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Government must do more to reduce risk of vCJD infection

Posted Jul 24 2014 2:33pm
Government must do more to reduce risk of vCJD infection

 
24 July 2014 .

 
More action is needed to ensure that variant Creutzfeldt-Jakob disease (vCJD), the human form of bovine spongiform encephalopathy (BSE), is not inadvertently transmitted from person-to-person through medical procedures, the Science and Technology Committee has today warned.

 
Report: After the storm? UK blood safety and the risk of variant Creutzfeldt-Jakob Disease Report: After the storm? UK blood safety and the risk of variant Creutzfeldt-Jakob Disease (PDF) Inquiry: Blood, tissue and organ screening Science and Technology Committee

 
Andrew Miller MP, Chair of the Science and Technology Committee, said:

 
"Variant CJD is a terrible disease and thankfully cases are now rare. However, research suggests that around one in 2,000 of us could be unknowingly carrying the infectious prions responsible for the condition. This raises the worrying prospect that these prions could be transmitted to others via blood transfusions and other medical procedures.

 
There remains significant uncertainty about the magnitude of this risk and the Government therefore claims to be taking a precautionary approach. But our inquiry has shown that its attitude towards vCJD today is far less precautionary than it was in the past. Indeed, recent policy seems to have been driven less by precaution than by economic prudence and a hope that the storm has now passed. This optimism is not supported by the available evidence."

 
Transmission via surgery

 
Contaminated surgical instruments are a potential source of ‘prion transmission’—the mechanism by which both CJD and vCJD are spread. However, evidence to the inquiry suggests that Government guidance on preventing prion transmission may not have been fully implemented across the NHS. According to figures published by Public Health England, 43 incidents occurred between January 2010 and March 2013 in which surgical patients may have been exposed to CJD as a result of infection control guidance not being properly followed. In many cases this was because the infected patient was not diagnosed with CJD at the time they underwent surgery and enhanced infection control was therefore not deemed necessary. However, in the light of the long period during which people may be 'silently' infected with CJD, the Committee recommends that the Government take a more precautionary approach to mitigating this risk.

 
The Committee says that Ministers must work with the National Institute of Health and Care Excellence (NICE) and the Advisory Committee on Dangerous Pathogens to assess the extent to which precautions are being taken in hospitals and come up with a plan to improve implementation if preliminary findings prove that compliance is unsatisfactory. The Committee also recommends greater support for technologies potentially capable of more effectively decontaminating surgical instruments.

 
Andrew Miller MP:

 
"Prions bind strongly to metal surfaces and the Government acknowledges that standard decontamination treatments are ineffective in removing prions from surgical instruments.

 
It is known that CJD can be transmitted through the use of contaminated surgical instruments but the Government's response to this threat has been insufficient. It has failed to support development of a technology capable of eliminating this risk and instead chooses to rely on guidance which it knows is only partially effective. And evidence suggests that this guidance is not even followed in some parts of the NHS."

 
Transmission via blood transfusion

 
Evidence presented to the inquiry suggests that we cannot be confident that prions are not present in the blood supply. To date, there have only been four confirmed cases in which vCJD is known to have been transmitted via blood transfusion. All of the implicated transfusions are thought to have occurred in the 1990s; however, concerns were raised during the inquiry that asymptomatic prion transmission could still be widespread and could potentially lead to further cases of transfusion-transmitted vCJD in the future.

 
Andrew Miller MP:

 
"We know that vCJD can be transmitted via blood transfusion because it has happened in the past. And we have reason to believe that prions may still be present in the blood supply, so there is a chance that it could happen again. However, in the absence of a reliable vCJD blood screening test, we are unable to discard those donations that might be dangerous.

 
In our view, the Government could be doing more to help mitigate this risk of infection. Key steps would be for it to reduce uncertainty by supporting relevant research, for example by using the prototype blood test developed by the MRC prion unit in a large-scale study to better understand the rate of ‘silent infection’ across the UK donor pool. The Minister stressed that a lot of public money had already gone into the development of this test and she appeared reluctant to commit more. But the money already invested is a sunk cost and to cut off support now, when the task appears to be nearing completion, would be a false economy."

 
In the vast majority of cases the benefits of receiving a transfusion will far outweigh the risk of acquiring a transfusion-transmitted infection. However, the Committee is warning against complacency and is urging UK Blood Services to remain vigilant to the threat posed by vCJD, as well as other blood-borne pathogens such as emerging viruses. In the past it has often taken multiple cases of infection before threats have been recognised and mitigated.

 
The report recommends that the Government commission a full assessment of the risks currently faced by the UK blood supply so that knowledge gaps can be filled and additional risk reduction measures and technologies developed as appropriate.

 
Background

 
A prion is an infectious agent comprised of protein folded into an abnormal form. Prions are responsible for a family of fatal brain diseases known as transmissible spongiform encephalopathies (TSEs). Examples include livestock diseases such as bovine spongiform encephalopathy (BSE) and scrapie and, in humans, Creutzfeldt-Jakob Disease (CJD).

 
CJD is a debilitating neurodegenerative disease caused by a build-up of abnormal protein in the brain. Symptoms of CJD are similar to those of dementia and include loss of balance, coordination and mobility, loss of memory, slurred speech, personality change and progressive loss of brain function. CJD is invariably fatal and most people die within a year of first experiencing symptoms.

 
Prior to the mid-1990s, three types of “classical” CJD had been characterised: an inherited form that runs in families (typically 5–10 cases per year in the UK) an acquired form, transmitted through contact with human tissue contaminated with prions (2–3 per year) a sporadic form of unknown cause, historically responsible for the majority of cases (50–100 per year)

 
Following the BSE epidemic of the late 1980s and 1990s, the first cases of a new form of CJD were identified. Variant Creutzfeldt-Jakob Disease (vCJD) shared some symptoms with classical CJD but tended to affect younger people and led to a longer period of illness before death. Primary transmission was thought to be caused by exposure to BSE-infected material, such as contaminated meat. Since vCJD was first identified in 1995 it has been attributed to 177 UK deaths, the majority occurring between 1996 and 2003.

 
http://www.parliament.uk/business/committees/committees-a-z/commons-select/science-and-technology-committee/news/report-blood-tissue-and-organ-screening/

 

 *** 1: J Neurol Neurosurg Psychiatry 1994 Jun;57(6):757-8

 
Transmission of Creutzfeldt-Jakob disease to a chimpanzee by electrodes contaminated during neurosurgery.

 

Gibbs CJ Jr, Asher DM, Kobrine A, Amyx HL, Sulima MP, Gajdusek DC.

 

Laboratory of Central Nervous System Studies, National Institute of

 

Neurological Disorders and Stroke, National Institutes of Health,

 

Bethesda, MD 20892.

 

Stereotactic multicontact electrodes used to probe the cerebral cortex of a middle aged woman with progressive dementia were previously implicated in the accidental transmission of Creutzfeldt-Jakob disease (CJD) to two younger patients. The diagnoses of CJD have been confirmed for all three cases. More than two years after their last use in humans, after three cleanings and repeated sterilisation in ethanol and formaldehyde vapour, the electrodes were implanted in the cortex of a chimpanzee. Eighteen months later the animal became ill with CJD. This finding serves to re-emphasise the potential danger posed by reuse of instruments contaminated with the agents of spongiform encephalopathies, even after scrupulous attempts to clean them.

 

PMID: 8006664 [PubMed - indexed for MEDLINE]

 


 

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Prion Infected Meat-and-Bone Meal Is Still Infectious after Biodiesel Production

 


 

Detection of protease-resistant cervid prion protein in water from a CWD-endemic area

 


 

A Quantitative Assessment of the Amount of Prion Diverted to Category 1 Materials and Wastewater During Processing

 


 

Rapid assessment of bovine spongiform encephalopathy prion inactivation by heat treatment in yellow grease produced in the industrial manufacturing process of meat and bone meals

 


 

PPo4-4:

 

Survival and Limited Spread of TSE Infectivity after Burial

 


 

*** The potential impact of prion diseases on human health was greatly magnified by the recognition that interspecies transfer of BSE to humans by beef ingestion resulted in vCJD. While changes in animal feed constituents and slaughter practices appear to have curtailed vCJD, there is concern that CWD of free-ranging deer and elk in the U.S. might also cross the species barrier. Thus, consuming venison could be a source of human prion disease. Whether BSE and CWD represent interspecies scrapie transfer or are newly arisen prion diseases is unknown. Therefore, the possibility of transmission of prion disease through other food animals cannot be ruled out. There is evidence that vCJD can be transmitted through blood transfusion. There is likely a pool of unknown size of asymptomatic individuals infected with vCJD, and there may be asymptomatic individuals infected with the CWD equivalent. These circumstances represent a potential threat to blood, blood products, and plasma supplies.

 


 

snip...see more here ;

 

Wednesday, July 23, 2014

 

After the storm? UK blood safety and the risk of variant Creutzfeldt-Jakob Disease

 


 

 

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