Department of Health

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Protecting the public

Variant CJD is an unusual disease because its infectious agent (prion) is a variant of a protein found in the body.

The precise mechanisms that trigger the development of disease remain unclear, but it appears that in certain circumstances exposure to the abnormal protein - for example by eating the BSE agent - prompts the build-up of prions in the brain and in some lymph tissue. Levels of exposure required for the disease to develop are not known but certain tissues, for example brain and lymph materials, are more likely to transmit the disease. It has never been transmitted from person-to-person by conventional means such as coughing and sneezing, close personal contact, or sexual intercourse. Apart from ingestion in some cattle products, there may be other routes of transmission such as exposure to blood, and these need to be safeguarded (see later sections).

Independent scientific advice

The Spongiform Encephalopathy Advisory Committee (SEAC) is appointed by ministers and sponsored jointly by the Department for Environment, Food and Rural Affairs (Defra), the Department of Health (DH) and the Food Standards Agency (FSA). Its role is to provide independent expert scientific advice to the government on transmissible spongiform encephalopathies such as BSE, CJD and scrapie.

SEAC's remit is wide-ranging and covers public health, food safety and animal health issues. Its advice informs government policy and guidelines to protect against vCJD transmission. The Committee was formed in 1990, before the discovery of vCJD, and its terms of reference are as follows:

'To provide scientifically based advice to the Department for Environment, Food and Rural Affairs, the Department of Health, devolved administrations, and the Food Standards Agency on matters relating to spongiform encephalopathies, taking account of the remits of other bodies with related responsibilities'.

Medically induced transmission

There have been cases where sporadic CJD has been transmitted unintentionally from person to person through the use of contaminated surgical instruments. This is known as iatrogenic (medically induced) CJD and it is very rare: only a few cases of CJD have been recorded as arising from re-using neurosurgical instruments that had been previously used in brain surgery on a CJD patient. Before 1985 there have also been cases where it was transmitted from injections of human growth hormone.

Both these examples occurred before it was realised that CJD could be transmitted in this way. Since then, all surgical instruments used on known CJD patients must be destroyed, instruments used on suspect cases are quarantined, and human growth hormone injections are made from a synthetic substitute.

Other action was taken to protect against transmission in surgical instruments. In 1998 prion protein was discovered in the appendix of a patient who subsequently developed vCJD. Following this, a joint working group made up of SEAC and the Advisory Committee on Dangerous Pathogens (ACDP) reviewed all previous guidance on CJD, resulting in new guidance being issued to the NHS in April 1998. It emphasised the importance of cleaning and sterilising instruments and set out the procedures for handling instruments used on patients with suspected CJD or vCJD.

Two further health service circulars were issued in August 1999, introducing new guidance on 'single use' surgery instruments and controls for the decontamination of medical devices. In January 2001, it was announced that £200m had been allocated for improvement of decontamination facilities and £25m for the provision of disposable, single-use instruments for tonsillectomy. A report was published at the end of that year showing that significant progress had been made.

Tonsillectomy instruments

However, surgeons reported problems with disposable instruments, particularly the diathermy, which is used to stop bleeding. Single-use instruments for tonsillectomy were therefore withdrawn in December 2001. To understand the range of factors that might contribute to post-operative bleeding, the Department of Health is funding an audit of tonsillectomy procedures in England by the British Association of Otorhinolaryngologists - Head and Neck Surgeons (BAO-HNS).

In early 2004, interim results from this audit showed that complication rates were higher following surgery with single-use instruments and very high when a particular type of diathermy was used. As a result, the Chief Medical Officer asked the National Institute for Clinical Excellence (NICE) to issue urgent guidance to the NHS on the use of single-use instruments and diathermy. This was issued in March 2004. The guidance also asked surgeons to collect information as part of the ongoing national audit, to inform a future definitive ruling on the issue.

NICE was also asked by the Chief Medical Officers of England, Scotland, Wales and Northern Ireland to develop guidance on best practice in technique and choice of instruments for reducing any possible risks of variant vCJD transmission for a wider range of surgical procedures. Consultations took place in the autumn of 2004 and definitive quidance is planned for May 2006.

In May 2004 the Chief Medical Officer issued additional guidance for the quarantine of surgical instruments following brain biopsies. This is to reduce the risk of possible onward transmission of sporadic CJD via the surgical instruments used in the biopsy.

CJD Incidents Panel

During 1999 and 2000, the Department of Health was alerted to situations where surgery had been carried out on patients who subsequently went on to develop CJD. In August 2000 the DH set up an incidents panel to advise NHS on public health implications of such cases.

The panel's terms of reference are: "To assist all those bodies responsible for the provision and delivery of healthcare to decide on the most appropriate action to take to handle incidents involving potential transmission of Creutzfeldt-Jakob Disease and variant CJD between patients through clinical interventions, including via surgical instruments, tissues, organs and blood and to keep the relevant devolved administrations informed."

Safety of medicines, vaccines and cosmetics

Many medicines, vaccines and cosmetics are made using bovine material. It is therefore necessary to protect the public against the theoretical risk of transmission by these means.

In 1988, guidelines were issued for the pharmaceutical industry on the use of animal-derived materials in the manufacture of medicinal products. These have been amended over the years to reflect emerging scientific knowledge about BSE. Since the guidelines became law, manufacturers have been required to demonstrate to the licensing regulatory agency that medicines comply with the latest version of the guidelines.

More recently the European Medicines Agency (EMEA) issued guidelines that manufacturers of medicinal products for supply in the EU are required to comply with the latest version of the agency's Committee for Medicinal Products for Human Use (CHMP) "Note for guidance on minimising the risk of transmitting animal spongiform encephalopathy agents via human and veterinary products".

The Committee on Safety of Medicines (CSM) has undertaken several separate reviews of many aspects of vaccine safety since 2000, including an assessment of the BSE transmission risk. It has found no source for TSE-related concern in the safety of vaccines used in this country. It also carried out a review of the issue for health ministers.

The situation is continuously being monitored both in the UK and within Europe.

Blood-borne transmission

There have been two possible cases of vCJD transmission through blood transfusion. Details of the first case were announced by the Secretary of State for Health in a statement on 17 December 2003, explicitly acknowledging a possible link.

Since 1997 a range of precautionary measures have been put in place to safeguard the blood supply against the possible risk vCJD, outlined below. These measures are constantly re-evaluated as new evidence emerges.

Withdrawal and recall of any blood components, plasma products or tissues obtained from any individual who later develops vCJD (December 1997).

Sourcing of plasma from outside the UK (October 1998) and preparation of products such as clotting factors from plasma imported from the United States (late 1999).

Removal of white blood cells (leucodepletion) from all blood components (Autumn 1999).

Import of fresh frozen plasma from the United States for neo-natal patients born on or after 1 January, 1996 (Spring 2004) and for older children as appropriate.

Not accepting donations from people who have received a blood transfusion since January 1980 (April 2004), including apheresis donors (August 2004), and those who are unsure whether or not they have received a blood transfusion (August 2004)

The risk of vCJD transmission through plasma products is uncertain. However, a selected group of patients was notified in September 2004 that it was considered to be 'at risk', following a risk assessment exercise for blood plasma products undertaken by the Health Protection Agency. Patients were informed for public health purposes. This is a further precautionary measure based on the recommendations of the expert CJD Incidents Panel.

Recognising that there is a balance to be struck between sensible and effective risk reduction measures against an unknown risk, and the need to maintain sufficient supplies of blood to meet the needs of patients, the Chief Medical Officers of England, Wales, Scotland and Northern Ireland held a conference on Better Blood Transfusion in October 2001.

The NHS was given information about better blood transfusion and the appropriate use of blood. Guidance was issued on 4 July 2002 for action by NHS Trusts on "Better Blood Transfusion: appropriate use of blood". A programme of action was set out to make blood transfusion safer, avoid unnecessary use of blood in clinical practice and provide better information to patients and the public about blood transfusion.

The Chief Medical Officer also made reform of blood use a priority in his Annual Report 2003, and again in his Annual Report 2004.

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