ACMSF Meeting minutes 19 September 2000

Minutes of the 38th ACMSF Meeting, 19 September 2000, Department of Health, London.

Present

Chairman Professor D L Georgala

Members Mr D Clarke
Dr T Clayton
Mrs P Jefford
Professor A M Johnston
Ms E Lewis
Dr M J Painter
Dr T A Roberts
Dr N A Simmons
Dr J V Stevens
Mrs B W Thomas
Dr T D Wyatt

Assessors Dr M Donaghy (SEHD)
Mr P J R Gayford (MAFF)
Professor C H McMurray (NIDARD)
Dr R Skinner (FSA)

Secretariat Dr J Hilton (Medical Secretary)
Mr C R Mylchreest (Administrative Secretary)
Mrs E A Stretton

Others Ms G Hoad (FSA) - for item 5
Dr I Grant (Queen's University, Belfast) - for item 5
Dr P E Cook (FSA) - for item 6
Mr A Kyriakides (J Sainsbury) - for item 7

1. Chairman's introduction

1.1 The Chairman welcomed Members to the Committee's thirty-eighth meeting.

1.2 Professor Georgala reminded Members of the need to declare any interests in any of the items for discussion, and himself made a personal statement in relation to agenda item 5 (see paragraph 5.1). Dr Stevens also clarified his position in relation to the same agenda item.

1.3 No other declarations of interest were made.

2. Apologies for absence

2.1 Apologies were received from three Members (Mr Kilsby, Professor Palmer and Professor Smith) and one Assessor (Dr Mitchell).

3. Minutes of the thirty-seventh meeting (ACM/MIN/37)

3.1 These had been circulated to Members shortly after the 37th meeting, and suggested amendments had been incorporated into the revised draft.1

3.2 The amended minutes were approved as a correct record of the 37th meeting.

4. Matters arising

4.1 The Chairman confirmed that there were no substantive issues arising from ACM/MIN/37 which were not covered by the agenda for the 38th meeting. However, action had been taken on a number of matters and he asked the Secretariat to append a progress report to the minutes of the 38th meeting, for record purposes. This is at Annex A.

5. Research and surveillance update

5.1 Professor Georgala made a statement about a personal conflict of interest in relation to this agenda item. He recalled that, when the subject of Mycobacterium avium subsp. paratuberculosis (MAP)2 had first been addressed as a major item by the Committee, at its 30th meeting, he had declared a personal interest arising from his position as a consultant to Express Dairies, a major dairy group. As this discussion pre-dated the adoption of the Code of Practice for Members of the ACMSF (see ACMSF Annual Report 1999, Annex IV), Professor Georgala recalled that he had taken a personal decision to withdraw from the room while the item had been discussed. His action reflected the fact that the item was of great potential importance to the whole dairy industry and that there were many scientific uncertainties associated with it. In the circumstances, Professor Georgala had considered that he should withdraw from the 30th meeting whilst the MAP item was discussed, to avoid any possible misunderstanding of his position.

5.2 Professor Georgala confirmed that he remained a consultant to Express Dairies. Having discussed the matter with the Secretariat, he had decided on this occasion to ask Professor Johnston to take over the Chair for this item of the agenda. Professor Johnston would determine with Members whether Professor Georgala should participate in the discussion or withdraw from the meeting whilst the item was dealt with.

5.3 Professor Johnston assumed the chairmanship. He reminded Members of the provisions of the Code of Practice governing their membership as they impacted on this question. The Code provided that :-

"Members of the Committee are required to declare any direct commercial interests'..in matters under discussion at each meeting. Having fully explained the nature of their interests, the Chair may, having consulted the other members present, decide whether and to what extent the member should participate in the discussion and determination of the issue. If it is decided that the member should leave the meeting, the Chair may first allow them to make a statement on the item under discussion."

5.4 Ms Lewis and Dr Simmons both expressed the view that Professor Georgala should remain and should participate in the meeting, given his personal statement and the value of his expertise to the Committee. There was no dissenting voice and it was so decided.

5.5 Dr Stevens took the opportunity of clarifying his position. He recalled that he too had declared an interest when the matter had been debated at the Committee's 30th meeting. Unigate plc, the company of which he was Technical Director, had at that time, been actively engaged in the sale of liquid milk, cheese and other dairy products. In the circumstance, Dr Stevens had withdrawn from the meeting along with Professor Georgala. He was now Group Technical Director of Unigate Convenience Foods and the company had divested itself of its liquid milk business. He thus considered that he no longer had a strong personal interest in the subject.

5.6 Turning to the substance of the agenda item, Professor Johnston directed Members¿ attention to the 3 papers provided. ACM/485, presented by Ms Geraldine Hoad (Food Standards Agency (FSA)), contained MAP results from the FSA national study on the microbiological quality and heat processing of cows¿ milk. Results of MAP culture were presented for 679 samples (81.8% of those tested). These showed that viable MAP was found in 1.9% of raw milk samples and in 2.1% of pasteurised milk samples. The 10 samples of pasteurised milk found to contain the organism came from 8 different dairies situated throughout the UK, and ranging in size from small to very large. A variety of pasteurisation times and temperatures (including extended times up to 25 seconds) had been used. No evidence could be found suggestive of inadequate pasteurisation or cross-contamination at dairies. Molecular typing of the strains showed that cross-contamination with laboratory strains could not account for the results.

5.7 Ms Hoad reported that the results of the other microbiological examinations carried out under the survey would be presented to the Committee at a later date.

5.8 Among the points made by Members during discussion of technical issues arising from ACM/485 were that :

- given that a 150ml sub-sample had been aseptically drawn by laboratories from the samples taken, for onward transmission to QUB for MAP testing, the possibility of cross-contamination at that stage could not be completely ruled out in the absence of a detailed audit of the procedures followed; and

- although UHT milk had been regarded by FSA as unlikely to prove problematical in terms of MAP (reflected in the small number of samples taken), this could prove to be an unfounded assumption in certain circumstances (eg. in the case of cross-contamination after heat treatment).

5.9 ACM/486, presented by Dr Irene Grant (Queen's University, Belfast (QUB)), summarised the results of FSA (and previously MAFF)-funded laboratory research on the heat resistance of MAP in milk at pasteurisation temperatures. The work showed that MAP at concentrations above 100 CFU/ml was able to survive high temperature short time pasteurisation, probably due to clumping of cells in naturally-infected raw milk. The laboratory studies suggested that longer pasteurisation times (particularly 25 seconds) were associated with inactivation of high inocula of MAP. Increased temperatures did not have this effect.

5.10 Technical points raised in relation to paper ACM/486 included :

- QUB began culturing for surviving cells immediately post-pasteurisation. It was possible that, had testing of samples been delayed until 24-48 hours after pasteurisation, this would have influenced the recovery of heat-injured MAP cells;

- it was clear that clumping offered a measure of protection to cells in the middle of the clumps. However, it was not clear whether disrupting clumps affected the tailing exhibited in the thermal inactivation curve of MAP;

- clumping appeared to be a much more significant phenomenon in MAP than in other mycobateria;

- the proposition that MAP could survive HTST pasteurisation at 90¿C was difficult to reconcile with current understanding of the effect of increasing temperature on the death of microorganisms;

- Dr Stevens mentioned that dairy industry data (which he said could be made available as a paper to the Committee, if required) were available from 462 samples of milk pasteurised at 72¿C for 25 seconds tested at QUB showing no MAP surviving. In the absence of more detailed information, such as that provided in ACM/485, the Committee was unable to evaluate the significance of these reported results.

5.11 ACM/487, presented by Dr Hilton, reviewed the information in papers ACM/485 and 486, together with recent expert opinion on the role of MAP in human Crohn's disease (including reports from the Food Safety Authority of Ireland (ACM/493), and the EU Scientific Committee on Animal Health and Animal Welfare). The Committee's advice was sought on any implications for the food chain. Specifically, Members were asked :

- whether the results now available confirmed to their satisfaction the ability of MAP to survive pasteurisation, including pasteurisation at time/temperature combinations that went beyond the legal minimum (72°C for 15 seconds);

- to advise on the implications of the findings for the food chain and, in particular, to consider whether existing advice on the consumption of milk remained appropriate; and

- to advise on any further work they considered should be put in hand to provide a sounder basis for assessing and managing the risks.

5.12 In response to a request for information on MAFF-funded work in connection with Johne's disease3 in dairy cattle, Mr Gayford reported that the Scottish Agriculture College were currently conducting a review. The aim was to report in two parts, the first at the end of September 2000 and the second by mid-November 2000. The reports would then be put to interested organisations for comments, with a final report being made available by early 2001. The mid-November report could be put to the ACMSF on 5 December, although MAFF would not by then have had sufficient time to assess it in detail.

5.13 In the ensuing detailed discussion of the evidence presented to, and the questions directed at, the Committee, the following points were made by Members :

- although it was not clear one way or the other whether MAP caused Crohn's disease in humans, the balance of medical and scientific opinion appeared to be that the possibility could not be ruled out completely. The evidence was equivocal;

- MAP was occasionally present in milk going into retail distribution in the UK. It was not absolutely clear that its presence was because it survived pasteurisation. It might, for example, reflect cross-contamination in the dairy;

- laboratory heating experiments could not reproduce commercial pasteurisation conditions. The volumes of milk tested were small, compared with total volumes. Much larger volumes could be tested by concentrating (eg filtration) and this would also avoid sub-sampling;

- whilst current data suggested that MAP could survive pasteurisation for 25 seconds, further increases in pasteurisation times could affect the organoleptic qualities of the milk;

- a group was needed to consider MAP at all stages from primary production to dairy processing, to list the options for reducing exposure by preventing it getting into milk or minimising the level of contamination, and to assess their potential effectiveness. Proper account needed to be taken of consumer concerns, including the risk of exposure in children;

- in the Secretariat's view, in the absence of any new information about a possible link between MAP and Crohn's disease, it was unlikely that the Advisory Committee on Dangerous Pathogens would be able to add anything new to the debate;

- in relation to the mechanism for reviewing the CMO's current advice that there was no need for consumers to alter their dietary habits, this was not something which needed concern the Committee directly. ACMSF advice should go to the FSA. If the Agency then felt that some change was needed in the CMO's advice, it would make the necessary representations to the CMO.

5.14 In conclusion, the Committee agreed that the interim results from the FSA's national milk survey showed that viable MAP was present in a small number of samples of commercial pasteurised milk for retail sale. Members felt that research studying the death rate of MAP under laboratory conditions tended to support the results of the national survey.

5.15 The Committee noted the current balance of scientific opinion that the link between MAP and Crohn's disease had neither been proved nor disproved. On the basis that the risk to human health had not yet been established, the Committee did not recommend any change in the current advice regarding the consumption of milk.

5.16 However, given the different views on possible links to human illness, which were not likely to be resolved in the foreseeable future, the Committee recommended that the Agency should convene a group of stakeholders, with an appropriate level of seniority and practical experience, to consider all aspects of the control of this organism, including longer term options for control in primary production and developments in dairy technology, taking due account of consumer concerns, such as the risk of exposure in children.

6. Salmonella in Eggs Report

6.1 Dr Painter (Chairman of the Working Group on Salmonella in Eggs) introduced the Group's draft report (ACM/488), together with a risk assessment supplement (ACM/489).

6.2 Dr Painter reminded Members that they had seen a partial draft at the Committee's 37th meeting in June. Their comments from that meeting had been reflected in the current drafts. He hoped that the full draft report now read better and progressed more logically. Dr Painter continued with a brief overview of the structure of the report, highlighting areas which had given the Working Group particular difficulties, particularly in obtaining information required. At the same time, emerging indications of real progress in tackling the Salmonella in eggs problem were very encouraging, as was the fall in human cases of Salmonella infection which might support these indications. Dr Painter also gave a brief resume of the risk assessment report which, in view of its size, the Working Group had decided should be produced as a separate free-standing supplement to the report itself.

6.3 As regards the next steps, and assuming the Committee was largely content with the drafts, the intention was that they should go back to the Working Group to enable final tidying up to be carried out, including reflecting any points made by Members at the current meeting.

6.4 Professor Georgala reminded Members that the report would go forward to the FSA as a report of the whole Committee, not just of the Salmonella in Eggs Working Group. It was therefore important that Members took full collective responsibility for what went forward in the Committee's name.

6.5 The Committee endorsed the main thrust of the report and the risk assessment supplement. Members congratulated Dr Painter on his and the Working Group's considerable efforts and the quality of their output. Dr Painter in turn expressed particular appreciation of Mr Mylchreest's contribution. The Committee was content with both drafts, subject to a number of detailed drafting suggestions. Dr Painter undertook to reflect these in the final tidying up process, prior to putting final versions back to the Chairman for submission to the FSA.

7. In-shell egg pasteurisation

7.1 Following the announcement by J Sainsbury plc that it had produced the UK's first in-shell pasteurised eggs, the FSA had sought the ACMSF's views on the effectiveness of the process from a microbiological food safety standpoint. To help inform the Committee's deliberations, Sainsbury's Chief Microbiologist, Mr Alec Kyriakides, presented paper ACM/490 which gave information about their in-shell pasteurisation process.

7.2 Mr Kyriakides said that Sainsbury's aim was to offer consumers an egg pasteurised in-shell which could safely be consumed in raw egg dishes. The raw material would be Lion quality eggs pasteurised within 3 days. The process involved simple heating in humidified air in an oven. The egg was heated all the way through. The challenge was to be able to control the time and temperature with the precision needed to achieve the required lethality without adversely affecting the egg. The process had been tested using a cocktail of salmonellas. The minimum process lethality achieved had been better than a 4 decimal (4D) reduction. The probability of one contaminated egg reaching the market was assessed as about 1 in 10 million eggs. The in-shell pasteurised eggs had performed well in a range of dishes. The company was consulting MAFF on where the product stood in relation to EU egg marketing regulations. Studies were in train to consider the microbial stability of the in-shell pasteurised eggs compared with standard eggs. Challenge testing was under way for a range of pathogens not normally associated with eggs (eg. Listeria monocytogenes, Bacillus cereus and Clostridium botulinum), as well as for Salmonella enteritidis, to determine growth potential during ambient storage. If these studies were to indicate any loss of stability, then the eggs would be stored under refrigeration with a clear instruction to keep refrigerated.

7.3 Among the detailed points arising in discussion were that :

- in the absence of refrigerated storage, microbial growth appeared to be initiated earlier in in-shell pasteurised eggs than in standard eggs;

- a 6 decimal (6D) reduction (at least) could be expected on the outside of the shell;

- inocula had been made up with yolk or albumen before being injected into the egg.

7.4 In subsequent discussion the Committee concluded that the achievement of a 4D reduction would make a positive contribution to the microbiological safety of eggs. However, the Committee had not been presented with complete processing data and the claimed effects of the process would need to be validated.

7.5 Members expressed some disquiet at being asked to give advice about a specific product produced by a single company. The Committee had no role in product approval or licensing and its advice had traditionally been confined to generic issues.

8. Mycobacterium bovis

8.1 Members considered paper ACM/491 containing information on the current incidence of and trends in M. bovis infection in cattle and humans, and on the measures in place to protect the food chain from risks associated with the organism. The information contained in ACM/491 superseded similar information provided in ACM/480, consideration of which had been deferred from the 37th meeting. The milk and dairy products exposure pathway seemed well protected by existing legislation and control measures. Questions remained about the meat exposure pathway and the level of protection offered by current legislation and practice. The paper proposed the establishment of an ACMSF Working Group to review the possible health risks associated with the consumption of meat from animals with evidence of M. bovis infection and to provide advice to the FSA.

8.2 The Committee regarded it as reassuring that the marked rise in tuberculosis in cattle had not been reflected in the trend of human cases of TB due to M. bovis. These remained very small (on average only 42 cases a year out of approximately 3,600 bacteriologically-proven cases of TB). The Committee nevertheless regarded the increase in bovine TB as of concern and agreed to the setting up of the proposed Working Group. The Secretariat was asked to progress the questions of terms of reference, membership and timetable in consultation with the Chairman.

9. ACMSF open meeting

9.1 The Chairman introduced paper ACM/492 containing proposals for the conduct of the Committee's first open meeting to be held on 5 December 2000. The aim would be for the meeting to proceed on as normal and as orderly a basis as possible. This would require a disciplined approach by Members in terms of attendance, punctuality and interventions, and during the public question and answer session, if the twin objectives were to be achieved of completing ACMSF business efficiently and ensuring that members of the public derived maximum benefit from attendance.

9.2 Members were content for detailed planning to continue on the basis of the broad principles outlined in ACM/492.

10. Any other business

10.1 Two matters were raised under Any Other Business.

10.2 First, Dr Donaghy gave an oral report on progress in connection with the setting up of a joint FSA/Scottish Executive Health Department Task Force on E. coli O157. The Task Force's remit would be to review, in the light of information on the incidence of E. coli O157 in Scotland, the risk to public health and current activities to prevent human infection with E. coli O157; to assess the effectiveness of existing arrangements for coordinating action at the local and national levels; and to consider options for protecting public health. The results of recent research and a case control study suggested that O157 infection was now more often associated with direct exposure to animals and environmental sources contaminated with animal faeces than food.

10.3 The Task Force, which was due to report by the end of May 2001, would be chaired by Professor Bill Reilly of the Scottish Centre for Infection and Environmental Health. Membership would comprise 8 specialists representing microbiology, public (ie medical) and environmental health, veterinary medicine, farming, water supply and consumers. There would be 2 representatives from sponsoring Departments, Dr Donaghy himself and a representative from FSA/Scotland. The Task Force would include one member from England.

10.4 Dr Donaghy said that the intention was to open up the debate and that all those with an interest would be encouraged to take advantage of the opportunity for contact with the Task Force. After an initial exploratory meeting on 27 September, work would focus on a number of specific study areas including animal contact, agriculture, water supply, other rural land usage, and food. Risk assessment, risk communication and consumer issues would also be addressed.

10.5 Dr Donaghy said that the Task Force was keen for its findings to be of use on a UK-wide basis. It was important to engage the relevant UK scientific advisory committees and interested parties outside of Scotland. The role of the ACMSF as the FSA's principal source of independent advice on microbiological food safety was fully recognised. There were a number of non-mutually exclusive options for involving the ACMSF in the Task Force's work including:

- co-option of an ACMSF member onto the Task Force;

- the Task Force holding an "ACMSF day" in Scotland;

- Professor Reilly visiting London to present to the ACMSF at the draft stage the Task Force's findings, and incorporating the Committee's views into the Task Force's report;

- formally consulting (ie. in writing) the ACMSF on the Task Force¿s report.

10.6 In response, Professor Georgala welcomed the proposed UK approach and the intention to involve the ACMSF. He undertook to consult further as necessary on the detail of ACMSF involvement.

10.7 The second matter, raised by Mr Gayford, concerned the outbreak of Classical Swine Fever, principally in East Anglia. Mr Gayford said that swine fever was not zoonotic, and would not normally be a matter for the ACMSF. However, the Committee ought to be aware of the way in which the outbreak was progressing, given the major impact which the development and implementation of counter-measures were having on MAFF and State Veterinary Service (SVS) resources. The outbreak had arisen in August, when 5 herds had been involved. Infected herds had been slaughtered out and movement restrictions had been introduced. To date, infection had been confirmed in 13 herds in 2 breeding chains. The heavy demand on resources was likely to last until Christmas and would affect the way MAFF and the SVS were able to respond to competing priorities.

11. Future meetings

11.1 As noted under agenda item 9, the final meeting for 2000 would take place on 5 December and would be held in public.

11.2 The following dates were agreed for meetings in 2001 :-
21 March
27 June
19 September
5 December

Annex A

ANNEX A PROGRESS REPORT ON MATTERS ARISING FROM THE COMMITTEES 37TH MEETING

ACM/MIN/37 paragraph Action requested Latest position

3.1

Amendment to ACM/MIN/36, para. 5.5

Amended minutes have been placed on FSA website as ACM/MINS/36 (Final)

6.5

PHLS to be invited to report again to ACMSF on microbiological status of RTE fruit and vegetables early in 2001

Secretariat wrote to PHLS on 7 July 2000.

7.2

Members' comments on Salmonella in Eggs Working Group's draft report to be reflected in subsequent draft.

Agenda item 6.

8.6

FSA to consult IFR and CCFRA and prepare a paper for ACMSF on C. botulinum.

Secretariat wrote to FSA on 7 July 2000.

9.3

Informing Members of outcome of May review of risk assessment

Secretariat sent copies of final May Report to Members on 10 August 2000.

10.1

Set up Surveillance Working Group

ACM/496 reporting latest position amongst information papers for 38th meeting.

12.1

Papers on Listeria outbreaks (ACM/477) and M. bovis (ACM/480) to be carried over to later meeting.

It is probable that the Listeria item will be discussed in December.

Earlier M. bovis paper (ACM/480) subsumed into ACM/491, for discussion under item 8 of 19 September agenda.

13.1

ACMSF to comment in relation to review of veterinary surveillance in E&W

Secretariat sent ACMSF comments on 29 June 2000.

14.1

Informing Members about open meeting

Secretariat wrote to Members on 4 July confirming that December (rather than September) was likely to be the open meeting.