ACMSF Minutes: 22 September 2011

Meeting held at 1pm in Aviation House, 125 Kingsway, London WC2B 6NH.

Present

Chair: Prof S O’Brien

Members:
Dr B Adak
Mrs V Buller
Prof J Coia
Mrs R Glazebrook
Prof J Gray
Dr R Holliman
Ms J Hopwood
Prof D McDowell
Mr P McMullin
Dr S Millership
Mr D Nuttall

Assessors:
Ms L Redmond (FSA)
Mr S Wyllie (Defra)

Secretariat:
Ms G Hoad (Administrative Secretary)
Dr P Cook (Scientific Secretary)
Mr A Adeoye
Ms S Butler
Dr S Rollinson

Presenters:
Dr C Tam (London School of Hygiene & Tropical Medicine)
Dr D Tompkins (WRAP)

Others:
Ms Fiona Brookes, Northern Foods
Ms Andrea Carruthers, 3M Health Care Ltd
Ms Catherine Cockcroft , Exova
Ms Georgina Crayford, Agriculture and Horticulture Development Board
Ms Kaarin Goodburn, Chilled Food Association
Mr Alan Lyne, ADAS
Mr David McCleery, Safefood
Mr Tom Miller, Retired Consultant
Mr Barry Mirhabib, Brakes
Mr Alan Procter
Dr Helen Rees, ADAS
Mr Mark Rees, 3M Health Care Ltd
Mr Ian Sheldrake, Matrix MicroScience Ltd
Ms Karen Sims, Waitrose
Mr John Tayleur, Defra
Ms Kara Thomas, British Retail Consortium
Ms Nicola Wilson, Westward Laboratories
Mr Michael Wood, Norpath Scientific Services

1. Chair’s introduction

1.1 The Chair welcomed ACMSF Members and members of the public, to the Committee’s 76th meeting. She also welcomed Dr Clarence Tam from the London School of Hygiene and Tropical Medicine who would be co-presenting item 6 and Dr David Tompkins from the Waste and Resources Action Programme (WRAP) who would be giving a presentation under agenda item 8.

2. Apologies for absence

2.1 Apologies for absence were received from Mr J Bassett, Dr R Betts, Mrs J Morris and Prof P Williams.

3. Declarations of interest

3.1 The Chair reminded Members of the need to declare any conflicts of interest relating to items on the agenda, both at the beginning of the meeting and subsequently if the need arose during discussions. Prof O’Brien declared an interest under item 6 as she was the lead contractor for the Second Infectious Intestinal Disease Study. Prof Coia declared that he provided occasional consultancy advice for Tesco. Mr McMullin declared an interest as a poultry veterinarian in relation to vaccine discussions under agenda item 7.

4. Minutes of the 75th meeting (ACM/MIN/75)

4.1 As there were no comments on the minutes they were accepted as an accurate record of the last meeting and the Secretariat was asked to publish them on the ACMSF website.
Action: Secretariat

5. Matters arising (ACM/1032)

5.1 Ms Geraldine Hoad drew Members’ attention to the summary of action taken on matters arising from previous meetings. All actions had been completed except for those in relation to horizon scanning and raw milk where work was still in progress.

6. Chief Scientist

6.1 The Chair welcomed Dr Andrew Wadge, FSA Chief Scientist, who joined the meeting at this point and invited him to say a few words. Dr Wadge expressed the Agency’s appreciation for the work carried out by the Committee. He said that the Chair, Jeff Rooker, the Chief Executive, Tim Smith, the Board Members and Directors were all committed to having a strong evidence base for the Agency’s work. The advice from ACMSF, whose work was closely linked to the Agency’s strategic aim of reducing foodborne disease, was greatly valued.

7. Infectious Intestinal Disease Study 2 (ACM/1033)

7.1 Dr Rick Holliman chaired this item and introduced paper ACM/1033 noting that the Committee had received a progress report on the second Infectious Intestinal Disease Study (IID2) in June 2006. The findings of the study had been published earlier in the month and Prof O’Brien and Dr C Tam were invited to give a presentation on the work.

7.2 Prof O’Brien explained that the main driver for the study was to establish whether the incidence of IID in the community had changed since the mid 1990’s (when IID1 was undertaken) and to help establish a baseline against which to measure any reduction in foodborne disease. Two methods were employed in the study to describe IID in the community; a retrospective telephone survey of self-reported illness and a prospective cohort study. A selection of molecular, immunoassay and culture-based methods were also used to detect the presence of micro-organisms in samples submitted.

7.3 Dr Tam presented the rates of IID calculated in the study based on the telephone survey and the cohort study. It was calculated that for every case of IID reported to national surveillance there were about 10 GP presentations and 147 community cases. Overall there were an estimated 17 million cases of IID per year in the UK. The rate of overall IID in the community in England had increased from IID1 to IID2 by about 50% but the rate presenting to primary care had halved, suggesting the way in which people use GP services has changed over the time between the two studies. The reporting patterns for specific pathogens were presented and it was highlighted that the incidence of Campylobacter and norovirus had increased since IID1 (to 500,000 and 3 million respectively) but cases of Salmonella infection had decreased dramatically. Norovirus was the most commonly recognised cause of IID. It was estimated that 18.8 million school/working days were lost due to IID in the UK per year. The study limitations and strengths were briefly highlighted as was further work to determine the food-related component of IID.

7.4 The Chair thanked Prof O’Brien and Dr Tam for their comprehensive presentation of the study and invited questions from Members. The following points were raised:

  • The study showed that IID rates in the community had increased since the mid-90’s but that presentation to GPs with IID had decreased. The possible reasons for this observation were discussed. It was suggested that fewer people are presenting to their GPs but of those that do more samples are being taken, also patients with diarrhoea and vomiting are asked not to attend GP surgeries in winter to prevent spread of disease. Information was not sought from study participants on the process of getting an appointment and it was hypothesised that delays in getting an appointment may change presentation patterns, as with shorter-term illnesses patients may recover before they can get an appointment. The study did try and mitigate for this possibility as the molecular methods used had the ability to detect pathogens in older samples. It was noted that previous studies have shown that severity and length of illness (i.e. over 5 days) are the factors that drive people to seek GP consultation.
  • The number of people in the telephone survey calling on behalf of children was queried. Dr Tam explained there was a limited amount of information that could be extracted from the phone data but they recognised a large number of the calls represented the 0-5 years age group.
  • There was some discussion on comparison of molecular versus conventional diagnostics within the study and it was noted that Salmonella case numbers were higher if results from molecular methods were incorporated.
  • There was a suggestion that direct linkage with medical records may have been helpful in calculating reporting ratios from the community to national surveillance. Prof O’Brien noted that it was a pragmatic decision to use an indirect method in the study to calculate the rates of IID presenting as it would have been very difficult to contact every Health Protection Unit (HPU) to obtain relevant data.
  • Information on non-respondents in the cohort study was requested. It was noted that only limited data could be collected on the non-respondents so formal comparisons were difficult. Looking at the composition of those that did participate there were more female respondents, fewer young adults and more respondents in a rural setting and with a managerial role.
  • The presenters were asked to comment on the implications of the study on the Agency’s foodborne disease strategy. Prof O’Brien noted that although research to assess the foodborne component had not yet been completed, it was possible to say that of the two most significant IID pathogens the majority of Campylobacter was likely to be foodborne and therefore the FSAs focus on this was appropriate. However, in terms of norovirus it was more difficult to say what proportion was foodborne, estimates in the literature varied from 11-40% which still suggested action to tackle foodborne norovirus was required.

7.5 In summarising the Chair noted that the Committee had made comments on how changes in access to GPs may affect comparative surveillance, on further investigations for those phoning on behalf of illness in others and on the consistency and comparability of pathogen detection methods. They also suggested that a breakdown of age distribution by pathogen, rather than by totality of disease may be useful. The Committee noted that more focus was needed on the proportion of food related IID and the impact this may have.

8. Risk profile in relation to Toxoplasma in the food chain (ACM/1034)

8.1 Dr Holliman presented the final report of the Ad Hoc Group on Vulnerable Groups on Toxoplasma in the food chain, thanking the co-opted members of the group (Dr Ed Guy and Mr Paul Hutchinson), Miss Jodie Crab and Dr Judith Hilton for their contributions to the report. The contents of the report chapters were outlined. These covered the stages of human infection and parasite lifecycle, clinical disease, prevalence and burden of human disease, sources of infection (focussing on food animals), survival of Toxoplasma in foodstuffs and evidence on the importance of foodborne infection versus environmental infection (one of the key considerations of the report). Consumer advice on toxoplasmosis given in the UK and in different countries was also outlined in the report. The main data gaps, conclusions and recommendations of the report were brought together in the final chapter.

8.2 Dr Holliman noted that a small proportion of people acquire toxoplasmosis but these suffer the greatest ill health. One of the report recommendations was therefore for further work to look at the burden of disease and the prevalence of toxoplasmosis, possibly through a seroprevalence study to provide information on the effectiveness of current controls and allow for more robust risk management strategies. A case-control study was also recommended to provide further information on how much infection may be due to contaminated food and how much due to other sources. It was also acknowledged that there was little data on the effect of food preparation processes on Toxoplasma. The report noted there was considerable variation in the toxoplasmosis related advice given by different countries. A recommendation was therefore made to review UK advice to pregnant women and update this in light of current information giving consideration to including other immuncompromised groups. Views and comments on the report were sought from the Committee.

8.3 The Committee made the following comments in discussion:

  • The report makes no reference to human vaccination and there is little discussion on animal vaccination and whether this could reduce the burden of disease in animals. It was noted that there is no human toxoplasmosis vaccine available and vaccination against Toxoplasma in animals is primarily intended to protect animals from risks during the breeding season rather than decrease the Toxoplasma load in the foodchain. It was suggested that a vaccine which targets the intestinal lifecycle of the parasite (as with coccidial vaccines) could reduce levels of Toxoplasma in livestock and thereby the levels entering the foodchain.
  • The feasibility of a case control study on toxoplasmosis was questioned given the regional differences in seroprevalence and the variation in the relative importance of food sources estimated in different countries. It was noted there would be significant challenges associated with sample size and hypothesis generation for such a study. Dr Holliman accepted that there were difficulties with a case-control study but a robust measure of the foodborne component of toxoplasmosis was key in assessing the human health risks and accurately estimating the burden of disease which was probably under-recognised at present.

8.4 The Chair summarised that it would be useful to include a brief comment on the absence of a human vaccine and the use of animal vaccines in the report. The data in paragraph 6.6 should be presented in a tabular form and table 5 should be amended so a clearer comparison of advice given by different countries could be made. Subject to these amendments the Committee agreed the report should be published for public consultation.

Action: Secretariat

9. Waste and Resources Action Programme (WRAP): Quality, safety and use of digestate in UK agriculture (ACM/1035)

9.1 The Chair introduced paper ACM/1035 explaining that the relevant chapters of WRAP’s report on digestates had been circulated for Members use only and that the Committees views on microbiological food safety aspects of the report were sought. Dr David Tompkins from WRAP was invited to brief the Committee on the report on the quality, safety and use of digestates in UK agriculture.

9.2 Dr Tompkins explained the main drivers for production of the report in terms of the reduction and re-use of food and drink wastes. The different types of digestate, the remit of WRAP and the scope of the report were also outlined. The report brings together seven discreet pieces of work commissioned through WRAP each presented in a separate chapter. The Committees views were primarily sought on the robustness of the anaerobic digestates risk assessment and the Clostridium botulinum review. The risk assessment was intended to deliver a matrix for digestate (Biofertiliser) use and give clear risk-based guidance to minimise food safety risks. Views were also sought on whether the proposed matrix gave adequate safety for the ranges considered. Dr Tompkins highlighted that multiple feedback streams for the report were in place and it would be amended to take comments into account as it was important that both digestate producers and users had confidence in the report. The aim was to publish the report in full in 2012.

9.3 The Chair noted that a number of specific questions were outlined for consideration by the Committee in reviewing the report and requested comments from the Committee in relation to these.

9.4 In discussion the Committee made the following comments on the report:

  • Consideration should be given to the inclusion of non-O157 VTEC in the risk assessment.
  • More consideration on the effect of anaerobic digestion on TSEs was needed.
  • In terms of the proposed biofertiliser matrix, given the crucial role of pasteurisation, the use of pasteurised digestate only on Category 3 fresh produce should be considered if the produce would be eaten lightly cooked or uncooked.
  • Many data gaps were highlighted in the report in relation to C. botulinum which had prevented any conclusions being drawn on the associated risks in digestates. The ACMSF had, in the past, considered botulism in cattle, where many data gaps also existed; they had, however been able to reach a reasonable assessment of risk. Recent research concerning growth of clostridia in culture media may provide a useful alternative to animal models and could be explored to address some of the data gaps. It was suggested that C. botulinum in poultry litter could potentially be used as a worst case scenario to help plug some of the data gaps.
  • It was suggested that the persistence of organisms is the important factor to consider in assessing the risks from digestates, particularly in relation to C. botulinum. In many instances the report states that no significant growth of organisms was found and the tone of document therefore implies that, if there is no significant growth of organisms, the situation won’t be getting any worse. However, there is no evidence to support this assumption.
  • Mr Wyllie noted that, in relation to scrapie, food chain production systems would reduce exposure as only low risk animal by-products are allowed into the system. Therefore there should be a very low risk in the case of waste from the food chain with respect to scrapie.
  • Dr Tompkins responded that, with respect to TSEs, it was difficult to assess the risks as there was little information on secondary exposure to TSEs. He also clarified that in relation to C. botulinum two further pieces of work were progressing; one to look at the impacts of un-pasteurised versus pasteurised digestates on a range of diseases including C. botulinum and another to gather field evidence on C. botulinum spore loadings in the environment. In relation to Category 3 fresh produce Dr Tompkins highlighted that the Red Tractor protocols were being re-issued and would not permit unpasteurised anaerobic digestates on Category 1, 2 or 3 produce.

9.5 Members noted that there was a lot of information to consider in the report and it would be helpful to be able to look at this in detail. The Chair therefore agreed that the group of Members that considered the previous WRAP report should be re-convened to give more detailed scrutiny to the anaerobic digestates report. A couple of additional Members would be needed to replace those that had retired since the group last met.
Action: Secretariat

10. Mycobacterium bovis and the possible health risks associated with unpasteurised milk and milk products (ACM/1047)

10.1 The Chair explained that the Committee had considered the risks to human health associated with M. bovis and unpasteurised milk and milk products at its last meeting but had not been able to come to a robust conclusion on the risks based on the data presented. A small group of Members had subsequently met to consider additional data provided by the Secretariat and had suggested a more formal risk assessment framework was used to present the data in a revised paper. The Chair noted that in addition to Members views on the risk assessment, views on the presentation of the document would be welcomed.

10.2 Dr Rollinson presented the revised paper explaining that it had been restructured as a formal semi-quantitative risk assessment with information presented under sections on hazard identification, hazard characterisation, exposure assessment and risk characterisation. The assessment attempted to estimate the likely number of M. bovis organisms ingested in a consumption event if contamination were present in unpasteurised milk or milk products. The data and calculations in each section of the document were outlined including key uncertainties and assumptions associated with each stage of the risk assessment. Members were asked to consider and agree to the conclusion of the risk assessment that;

  • the risk of human TB infection being acquired from unpasteurised milk and milk products has changed with the increase in M. bovis in cattle,
  • the risk to human health from M. bovis in unpasteurised cows’ milk and milk products is very low,
  • the risk to human health from M. bovis in unpasteurised sheep, goat and buffalo milk and milk products is likely to be very low however, due to a lack of data on these species there are more uncertainties associated with this assessment.

10.3 In the ensuing discussion Members agreed that the presentation of the document was helpful in assimilating the data and evaluating the conclusions presented and was a more useful way of looking at the data in a consistent manner. Members supported the conclusions made in the risk assessment. It was noted that in some cases there was difficulty in the use of terms like ‘low’ as this was a qualitative judgement dependent on consumers’ interpretation. In paragraph 53 it was noted that the second bullet should be amended to read ‘severe mastitis is likely to involve a reduction in milk production’. In relation to the unknown infectious dose for immunocompromised individuals it was suggested that this was probably, at most, the same as for the general population and likely to be considerably less.

10.4 In summarising the Chair noted that the Committee supported the conclusions of the risk assessment and found the format of the revised document much clearer. In some instances in the absence of quantitative data use of terms such as ‘low’ and ‘very low’ were all that could be supported, based on a qualitative judgement of the data. Following the minor amendments suggested by the Committee the risk assessment conclusions should go forward for consideration by the FSA Board. The Chair highlighted that the Committee would be revisiting risk assessment formats at a later date.
Action: Secretariat

11. Committee sub-groups

11.1 Professor O’Brien provided an update on the fourth and fifth meetings of the Ad Hoc Group on Foodborne Viral Infections. At their July meeting the Group had considered sewage discharges and their impact on shellfisheries and the work of the Cleaner Seas Forum. In September discussions had focussed on Environmental Health Officers’ perspectives on dealing with incidents and outbreaks of norovirus, the HPU response to norovirus outbreaks, environmental monitoring and detection methods for norovirus. Summaries of the meeting could be found on the ACMSF website. The next meeting of the Group, in October, would consider Hepatitis E.

12. Role of assessors (ACM/1036)

12.1 The Chair clarified the roles and responsibilities of ACMSF Assessors, Members and the Secretariat as recommended by the quinquennial review of the Committee. Ms Redmond suggested that the Committee consider whether it would be appropriate to have an ACMSF assessor from the Department of Health (DH) as there were overlapping DH policy interests and responsibilities on many items discussed at ACMSF. The Committee agreed this option should be explored.
Action: Secretariat

13. Dates of future meetings (ACM/1037)

13.1 Members were requested to note dates for 2012 ACMSF meetings.

Public questions and answers

14.1 The Chair drew formal proceedings to a close and invited questions and comments from the public.

14.2 Mr Alan Procter asked whether the group producing the toxoplasmosis report had considered studies which showed Toxoplasma infection had effects on human behaviour and dopamine interference. Dr Holliman responded that the group had discussed these studies but considered that the work on humans was limited to one research group and had not been verified independently and therefore took the view that there was no convincing evidence on human behaviour effects of toxoplasmosis.

14.3 Mr Tom Miller referred to information paper ACM/1042 on an FSA Review of Food Safety Behaviours in the Home and asked whether the Committee would consider a presentation on the review to ensure future ACMSF work draws on the important findings. The Chair agreed that a lot of the ACMSF’s work required a view on human behaviours, some of which had been presented in the Food and You Survey item at the last meeting, and that the review of food safety behaviours was another important report for the Committee to consider in future business.

14.4 Dr Helen Rees (ADAS) queried why she had never been given any toxoplasmosis advice when pregnant and also asked whether the body of literature on TSE persistence in soil had been looked at in development of the WRAP report on digestate. Dr Holliman noted that, in relation to advice during pregnancy, the DH policy was usually to give generic advice on food safety without naming specific pathogens. In relation to TSEs the Chair noted that the group considering the digestate report would feedback any gaps of this sort to WRAP.