unusual emotional responses to people and situations.
Their appetite might lessen and they could start losing weight.
Neurological Symptoms
Neurological symptoms associated with vCJD tend to develop after the psychological signs.
They could manifest as difficulty walking, accompanied by issues with balance and coordination.
Speech may be slurred and a person might have problems with vision. These include seeing double, and on occasion, hearing and seeing things which don’t exist (hallucinations).
Dizziness is another result of damage to the brain as a result of the condition. Pins and needles or numbness may be felt in any area of the body.
As the disease progresses, the person will lose coordination altogether. This affects many functions, including speaking, walking and balance. Their muscles can start to twitch and spasm.
Difficulties swallowing (dysphagia) will be experienced. Loss of control of the bladder and bowels are other common symptoms.
Eventually, the person will lose the ability to see or speak and won’t be able to make any voluntary movements.
During the final stages of this disease, they will be unable to do anything for themselves. They will also become totally unaware of their surroundings. They will be bedridden and need constant care, losing the ability to speak and communicate. (6)
It is worth noting that neither variant Creutzfeldt-Jakob disease, or mad cow disease, are contagious. You cannot catch either from being near a cow or a person with the condition. Mad cow disease also cannot be contracted from dairy products or milk. (7)
Stages
There are no stages associated with mad cow disease and variable Creutzfeldt-Jakob disease.
It is progressive, with symptoms presenting for between 13 and 14 months from onset. (8)
Treatment
There is currently no known cure or treatment that can manage this condition. Treatment is aimed at making the sufferer comfortable and managing and easing the associated symptoms.
There are drugs which can help relieve muscle spasms and twitches, such as sodium valproate and clonazepam. Opiate based drugs can help control pain, if necessary.
When the disease progresses to its final stages, fluids and foods can be administered intravenously. (9)
FAQ
What is mad cow disease? Mad cow disease, also called bovine spongiform encephalitis (BSE), is a life threatening disease which affects the brains of cows. It can be passed onto humans via the consumption of infected meat. The human form of the disease is called variant Creutzfeldt-Jakob disease (vCJD).
What are the signs of mad cow disease? The signs of this disease are both psychological and neurological. The symptoms are similar to those of Alzheimer’s, including dementia and loss of speech, sight and movement.
How do you develop mad cow disease? Human variant Creutzfeldt-Jakob disease is contracted following consumption of meat infected with BSE.
How are you diagnosed for mad cow disease? The human form of this disease (vCJD) is diagnosed via an EEG, a test which records the electrical patterns of the brain. An MRI scan or tests on a sample of spinal fluid might also indicate vCJD. Definitive diagnosis can only be determined by an autopsy after death. (10)
What is the best treatment for mad cow disease? There is, unfortunately, no treatment for this condition, other than palliative care.
What are the long term complications of mad cow disease? This disease is fatal.
Is mad cow disease considered a disability? Social security benefits might be paid when a person can no longer work. (11)
Is there a cure for mad cow disease? There is at the present time, no cure for this disease.
Is mad cow disease life threatening? This disease is life threatening.
Summary
Mad cow disease, also called bovine spongiform encephalitis (BSE), is a life threatening disease which affects the brains of cows. It can be passed onto humans via the consumption of infected meat.
The human version of this disease is called variant Creutzfeldt-Jakob disease (vCJD).
There is no known cure for this rare condition. Treatment is aimed at making a person comfortable as they near the end of life.