Creutzfeldt–Jakob disease or CJD is a degenerative neurological disorder (brain disease) that is incurable and invariably fatal. The disease is at times called a human form of Mad Cow disease given the fact that Bovine spongiform encephalopathy is the cause of variant Creutzfeldt-Jakob disease in humans.
It is the most common among the types of transmissible spongiform encephalopathy found in humans. This means that the brain develops holes and takes on a sponge-like texture. This is caused by a type of infectious protein called a prion, prions are misfolded proteins which replicate by converting their properly folded counterparts.t is usually transmitted by eating contaminated beef. The disease is always fatal. There is no cure, and all treatments are experimental.
Creutzfeldt-Jakob disease captured public attention in the 1990s when individuals in the United Kingdom developed a form of the disease — variant CJD (vCJD) — after eating meat from diseased cattle. However, “classic” Creutzfeldt-Jakob disease has not been linked to contaminated beef.
Although serious, CJD is rare, and vCJD is the least common form. Worldwide, there is an estimated one case of Creutzfeldt-Jakob disease diagnosed per million people each year. In the United States there are about 200 cases per year. CJD usually appears in later life and runs a rapid course.
There are three major categories of CJD:
•Sporadic 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% of cases.
•Hereditary CJD: In hereditary CJD, the person has a family history of the disease and/or tests positive for a genetic mutation associated with CJD. About 5 to 10% of cases of CJD in the United States are hereditary.
•Acquired CJD: 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 a CJD patient. Since CJD was first described in 1920, fewer than 1% of cases have been acquired CJD.
CJD belongs to a family of human and animal diseases known as the transmissible spongiform encephalopathies (TSEs). Spongiform refers to the characteristic appearance of infected brains, which become filled with holes until they resemble sponges 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 in Papua New Guinea and has now almost disappeared. Fatal familial insomnia and GSS are extremely rare hereditary diseases, found in just a few families around the world. Other TSEs are found in specific kinds of animals. These include bovine spongiform encephalopathy (BSE), which is found in cows and often referred to as “mad cow” disease, scrapie, which affects sheep and goats, mink encephalopathy, and feline encephalopathy. Similar diseases including chronic wasting disease (CWD) occur in elk, deer, and exotic zoo animals.
Early symptoms are as follows:-
*Loss of interest in life
*Sudden jerky movements
As the disease progresses, mental symptoms worsen. Most people eventually lapse into a coma. Heart failure, respiratory failure, pneumonia or other infections are generally the cause of death. The disease usually runs its course in about seven months, although a few people may live up to one or two years after diagnosis
The symptoms of CJD are caused by the progressive death of the brain’s nerve cells, which is associated with the build-up of abnormal prion proteins forming amyloids. When brain tissue from a CJD patient is examined under a microscope, many tiny holes can be seen where whole areas of nerve cells have died. The word “spongiform” in “transmissible spongiform encephalopathies” refers to the sponge-like appearance of the brain tissue.
Transmissible spongiform encephalopathy diseases are caused by prions. The diseases are thus sometimes called prion diseases. Other prion diseases include Gerstmann–Sträussler–Scheinker syndrome (GSS), fatal familial insomnia (FFI) and kuru in humans, as well as bovine spongiform encephalopathy (BSE, commonly known as mad cow disease) in cattle, chronic wasting disease (CWD) in elk and deer, and scrapie in sheep. Alpers’ syndrome in infants is also thought to be a transmissible spongiform encephalopathy caused by a prion.
The prion that is believed to cause Creutzfeldt–Jakob exhibits at least two stable conformations. One, the native state, is water-soluble and present in healthy cells. As of 2007[update], its biological function is presumably in transmembrane transport or signaling. The other conformational state is very poorly water-soluble and readily forms protein aggregates.
People can also acquire CJD genetically through a mutation of the gene that codes for the prion protein (PRNP). This occurs in only 5–10% of all CJD cases.
The CJD prion is dangerous because it promotes refolding of native proteins into the diseased state,. The number of misfolded protein molecules will increase exponentially and the process leads to a large quantity of insoluble prions in affected cells. This mass of misfolded proteins disrupts cell function and causes cell death. Mutations in the gene for the prion protein can cause a misfolding of the dominantly alpha helical regions into beta pleated sheets. This change in conformation disables the ability of the protein to undergo digestion. Once the prion is transmitted, the defective proteins invade the brain and are produced in a self-sustaining feedback loop, causing exponential spread of the prion, leading to death within a few months, although a few patients have lived as long as two years.
Stanley B. Prusiner of the University of California, San Francisco (UCSF) was awarded the Nobel Prize in physiology or medicine in 1997 for his discovery of prions. For more than a decade, Yale University neuropathologist Laura Manuelidis has been challenging this explanation for the disease. In January 2007, she and her colleagues published an article in the Proceedings of the National Academy of Science and reported that they have found a virus-like particle (but without finding nucleic acids so far) in less than 10% of the cells a scrapie-infected cell line and in a mouse cell line infected by a human CJD agent.
The risk of CJD is low. The disease can’t be transmitted through coughing or sneezing, touching or sexual contact. The three ways it develops are:
*Spontaneously. Most people with classic CJD develop the disease for no apparent reason. CJD that occurs without explanation is termed spontaneous CJD or sporadic CJD and accounts for the majority of cases.
*By genetic mutation. In the United States, about 5 to 10 percent of people with CJD have a family history of the disease or test positive for a genetic mutation associated with CJD. This type is referred to as familial CJD.
*By contamination. A small number of people have developed CJD after being exposed to infected human tissue during a medical procedure, such as a cornea or skin transplant. Also, because standard sterilization methods do not destroy abnormal prions, a few people have developed CJD after undergoing brain surgery with contaminated instruments. Cases of CJD related to medical procedures are referred to as iatrogenic CJD. Variant CJD is linked primarily to eating beef infected with bovine spongiform encephalopathy (BSE), the medical term for mad cow disease.
Blood donor restrictions:
In 2004 a new report published in the Lancet medical journal showed that vCJD can be transmitted by blood transfusions. The finding alarmed healthcare officials because a large epidemic of the disease might arise in the near future. There is no test to determine if a blood donor is infected while in the latent phase of vCJD. In reaction to this report, the UK government banned anyone who had received a blood transfusion since January 1980 from donating blood. From 1999 there has been a ban in the UK for using UK blood to manufacture fractional products such as albumin.
Sperm donor restrictions:
In the U.S., the FDA has banned import of any donor sperm, motivated by a risk of Creutzfeldt–Jakob disease, inhibiting the once popular import of, for example, Scandinavian sperm. The risk, however, is not known, since artificial insemination has not been studied as a route of transmission. It is also not known whether prions cross the blood-testis barrier.
At present there is no single diagnostic test for CJD. When CJD is suspected, the first concern is to rule out treatable forms of dementia such as encephalitis (inflammation of the brain) or chronic meningitis. A neurological examination and spinal tap are often performed to rule out more common causes of dementia. An electroencephalogram (EEG) to record the brain’s electrical pattern can be particularly valuable because it shows a specific type of abnormality in CJD. Computerized tomography (CT) of the brain can help rule out the possibility that the symptoms result from other problems such as stroke or a brain tumor. Magnetic resonance imaging (MRI) brain scans also can reveal characteristic patterns of brain degeneration that can help diagnose CJD.
At present, the only sure 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 patient’s brain so that it can be examined by a neuropathologist. This procedure may be dangerous for the patient, 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 patient, 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. More tests for CJD are under development.
Most cases of Creutzfeldt-Jakob disease occur for unknown reasons, and no risk factors can be identified. However, a few factors seem to be associated with different kinds of CJD.
*Age. Sporadic CJD tends to develop later in life, usually around the age of 60. Onset of familial CJD occurs only slightly earlier. On the other hand, vCJD has affected people at a much younger age, usually in their late 20s.
*Genetics. People with familial CJD have a genetic mutation that causes the disease. The disease is inherited in an autosomal dominant fashion, which means you need to inherit only one copy of the mutated gene, from either parent, to develop the disease. If you have the mutation, the chance of passing it on to your children is 50 percent. Genetic analysis in people with iatrogenic and variant CJD suggest that inheriting identical copies of certain variants of the prion gene may predispose a person to developing CJD if exposed to contaminated tissue.
*Exposure to contaminated tissue. People who’ve received human growth hormone derived from human pituitary glands or who’ve had dura mater grafts may be at risk of iatrogenic CJD. The risk of contracting vCJD from eating contaminated beef is difficult to determine. In general, if countries are effectively implementing public health measures, the risk is very low. For example, in the United Kingdom the current estimated risk of acquiring vCJD from beef and beef products appears to be about 1 case in 10 billion servings. The risk from beef in other high-incidence countries is estimated to be very low, as well
As with other causes of dementia, Creutzfeldt-Jakob disease profoundly affects the mind as well as the body, although CJD and its variants usually progress much more rapidly. People with CJD usually withdraw from friends and family and eventually lose the ability to recognize or relate to them in any meaningful way. They also lose the ability to care for themselves, and many eventually slip into a coma. The disease ultimately is fatal.
Physical complications, all of which may become life-threatening, include:
There is no treatment that can cure or control CJD. Researchers have tested many drugs, including amantadine, steroids, interferon, acyclovir, antiviral agents, and antibiotics. However, none of these treatments has shown any consistent benefit. Current treatment for CJD is aimed at alleviating symptoms and making the patient as comfortable as possible.
There is no known way to prevent sporadic CJD from developing. If you have a family history of neurological disease, you may benefit from talking with a genetics counselor, who can help you sort through the risks associated with your particular situation.
If you’re caring for someone with CJD or vCJD, the National Institutes of Health recommend the following basic precautions:
*Wash your hands and exposed skin before eating, drinking or smoking.
*Protect your hands and face from exposure to the person’s blood or fluids.
*Cover cuts or wounds with waterproof bandages.
Preventing iatrogenic CJD:-
Hospitals and other medical institutions follow explicit policies to prevent iatrogenic CJD. These measures have included:
*Exclusive use of synthetic human growth hormone, rather than the kind derived from human pituitary glands
*Destruction of surgical instruments used on the brain or nervous tissue of someone with known or suspected CJD
*Single-use kits for spinal taps (lumbar punctures)
You could contract CJD from an organ transplant if the donor was in the incubation stage of the disease and not yet showing signs and symptoms. However, this scenario is very unlikely. The benefits obtained from an organ transplant are generally much greater than the risk of contracting CJD.
To help ensure the safety of the blood supply, people with a risk of exposure to CJD or vCJD aren’t eligible to donate blood. This includes people who:
*Have a biological relative who has been diagnosed with CJD
*Have received a dura mater brain graft
*Have received human growth hormone
*Spent a total of at least three months in the U.K. from 1980 to 1996
*Spent five years or more in France from 1980 to the present
*Received a blood transfusion in the U.K. between 1980 and the present
*Have injected bovine insulin at any time since 1980
Preventing vCJD :
The risk of contracting vCJD in the United States remains extremely low. So far, a total of three cases have been reported in the U.S. According to the Centers for Disease Control and Prevention, strong evidence suggests that these cases were acquired abroad — two in the United Kingdom and one in Saudi Arabia.
In the United Kingdom, where the majority of vCJD cases have occurred, fewer than 200 cases have been reported. After its first appearance in 1995, CJD incidence peaked between 1999 and 2000, and has been declining since.
Regulating potential sources of vCJD :
Most countries have taken steps to prevent BSE-infected tissue from entering the food supply, including tight restrictions on importation of cattle from countries where BSE is common; restrictions on animal feed; strict procedures for dealing with sick animals; surveillance and testing methods for tracking cattle health; and restrictions on which parts of cattle can be processed for food.
The risk of vCJD from the following sources is estimated to be extremely low:
*Vaccines. Some parts of cows, including blood, enzymes and amino acids, are used to grow the bacteria and viruses needed to make certain vaccines. Not all vaccines are grown in cattle parts, however, and the Food and Drug Administration (FDA) recommends that companies producing such vaccines use cattle parts only from low-risk countries. These recommendations apply to cosmetics as well. The FDA keeps a listing on its Web site of companies that use cattle from countries that aren’t classified as low-risk.
*Insulin. Insulin sold in the United States isn’t derived from cattle, but you’re allowed to import beef insulin from other countries if you follow specific guidelines. Because there’s no way to guarantee the safety of imported insulin, talk to your doctor about the best way to obtain insulin from sources outside the United States.
Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.
- Urine-derived fertility drugs may hike risk of Creutzfeldt-Jakob disease: study (calgaryherald.com)
- Fertility drugs may hike Creutzfeldt-Jakob risk: Study (canada.com)
- Some fertility drugs carry theoretical risk of deadly disease (ctv.ca)
- Brain-wasting prions found in fertility hormone (cbc.ca)
- Serum tau protein as a marker for the diagnosis of Creutzfeldt-Jakob disease (springerlink.com)
- Fast, accurate test to diagnose CJD developed (news.bioscholar.com)
- Prion disease diagnosis just got easier (scientificamerican.com)
- Creutzfeldt-Jakob disease: Breaking down the barrier (economist.com)
- vCJD blood test developed (telegraph.co.uk)
- vCJD blood test raises hopes of screening for human mad cow disease (dailymail.co.uk)
- First reliable blood test for vCJD raises hopes of screening for human form of mad cow disease (dailymail.co.uk)