This is a terminal condition and there is currently no specific treatment for the disease.

As of 2017, there was no cure for BSE; some of the symptoms like twitching can be managed but otherwise treatment is palliative care.

As of 2015 there was no cure for CJD; some of the symptoms like twitching can be managed but otherwise treatment is palliative care.

There is no cure for GSS, nor is there any known treatment to slow the progression of the disease. However, therapies and medication are aimed at treating or slowing down the effects of the symptoms. Their goal is to try to improve the patient's quality of life as much as possible. Despite there being no cure for GSS, it is possible to undergo testing for the presence of the underlying genetic mutation. Testing for GSS involves a blood and DNA examination in order to attempt to detect the mutated gene at certain codons. If the genetic mutation is present, the patient will eventually be afflicted by GSS, and, due to the genetic nature of the disease, the offspring of the patient are predisposed to a higher risk of inheriting the mutation.

A ban on feeding meat and bone meal to cattle has resulted in a strong reduction in cases in countries where the disease was present. In disease-free countries, control relies on import control, feeding regulations, and surveillance measures.

In UK and US slaughterhouses, the brain, spinal cord, trigeminal ganglia, intestines, eyes, and tonsils from cattle are classified as specified risk materials, and must be disposed of appropriately.

An enhanced BSE-related feed ban is in effect in both the United States and Canada to help improve prevention and elimination of BSE.

There is no cure or treatment for GSS. It can, however, be identified through genetic testing. GSS is the slowest to progress among human prion diseases. Duration of illness can range from 3 months to 13 years, with an average duration of 5 or 6 years.

An experimental treatment was given to a Northern Irish teenager, Jonathan Simms, beginning in January 2003. The medication, called pentosan polysulphate (PPS) and used to treat interstitial cystitis, is infused into the patient's lateral ventricle within the brain. PPS does not seem to stop the disease from progressing, and both brain function and tissue continue to be lost. However, the treatment is alleged to slow the progression of the otherwise untreatable disease, and may have contributed to the longer than expected survival of the seven patients studied. Simms died in 2011. The CJD Therapy Advisory Group to the UK Health Departments advises that data are not sufficient to support claims that pentosan polysulphate is an effective treatment and suggests that further research in animal models is appropriate. A 2007 review of the treatment of 26 patients with PPS finds no proof of efficacy because of the lack of accepted objective criteria.

Scientists have investigated using RNA interference to slow the progression of scrapie in mice. The RNA blocks production of the protein that the CJD process transforms into prions. This research is unlikely to lead to a human therapy for many years.

Both amphotericin B and doxorubicin have been investigated as potentially effective against CJD, but as yet there is no strong evidence that either drug is effective in stopping the disease. Further study has been taken with other medical drugs, but none are effective. However, anticonvulsants and anxiolytic agents, such as valproate or a benzodiazepine, may be administered to relieve associated symptoms.

Scientists from the University of California, San Francisco are currently running a treatment trial for sporadic CJD using quinacrine, a medicine originally created for malaria. Pilot studies showed quinacrine permanently cleared abnormal prion proteins from cell cultures, but results have not yet been published on their clinical study. The efficacy of quinacrine was also assessed in a rigorous clinical trial in the UK and the results were published in Lancet Neurology,

and concluded that quinacrine had no measurable effect on the clinical course of CJD.

In a 2013 paper published in the Proceedings of the National Academy of Sciences, scientists from The Scripps Research Institute reported that Astemizole, a medication approved for human use, has been found to have anti-prion activity and may lead to a treatment for Creutzfeldt–Jakob disease.

Research is focused on better ways to monitor disease in the wild, live animal diagnostic tests, developing vaccines, better ways to dispose of animals who died from the disease and to decontaminate the environment, where prions can persist in soils, and better ways to monitor the food supply. Deer harvesting and management issues are intertwined.

Ataxia was observed to last for about 8 weeks in the affected animals. The ultimate result is death of the infected animals.

It is expected that there will be no new cases of progressive inflammatory neuropathy since the process of aerosolizing the pig brains has been discontinued at all pork processing facilities.

Treatment varies according to the type and severity of the encephalopathy. Anticonvulsants may be prescribed to reduce or halt any seizures. Changes to diet and nutritional supplements may help some patients. In severe cases, dialysis or organ replacement surgery may be needed.

Sympathomimetic drugs can increase motivation, cognition, motor performance and alertness in patients with encephalopathy caused by brain injury, chronic infections, strokes, brain tumors.

Transmissible spongiform encephalopathies (TSEs), also known as prion diseases, are a group of progressive, invariably fatal, conditions that affect the brain (encephalopathies) and nervous system of many animals, including humans. According to the most widespread hypothesis, they are transmitted by prions, though some other data suggest an involvement of a "Spiroplasma" infection. Mental and physical abilities deteriorate and myriad tiny holes appear in the cortex causing it to appear like a sponge (hence spongiform) when brain tissue obtained at autopsy is examined under a microscope. The disorders cause impairment of brain function, including memory changes, personality changes and problems with movement that worsen chronically.

Prion diseases of humans include Creutzfeldt–Jakob disease—which has four main forms, the sporadic (sCJD), the hereditary/familiar (fCJD), the iatrogenic (iCJD) and the variant form (vCJD)—Gerstmann–Sträussler–Scheinker syndrome, fatal familial insomnia, kuru, and the recently discovered variably protease-sensitive prionopathy. These conditions form a spectrum of diseases with overlapping signs and symptoms. TSEs in non-human mammals include scrapie in sheep, bovine spongiform encephalopathy (BSE)—popularly known as 'mad cow's disease'—in cattle and chronic wasting disease (CWD) in deer and elk. The variant form of Creutzfeldt–Jakob disease is caused by exposure to bovine spongiform encephalopathy prions.

Unlike other kinds of infectious disease, which are spread by agents with a DNA or RNA genome (such as virus or bacteria), the infectious agent in TSEs is believed to be a prion, thus being composed solely of protein material. Misshapen prion proteins carry the disease between individuals and cause deterioration of the brain. TSEs are unique diseases in that their aetiology may be genetic, sporadic, or infectious via ingestion of infected foodstuffs and via iatrogenic means (e.g., blood transfusion). Most TSEs are sporadic and occur in an animal with no prion protein mutation. Inherited TSE occurs in animals carrying a rare mutant prion allele, which expresses prion proteins that contort by themselves into the disease-causing conformation. Transmission occurs when healthy animals consume tainted tissues from others with the disease. In the 1980s and 1990s, bovine spongiform encephalopathy (BSE) spread in cattle in an epidemic fashion. This occurred because cattle were fed the processed remains of other cattle, a practice now banned in many countries. In turn, consumption (by humans) of bovine-derived foodstuff which contained prion-contaminated tissues resulted in an outbreak of the variant form of Creutzfeldt–Jakob disease in the 1990s and 2000s.

Prions cannot be transmitted through the air or through touching or most other forms of casual contact. However, they may be transmitted through contact with infected tissue, body fluids, or contaminated medical instruments. Normal sterilization procedures such as boiling or irradiating materials fail to render prions non-infective.

Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) of mule deer, white-tailed deer, elk (or "wapiti"), moose, and reindeer. As of 2016, CWD had only been found in members of the deer family. First recognized as a clinical "wasting" syndrome in 1967 in mule deer in a wildlife research facility in northern Colorado, USA, it was identified as a TSE in 1978 and has spread to free-ranging and captive populations in 23 US states and two Canadian provinces. CWD is typified by chronic weight loss leading to death. No relationship is known between CWD and any other TSE of animals or people.

Although reports in the popular press have been made of humans being affected by CWD, a study by the Centers for Disease Control and Prevention suggests, "[m]ore epidemiologic and laboratory studies are needed to monitor the possibility of such transmissions".

The epidemiological study further concluded, "[a]s a precaution, hunters should avoid eating deer and elk tissues known to harbor the CWD agent (e.g., brain, spinal cord, eyes, spleen, tonsils, lymph nodes) from areas where CWD has been identified".

No treatment is available for affected sheep.

A test performed by sampling a small amount of lymphatic tissue from the third eyelid is now available.

In the United Kingdom, the government has put in place a National Scrapie Plan, which encourages breeding from sheep that are genetically more resistant to scrapie. This is intended to eventually reduce the incidence of the disease in the UK sheep population. Scrapie occurs in Europe and North America, but to date, Australia and New Zealand (both major sheep-producing countries) are scrapie-free.

Breeds such as Cheviot and Suffolk are more susceptible to scrapie than other breeds. Specifically, this is determined by the genes coding for the naturally occurring prion proteins. The most resistant sheep have a double set of "ARR" alleles, while sheep with the "VRQ" allele are the most susceptible. A simple blood test reveals the allele of the sheep, and many countries are actively breeding away the "VRQ" allele.

Out of fear of BSE, many European countries banned some traditional sheep or goat products made without removing the spinal cord, such as smalahove and smokie.

In 2010, a team from New York described detection of PrP even when initially present at only one part in a hundred billion (10) in brain tissue. The method combines amplification with a novel technology called surround optical fiber immunoassay and some specific antibodies against PrP. The technique allowed detection of PrP after many fewer cycles of conversion than others have achieved, substantially reducing the possibility of artefacts, as well as speeding up the assay. The researchers also tested their method on blood samples from apparently healthy sheep that went on to develop scrapie. The animals' brains were analysed once any symptoms became apparent. They could therefore compare results from brain tissue and blood taken once the animals exhibited symptoms of the diseases, with blood obtained earlier in the animals' lives, and from uninfected animals. The results showed very clearly that PrP could be detected in the blood of animals long before the symptoms appeared. After further development and testing, this method could be of great value in surveillance as a blood- or urine-based screening test for scrapie.

Variant Creutzfeldt–Jakob disease (vCJD) or new variant Creutzfeldt–Jakob disease (nvCJD) is a transmissible spongiform encephalopathy which was identified in 1996 by the National CJD Surveillance Unit in Edinburgh, Scotland. It is always fatal and is caused by prions, which are mis-folded proteins. Over 170 cases of vCJD have been recorded in the United Kingdom, and around 30 cases in the rest of the world. The fact that the epidemiology of the disease coincided with an epidemic of bovine spongiform encephalopathy led to the hypothesis that consumption of BSE-infected beef caused the disease. It is a different disease from Sporadic and Familial Creutzfeldt–Jakob disease, though it is believed to be caused by the same pathogenic agent, a mis-folded protein, known as a prion.

Despite the consumption of contaminated beef in the UK being reckoned to be quite high, vCJD has infected a comparatively small cohort of people. One explanation for this can be found in the genetics of patients with the disease. The human PRNP protein which is subverted in prion disease can occur with either methionine or valine at amino acid 129, without any apparent difference in normal function. Of the overall Caucasian population, about 40% have two methionine-containing alleles, 10% have two valine-containing alleles, and the other 50% are heterozygous at this position. Only a single vCJD patient tested was found to be heterozygous; most of those affected had two copies of the methionine-containing form. Additionally, for unknown reasons, those affected are generally under the age of 40. It is not yet known whether those unaffected are actually immune or only have a longer incubation period until symptoms appear.

There continues to be a very practical problem with diagnosis of prion diseases, including BSE and CJD. They have an incubation period of months to decades during which there are no symptoms, even though the pathway of converting the normal brain PrP protein into the toxic, disease-related PrP form has started. At present, there is virtually no way to detect PrP reliably except by examining the brain using neuropathological and immunohistochemical methods after death. Accumulation of the abnormally folded PrP form of the PrP protein is a characteristic of the disease, but it is present at very low levels in easily accessible body fluids like blood or urine. Researchers have tried to develop methods to measure PrP, but there are still no fully accepted methods for use in materials such as blood.

In 2010, a team from New York described detection of PrP even when initially present at only one part in a hundred billion (10) in brain tissue. The method combines amplification with a novel technology called Surround Optical Fiber Immunoassay (SOFIA) and some specific antibodies against PrP. After amplifying and then concentrating any PrP, the samples are labelled with a fluorescent dye using an antibody for specificity and then finally loaded into a micro-capillary tube. This tube is placed in a specially constructed apparatus so that it is totally surrounded by optical fibres to capture all light emitted once the dye is excited using a laser. The technique allowed detection of PrP after many fewer cycles of conversion than others have achieved, substantially reducing the possibility of artefacts, as well as speeding up the assay. The researchers also tested their method on blood samples from apparently healthy sheep that went on to develop scrapie. The animals’ brains were analysed once any symptoms became apparent. The researchers could therefore compare results from brain tissue and blood taken once the animals exhibited symptoms of the diseases, with blood obtained earlier in the animals’ lives, and from uninfected animals. The results showed very clearly that PrP could be detected in the blood of animals long before the symptoms appeared.

Recent research from the University of Toronto and Caprion Pharmaceuticals has discovered one possible avenue that might lead to quicker diagnosis, a vaccine or possibly even treatment for prion diseases. The abnormally folded proteins that cause the disease have been found to expose a side chain of amino acids that the properly folded protein does not expose. Antibodies specifically coded to this side-chain amino acid sequence have been found to stimulate an immune response to the abnormal prions and leave the normal proteins intact.

Another idea involves using custom peptide sequences. Since some research suggests prions aggregate by forming beta barrel structures, work done "in vitro" has shown that peptides made up of beta barrel-incompatible amino acids can help break up accumulations of prion.

A third idea concerns genetic therapy, whereby the gene for encoding protease-resistant protein is considered to be an error in several species, and therefore something to be inhibited.

Transmissible mink encephalopathy (TME) is a rare sporadic disease that affects the central nervous system of ranch-raised mink. It is classified as a transmissible spongiform encephalopathy, believed to be caused by proteins called prions. This disease is only known to affect adult mink.

A slow virus is a virus, or a viruslike agent, etiologically associated with a disease, having a long incubation period of months to years and then a gradual onset of symptoms which progress slowly but irreversibly and terminate in a severe compromised state or, more commonly, death.

A slow virus disease is a disease that, after an extended period of latency, follows a slow, progressive course spanning months to years, frequently involving the central nervous system and ultimately leading to death. Examples include the Visna-Maedi virus, in the genus Lentivirus (family Retroviridae), that causes encephalitis and chronic pneumonitis in sheep, and subacute sclerosing panencephalitis which is apparently caused by the measles virus, as well as Paget's Disease of Bone (Osteitis Deformans) which is associated with paramyxoviridae, especially RSV and Rubeola (Measles).

Scrapie is a fatal, degenerative disease that affects the nervous systems of sheep and goats. It is one of several transmissible spongiform encephalopathies (TSEs), which are related to bovine spongiform encephalopathy (BSE or "mad cow disease") and chronic wasting disease of deer. Like other spongiform encephalopathies, scrapie is caused by a prion. Scrapie has been known since 1732, and does not appear to be transmissible to humans.

The name scrapie is derived from one of the clinical signs of the condition, wherein affected animals will compulsively scrape off their fleeces against rocks, trees, or fences. The disease apparently causes an itching sensation in the animals. Other clinical signs include excessive lip smacking, altered gaits, and convulsive collapse.

Scrapie is infectious and transmissible among conspecifics, so one of the most common ways to contain it (since it is incurable) is to quarantine and destroy those affected. However, scrapie tends to persist in flocks and can also arise apparently spontaneously in flocks that have not previously had cases of the disease. The mechanism of transmission between animals and other aspects of the biology of the disease are only poorly understood, and these are active areas of research. Recent studies suggest prions may be spread through urine and persist in the environment for decades.

Scrapie usually affects sheep around three to five years of age. The potential for transmission at birth and from contact with placental tissues is apparent. No evidence indicates scrapie is infectious to humans.

In October 2007 an astute medical interpreter noticed similar neurological symptoms being reported by Spanish-speaking patients seeking treatment from different physicians at the Austin Medical Center, in Austin, Minnesota. Not only did these patients share similar neurological symptoms, they also worked at the same pork processing plant. Dr. Daniel LaChance, a physician at both the Austin Medical Center and the Mayo Clinic in nearby Rochester, Minnesota, was notified. He launched a request to area physicians to refer other patients with similar symptoms to him. The Minnesota Department of Health (MDH) was notified and began an investigation into the "outbreak." The MDH identified workers from two other pork processing plants in Indiana and Nebraska who also had parallel neurological complaints. Several agencies including the Occupational Safety and Health Administration (OSHA) and the Center for Disease Control and Prevention (CDC) were brought in to assist. Simultaneously investigations were conducted to rule out contagious disease, to locate the source or carrier, and to identify what exactly was causing these workers to develop these symptoms.

Removal from exposure was the first line of treatment. Due to progressive sensory loss and weakness, immunotherapy was often required. These treatments included intravenous methylprednisolone, oral prednisone, azathioprine, and/or immunoglobulin. All 24 patients improved, including 7 who received no treatment and 17 who required immunotherapy.

Exotic ungulate encephalopathy is a transmissible spongiform encephalopathy (TSE), or prion disease, identified in infected organs of zoo animals. This subgroup of the TSEs in captive animals was identified in zoo animals in Great Britain including species of greater kudu, nyala, gemsbok, the common eland, Arabian and Scimitar Oryx, an Ankole-Watusi cow, and an American bison. Studies indicate that transmission likely occurred via the consumption of feed supplemented with meat and bone meal, although some animals died after the British ban on ground offal in animal feed. All animals died during the 1990s, with the last death occurring in 1998.

Treatment is mainly for the symptoms that toxic encephalopathy brings upon victims, varying depending on how severe the case is. Diet changes and nutritional supplements may help some patients. To reduce or halt seizures, anticonvulsants may be prescribed. Dialysis or organ replacement surgery may be needed in some severe cases.

Management of affected individuals consists of immediate removal from exposure to the toxic substance(s), treatment of the common clinical manifestation of depression if present, and counselling for the provision of life strategies to help cope with the potentially debilitating condition.

Every infectious agent is different, but in general, slow viruses:

Additionally, the immune system seems to plays a limited role, or no role, in protection from these slow viruses. This may be in part because the host has acclimated to the virus, or more likely because the host must be immunocompromised in order for many of these slow virus infections to emerge, so the immune system is at a disadvantage from the start.

Treating the underlying cause of the disorder may improve or reverse symptoms. However, in some cases, the encephalopathy may cause permanent structural changes and irreversible damage to the brain. These permanent deficits can be considered a form of stable dementia. Some encephalopathies can be fatal.

This illness has a minimum incubation period of 7 months with a maximum of 12 months. This disease results in mortality of adult animals.

Clinical signs of TME include the characteristic behavioural changes such as confusion, loss of cleanliness, and aimless circling. An affected animal shows signs of weight loss, might develop matted fur, hindquarter ataxia, and its tail arched over its back. Seizures may very rarely occur. Near-death stages include the animal showing signs of drowsiness and unresponsiveness.

Currently, no tests are available to detect signs of this illness in live animals. However, veterinary pathologists can confirm this illness by microscopic examination of the brain tissue in animals suspected to have died of this disease, where they expect to detect areas of distinct sponge-like formations, or by the identification of the prion protein in these tissue samples.