Description of prion infection
Prion diseases (otherwise also known as transmissible spongiform encelopatie, transmissible spongiform encefalopathy, TSE) is caused by the so-called. The prion protein (PrP). The normally fulfills unexplored feature in mammalian nerve cells. The essence of the disease is defective spatial configuration (conformation) of the protein. Pathologically arranged prion protein has moreover infect other prion, which also changes the conformation. Therefore spreads in a similar way as a virus. Prion Misfolded is resistant to enzymes that degrade normal prion. Nerve cell is then filled with pathological prion and dies. The brain is gradually changed in a spongy mass.Brain damage is a typical neurological symptoms. All prion diseases are incurable and fatal.
Prion diseases are species-specific. They mostly spread only between individuals of the same species. However, it was demonstrated interspecies transmission (interspecific overcoming barriers) has happened for scrapie (scrapie) in sheep with its transmission cow (BSE, mad cow disease).Transfer any prion disease from animals to humans, despite many suspect has not yet been demonstrated.
Part of the disease is familial occurrence (GSS, FFI, minority CJD). Part of the disease is transmissible (CJD, Kuru, BSE) and often occur unexpectedly, without the possibility of prevention.
Risk factors prion infection
For prion disease is a genetic perspective known risk factor in the presence of a given sequence of bases in a specific location of a gene encoding a prion.
Rizoko represent operations with prior contamination affected tissue and transplantation from patients with prion infection.
Unproven risk is the consumption of tissues of sick animals. The important feature here is the prion, that it can not be destroyed even by boiling. Withstand temperatures several times higher than the boiling point of water. Livestock itself without consuming products is certainly a risk.
The riskiest parts (most infectious) organism is affected brain (central nervous system), covers the brain, cornea (eye), blood and lymphoid organs. In muscle and other organs are likely to significantly lower the risk, infectivity but there probably is.
Prevention of prion infection
Prevention of hereditary and sporadic forms of prion infections exist. Experimentally, scientists are trying to find a substance that would stabilize the prion protein in physiological conformation, thus preventing its transition to pathological conformation.
For portable forms of the disease, it is important to avoid all modifiable risk factors. Among preventive measures, however, due to the way the spread of the disease should include actions such as discharge herds for the occurrence of a sick head of cattle.
Symptoms of prion infection
Human prion diseases
KURU
It occurred only in Papua New Guinea by cannibals who ate the brains of deceased. The disease is manifested by tremor (shaking kuru means), speech disorders, balance disorders (ataxia). After a few months, death occurs. When cannibalism was abandoned and disappeared KURU disease.
Creutzfeldt-Jakob disease, Creutzfeldt-Jakob disease
It is a rare disease that affects older people (usually 50-70 years), disease course is relatively fast, the death occurs in a few months (about a year) to develop symptoms. For certain disease is hereditary predisposition (the individual is more likely to get sick). For some this predisposition will further mutation in DNA, and disease in the offspring become familial (inherited). There were also cases iatrogeního transmission (caused by medical treatment), for example, in transplant corneal transplants in dura mater surgery and neurosurgery (contaminated instruments). Also can be transferred via the pituitary hormone made from the pituitary glands of deceased. It is probably also the possibility of transmission through blood. The disease manifests itself mainly movement disorders (Parkinson syndrom- damage to brain structures called the basal ganglia, responsible for programming motion) and stability (ataxia), tremor, impaired mental ability to dementia, behavioral change.
New variant Creutzfeldt-Jakob disease (nvCJD)
New variant CJD is a separate disease, which in many respects differs from classical CJD. There were still only a few dozen diseases worldwide. Affected were mainly younger people (around 30 years). Symptoms of the disease are depression, behavioral changes, impaired stability. Later, the patient loses the ability to move (up plegia paresis), stops talking and exhibits significant dementia.The process is slower than the classical CJD, death comes about two years after the first symptoms.
It is still not clarified associated with mad cow disease (BSE). There are reasons for accepting the conclusion that BSE overcome interspecific barrier and manifests itself in humans as nvCJD, but there are reasons not to. Neither option has not yet been fully confirmed nor refuted.
For connection nvCJD and BSE prevalence speaks first patients at the time of the spread of BSE.Also locus was identical (UK). Unclear is the way would pathological prion received from the tissue of a dead animal to neurons in the human brain. One theory is the involvement of the immune system, especially the so-called. Antigen-presenting cells and leukocytes.
Gerstmann Sträussler-Scheinker disease (GSS)
Hereditary disease that manifests dementia and problems with movement. It affects adults around 50 years. The illness leads to death after a few years.
Fatal familial insomnia (FFI)
It is an inherited disease causing insomnia and dementia. It affects adults around 50 years. Disease leads to death within two years of the first symptoms.
Animal prion diseases
The danger of prion disease in animals to humans is highly speculative (best describes the relationship issues of BSE and nvCJD). In animals manifested aggressiveness, movement disorders.
Scrapie (scrapie)
It affects goats and sheep. It is so far considered completely transferable to humans, but it is considered almost certain that overcame interspecific barrier and it became the BSE affecting cattle. This happened probably in feed manufacture of dead goats and sheep (feed-ingredient meat and bone meal). There have also been some suspicion of direct transmission to humans. One of the great examples of the deadly dementia incidence in the Slovak Republic in the widespread sheep.Most cases were diagnosed as Creutzfeldt-Jakob disease. Relationship has not been established.
Mad cow disease, Bovine spongioform encefalopathy (BSE)
He developed after the transition scrapie to cattle. It spread like scrapie bone meal. Therefore, a ban has been added bone meal in animal feed. The possible relationship of BSE and nvCJD been described above. For unexcreted risk of transmission to humans is issued and enjoy ban meat or other products from the contested cattle.
Transmissible mink encephalopathy, transmissible mink encephalopathy
The disease affects mink, interspecies transmission has not been confirmed.
Scrapie-like disease
The disease affects antelope, interspecies transmission has not been confirmed.
Feline Spongiform Encephalopathy
The disease affects cats, cougars, leopards.
Chronic disease waisting
The disease affects deer (deer, for example).
The treatment of prion infections
Treatment of prion diseases is not yet known.
Complications of prion infection
The gradual loss of mental ability to dementia, which is accompanied by other neurological deficits.Death in the majority of diseases within a few months.
Other names: Transmissible Spongiform encelopatie, Transmissible spongiform encefalopathy, TSE Creutzfeldt-Jakob disease, Creutzfeldt-Jakob disease, New variant Creutzfeldt-Jakob disease (nvCJD), mad cow disease, Bovine spongioform encefalopathy (BSE), scrapie, Scrapie, Kuru, Gerstmann Sträussler-Sc