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
Andrew Miller MP:
"Prions bind strongly to metal surfaces and the Government acknowledges
that standard decontamination treatments are ineffective in removing prions from
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
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
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
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.
*** 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]
New studies on the heat resistance of hamster-adapted scrapie agent:
Threshold survival after ashing at 600°C suggests an inorganic template of
Prion Infected Meat-and-Bone Meal Is Still Infectious after Biodiesel
Detection of protease-resistant cervid prion protein in water from a
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
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