Volume 11: Scientists after Southwood
2. The Tyrrell Consultative Committee
The second meeting
Epidemiology
Monitoring of CJD
BSE and medicinal products

2.58 The Tyrrell Committee met for the second time on 11 April 1989 at the NPU in Edinburgh.

2.59 At this meeting the Committee:

• discussed an epidemiology paper prepared by Mr Wilesmith;
• considered a paper on CJD monitoring; and
• considered BSE and medicinal products in more detail.

There was also a presentation by Dr James Hope on the work of the NPU, and the Committee considered the draft research plan prepared by Dr Pickles. ¹

Epidemiology

2.60 At its first meeting the Committee had decided that it needed access to accurate and up-to-date epidemiological data to help it identify relevant areas of research.

Mr Wilesmith's epidemiology paper

2.61 Accordingly, during the Committee's second meeting, Dr Watson introduced an epidemiology paper prepared by Mr Wilesmith. The paper was prepared on 28 March 1989, and:

• provided an updated summary of the number of reported cases and their geographical distribution;
• gave information on general epidemiological features including herd type, within-herd incidence, age- and sex-specific incidence, and breed incidence;
• concluded that a constant incidence of 350-400 per month could be expected until 1993, with a reduction thereafter until the disease died out (assuming that maternal and horizontal transmission did not occur); and
• stated that if maternal transmission did occur, the exact impact on the course of the disease would be impossible to assess, but it would not be enough to sustain BSE in the national cattle population. ²

The Committee's reaction

2.62 Dr Watson expressed some doubts about the conclusion that a plateau had been reached in the number of cases that could be expected each month, because the number of reported cases was still increasing. He suggested that the recycling of bovine material in the feed chain might be affecting the incidence of the disease. ³

2.63 The Committee members were concerned that they had yet to see the raw data on which the current epidemiological assessment had been based. Dr Watson undertook to obtain the information required from Mr Wilesmith. ⁴

Provision of further data

2.64 Two days after the meeting Mr Wilesmith wrote to Dr Tyrrell, offering to provide more details of the results of the epidemiological studies, and proposing that it might be more helpful to meet in person to discuss the data. ⁵ A meeting subsequently took place on 20 April, and the epidemiology of BSE was discussed in detail again at the third meeting on 8 May (see paragraphs 2.74-2.77 below). ⁶

Monitoring of CJD

2.65 The Southwood Working Party had thought it a reasonable assumption that if BSE was transmitted to humans, it would closely resemble CJD. It therefore recommended that monitoring of cases of CJD should take place, and identified 'the surveillance of humans at particular "risk" and formal monitoring of CJD cases, particularly in occupational groups exposed to bovine tissues', as an area of research that should be addressed by the Committee. ⁷

2.66 At its first meeting, the Committee had decided that a paper on the monitoring of CJD would be needed, and that Dr Will should prepare it. ⁸ During the Committee's second meeting Dr Will introduced his paper entitled 'Proposal for the Monitoring of Creutzfeldt-Jakob Disease'. The research proposal's main features were:

• the collection and validation of diagnosis in all death certificates identifying CJD in England and Wales between 1985 and 1989, and in Scotland and Northern Ireland between 1980 and 1989;
• the notification of all newly certified cases of CJD by the Office of Population Censuses and Surveys (OPCS) or its equivalent in Scotland and Northern Ireland;
• all neurologists, neuropathologists and neurophysiologists would be asked to report all suspect CJD cases, and epidemiological information would be obtained by standard questionnaire; and
• because of the potentially long incubation time, monitoring of CJD would be necessary for at least a decade. ⁹

The Committee's views on the proposals

2.67 The Committee noted that the Southwood Report's assumption - that if BSE was passed on to humans it would be like typical CJD - might not be the case. The important questions in monitoring CJD were the accuracy of the diagnoses made and how they could be confirmed. A monitoring system would have to be maintained for longer than 10 to 20 years, ¹⁰ which meant that it had to be simple to run and not require changing while in progress. ¹¹

2.68 The Committee approved the proposals in Dr Will's paper. ¹² Volume. 8: Variant CJD should be consulted for further discussion of CJD monitoring.

BSE and medicinal products

2.69 The Southwood Working Party had noted that there was a remote risk that 'medicinal products for injection or surgical implantation which are prepared from bovine tissues, or which utilise bovine serum albumin or similar agents in their manufacture' could transmit BSE to humans. The Working Party recommended that the attention of the Licensing Authority, the Committee on Safety of Medicines (CSM), the Committee on Dental and Surgical Materials and the Veterinary Products Committee be drawn to BSE so they could take appropriate action. ¹³

2.70 At its second meeting the Tyrrell Committee was presented with a paper that outlined research questions of immediate interest to the DH Medicines Division and the pharmaceutical industry:

- can freedom from BSE-contamination be demonstrated in existing stocks of products at theoretical risk (many years supply of some vaccines, for example)?

- for what processes/products are the risks sufficiently high to be worth subjecting to experimental test, eg with mouse inoculation?

- how can BSE-free herds in the UK be demonstrated and material collected from these herds?

- what overseas sources of bovine material are acceptable?

- are there any products for which the risk-benefit is now unacceptable [considered for the bovine insulins and heparin, but further action not thought appropriate at present]?

- should there be similar concern about other animal species used in pharmaceutical manufacture? ¹⁴

2.71 Other papers outlining potential problems and action taken to date were appended, including:

• a list of medicinal products for human use that contained bovine ingredients or used bovine ingredients in their preparation;
• a position statement by the CSM, saying that the risk to humans of infection via medicinal products was remote, but that guidelines on good manufacturing practice had been produced as a safety measure;
• a copy of the guidelines and letter sent to all manufacturers of human and veterinary medicines; and
• a question and answer briefing prepared by DH in response to the Southwood Report, indicating the line taken up to then.

The Committee's response

2.72 Dr Tyrrell explained that the papers were mainly for the information of the Committee, but still raised questions relevant to research needs. Further, although the CSM's position statement correctly claimed that the risks from BSE were small, there was still a need to conduct research. ¹⁵ Dr Kimberlin told the Inquiry that although the words 'remote' and 'theoretical' were used, they were not taken to mean that no work needed to be done in this area. ¹⁶

2.73 Dr Will pointed out to the Committee that the papers did not cover dental products, which might be of concern given that transmission of kuru could have involved gum abrasions. ¹⁷