Diagnostic Laboratories
Routine laboratory work
4.37 A range of laboratory tests may be required for the clinical management of known, suspect or at risk patients, for example, routine biochemical, haematological or microbiological analyses. The classification of the agent of CJD has been discussed earlier and, because it is classified in Hazard Group 3, all clinical specimens from known, suspect or at risk patients should be handled at Containment Level 3. However, the option of derogation does apply and, based on local risk assessment, certain Containment Level 3 precautions can be dispensed with.
Samples from at risk patients
4.38 From information about the tissue distribution of infectivity of TSEs, it is thought that samples from the CNS present a greater risk of exposure to the agent of CJD than other samples. For routine clinical analysis not involving deliberate intention to work with the agent of CJD, samples from at risk patients that are not from the CNS, and are not known to be contaminated with CNS, can generally be handled in the same way as other clinical samples, providing that the risks have been assessed as required by the COSHH Regulations. In general, blood, urine, faecal specimens and swabs can be collected, processed and handled as for any other patient. General guidance on the handling and disposal of clinical specimens has been issued by the Health Services Advisory Committee (1992) and is currently being updated.
Samples from known or suspect patients
4.39 When handling specimens from known or suspect patients, or CNS specimens from at risk patients, particular care should be taken to avoid accidental inoculation or injury, for example, when preparing samples for microscopy or culture. Wherever practicable, disposable equipment should be used (cell counting chambers etc.) and items contaminated by the specimens should be destroyed by incineration, or else autoclaved or disinfected to the required standard (see Annex B). Special arrangements may be needed to minimise any residual contamination of equipment. Where manual analysis using disposable equipment is not feasible, and automated equipment is to be used, the potential for residual contamination must be considered and be dealt with appropriately before equipment is serviced. Where stringent decontamination procedures are inappropriate, as in the case of microscopes, the equipment should be cleaned and regularly maintained to avoid accumulation of potentially contaminated debris.
Neuropathology specimens
4.40 The general precautions above for handling specimens apply for similar work with brain and neural biopsy specimens from known, suspect or at risk patients. However, as infectivity may be concentrated in such CNS samples, they present a greater risk of exposure, and additional precautionary measures are appropriate. It may be more appropriate for such specimens to be handled in a specialist neuropathology laboratory or centre. Where there are facilities locally, limited histological processing can be undertaken with care by staff taking suitable precautions and wearing the appropriate protective clothing etc. For the specialist laboratory handling large numbers of samples, additional precautions may be necessary because of the possibility of increased residual contamination.
4.41 All preparations of brain and neural tissue from known, suspect or at risk patients for diagnosis and confirmation must be treated as potentially infectious, and handled in the laboratory at Containment Level 3 (subject to derogation, see Part 3). The use of disposable non permeable material is a convenient way of preventing contamination of the work surface. This covering and all washings, other waste material and protective clothing should be disposed of by incineration.
4.42 For optimal fixation of whole brain for general histopathology purposes, standard formalin should be used. However, formalin-fixed TSE tissue retains infectivity for long periods, if not indefinitely, and should be handled with the same precautions as fresh material. Similarly, tissue for electron microscopy fixed in glutaraldehyde retains its infectivity. This is of equal importance when handling archive material stored in fixative, blocks or as mounted slides. As evidenced by work with both CJD and scrapie, formalin-fixed TSE tissues can be decontaminated largely, if not completely, by formic acid treatment. However, as the full extent of the efficacy of the formic acid treatment is still uncertain, histological preparations of known TSE brain and neural tissue should be regarded as potentially infective, and special care taken to avoid breaking the microscope slides or similar accidents during which penetrating injuries could occur. Once tissue blocks are fixed and acid-treated, sections can be cut on a standard microtome (using a disposable knife) and processed as usual. Debris (wax shavings) from section cutting should be contained and disposed of by incineration.
National and international transport of pathology specimens
4.43 Pathology specimens are subject to detailed national transport guidelines, directed towards ensuring that these goods are carried under optimum conditions for the safety of persons, property and environment. Carriage by rail or road in the UK is covered by the Classification, Packaging and Labelling of Dangerous Goods for Carriage by Road or Rail Regulations (1994). The transport of specimens from known, suspect or at risk patients should fulfil these requirements, and no other specific precautions need be taken.
4.44 The transportation of pathology samples, or deceased patients, by air from the UKneeds to comply with the International Air Transport Association (IATA) Restricted Articles Regulations, and any additional requirements of the individual carriers. Documentation required by the IATA includes a Shipper’s Certificate for Restricted Articles, which requires content, nature and quantity of infectious material to be disclosed.
Community Healthcare
4.45 When caring for known, suspect or at risk patients in the community, the principles outlined in the section on hospital care are equally applicable. Either in hospital or in community healthcare, standard infection control procedures will minimise the risk of infection transmission, not only to the care-givers, but also to members of the surrounding community and population in general.
4.46 Clinical waste generated as a result of community care-based treatment, e.g. swabs and sharps, should be handled as for any clinical waste, and be disposed of by incineration. Guidance on the handling of clinical waste has been published and a new edition is due in 1998 (see bibliography).
4.47 Spillages of body fluids or waste material should be handled as previously recommended (see paragraph 4.16).
4.48 Used or fouled bed linen (i.e. contaminated with body fluids or excreta) should be removed from the bed and washed and dried in accordance with convention (HSG 1995). Provided that care is taken, bed linen is unlikely to represent an infection risk; however to further reduce the risk, gloves should be worn and hands washed and dried after contact. No further handling or processing requirements are necessary.
4.49 In the event that a known, suspect or at risk patient becomes pregnant, no particular precautions need to be taken during the pregnancy other than normal ante-natal care. However, during and after the birth, particular precautions should be taken to reduce the risk of transmission (see paragraph 4.14). If a home delivery is decided upon, it is the responsibility of the midwife to ensure that any contaminated material is removed and disposed of in line with correct procedures for infected clinical waste.
4.50 Late stage CJD patients may well experience tissue breakdown and the development of extensive pressure point sores. These lesions should be dressed regularly, using standard infection control precautions, and contaminated dressings disposed of as clinical waste by incineration.
4.51 The British Dental Association (BDA) has issued general guidance on the development of practice infection control policies. Individual practice infection control policies, if developed and implemented efficiently, will minimise the risk of transmission of infection. Based on the advice in this document, the BDA are understood to be preparing specific advice for dental procedures on known, suspect or at risk patients.
After Death
4.52 On the death of a known, suspect or at risk patient, the removal of the body from the ward, community setting or hospice, to the mortuary, should be carried out using normal infection control measures. It is recommended that the deceased patient is placed in a body bag prior to transportation to the mortuary, in line with normal procedures for bodies where there is a known infection risk.
Post mortem
4.53 Currently post mortem examinations are essential in order to confirm the clinical diagnosis and the cause of death as CJD or a related disorder. However, such procedures have the potential to expose pathologists and mortuary staff to infectious materials. The following paragraphs give advice on basic precautions for safe working. Further advice is given in the Health Services Advisory Committee publication “Safe working and the prevention of infection in the mortuary and post mortem room”. Specific information on neuropathological autopsy in CDJ cases has been published (see bibliography).
4.54 Only fully trained staff should undertake any necessary post mortem examination on known, suspect or at risk patients. Ideally three people should be present during the examination: The pathologist assisted by one technician, and a further circulator to open or label specimen containers. Observers should be prohibited or kept to a minimum. Post mortem technicians, and others attending out of necessity, should be fully trained in or informed of procedures for such post mortems and made aware of the relevant history of the patient.
4.55 Restricted post mortem examinations on CJD cases can be undertaken in any mortuary. If only an examination of the brain is to be undertaken, the scalp is reflected in the normal way with absorbent wadding underneath the head to soak up CSF and other material when the cranium is opened. The head and neck of the cadaver should then be enclosed in a large polythene bag. The bag serves to contain bone dust while opening the cranium with either an electrical oscillating saw or hand saw. The bag and skull cap can be detached together before sampling the CSF and removing the brain and pituitary.
4.56 If a full scale post mortem examination of a case of CJD is indicated, including removal of the viscera and spinal cord, it is recommended that the body is removed for special handling in a high risk autopsy suite. Arrangements for refund of any removal costs for bodies for CJD autopsies are made through the CJD Surveillance Unit.5 To minimise contamination of the working environment, post mortem examination should be carried out with the body in an open body bag with absorbent wadding. On completion of the autopsy, the body should be sewn up leaving the wadding in situ in the body bag. This has the advantage of absorbing fluids. Any excess wadding should be incinerated. Care should be taken in sewing up the body that ‘burning’ through gloves does not occur by pulling too hard on the twine. The body bag is then sealed. In some circumstances, it may be necessary to remove the body from the bag for autopsy; in these cases the body should be placed into another bag after autopsy, using absorbent wadding as previously, and the original bag should be disposed of by incineration.
4.57 Disposable protective clothing should be worn including theatre suit, gown, apron, hat and double gloves, and a face visor, which completely encloses the operator’s head to protect the eyes, nose and mouth. Consideration should be given to the use of hand protection, such as armoured or cut-resistant gloves.
4.58 Disposable instruments should be used wherever possible, and incinerated after use. If this is not feasible, a set of dedicated instruments for known, suspect or at risk cases is recommended, in order to minimise the frequency of their use and the risk of transmitting infection. Manual or electric saws may be used, although the former do not create aerosols and are easier to decontaminate after use. Instruments and mortuary working surfaces should be decontaminated following the guidance in Annex B.
Anatomy and pathology teaching
4.59 Anatomy Departments are advised not to accept for teaching or research purposes bodies, brain or spinal cord from known, suspect or at risk patients. Departments should make enquiries of those responsible for donating the body, and of the medical staff who were involved in the care of the donor, whether any of the above apply to the donor. Such information will also be useful when formulating their own guidance on exclusion criteria for prospective donors.
Undertakers and Embalmers
4.60 Concern about possible unknown CJD cases does not warrant a level of precaution for undertakers handling intact bodies other than those used generally for all work of this nature. In cases of traumatic injury, it is sensible general practice to minimise contact, particularly in circumstances under which penetrating injuries could arise. Cosmetic work on bodies of patients from a risk group may be undertaken, taking the precautions routinely used when dealing with human cadavers.
4.61 Where the diagnosis of CJD is known or suspected it is advisable to avoid embalming procedures.
Funerals and Cremations
4.62 Relatives of the deceased may wish to view or have some final contact with the body. Such viewing, and possible superficial contact, such as touching the face, need not be discouraged.
4.63 There have been some concerns expressed about whether burial or cremation presents any risks of environmental contamination. Although it is difficult to quantify the risk of environmental contamination associated with burial, due to the range of unknown factors, it is accepted that the risk is likely to be vanishingly small, and there is no need to discourage burial. Similarly, the risk of residual infectivity after cremation is likely to be negligible. There is no need for extra precautions to be taken for either burial or cremation.
4.64 There are no additional precautions needed for transporting the body within the UK. If there is a need to transport the body internationally, it will be necessary to comply with the IATA Restricted Articles Regulations, and any additional requirements of the individual carriers. It should be noted that the IATA Regulations do require embalming of the body.
Exhumations
4.65 A Home Office licence is required before an exhumation can take place. Those involved with such a procedure should follow normal standard practice for exhumations.
5Enquiries should be made to National Creutzfeldt-Jakob Disease Surveillance Unit, Neuropathology Laboratory, Western General Hospital, Crewe Road, Edinburgh EH4 2XU. Telephone 0131 537 1980.
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