Risk Profile in Relation to Toxoplasma in the Food Chain

ACMSF is a scientific advisory committee that provides the FSA with independent expert advice. This helps the Agency ensure that policy development and consumer advice, in relation to the microbiological safety of food, are based upon sound science and relevant practical experience and expertise. The committee's terms of reference are to assess the risk to humans from microorganisms that are used or occur in or on food, and to advise the FSA on any matters relating to the microbiological safety of food.

In December 2006 and March 2007, the FSA sought the views of ACMSF on the significance of toxoplasmosis in the UK.

ACMSF was asked to consider whether current evidence indicates a food safety issue that needs to be addressed, which food sources are most likely to present a significant risk, and what further investigations may be necessary to obtain robust data on UK prevalence and foodborne sources of toxoplasmosis.

The issue was referred by the full committee to the Ad Hoc Group on Vulnerable Groups, which met in December 2008 to begin its considerations on toxoplasma in the food chain. The Group met on seven occasions over a period of 28 months.

The Ad Hoc Group considered information on the prevalence of toxoplasmosis in humans, estimates of the burden of disease in the UK and other countries, seroprevalence data in farmed and non-farmed animals, and studies on the presence and survival of toxoplasma in foods. In order to review the relative importance of different sources of infection, it considered published information from outbreak reports and case control studies. The group also reviewed the consumer advice given by different countries in relation to reducing the risk of becoming infected with toxoplasma.

The information reviewed was used to produce a risk profile for toxoplasma in the UK.

The report

The Ad Hoc Group’s draft report (Annex B) has now been approved by the full Committee and is attached for comment. The structure of the report is as follows:

• Summary – an outline of the key conclusions and recommendations
• Chapter 1 summarises the background to the ACMSF’s deliberations and describes the Committee’s approach to its work
• Chapters 2 and 3 provide an introduction to Toxoplasma gondii
• Chapters 4 and 5 discuss the prevalence of human toxoplasmosis and clinical disease
• Chapter 6 examines burden of human disease
• Chapter 7 reviews information on toxoplasma carriage in farm animals, wild animals and pets
• Chapter 8 reviews studies on toxoplasma in food
• Chapter 9 discusses foodborne versus other sources of toxoplasma infection
• Chapter 10 covers existing consumer advice
• Chapter 11 summarises the data gaps highlighted by the Group together with the conclusions and recommendations from each chapter

The key conclusions and recommendations from the report are:

• Although the majority of cases of toxoplasmosis will occur in the immunocompetent, the largest burden of disease is likely to be associated with infection of immune-compromised individuals among whom symptoms are more severe and potentially life-threatening. Accurate figures are not available but it is estimated that 350,000 people become infected with toxoplasma each year in the UK, of which 10-20% are symptomatic. While the lack of accurate data for overall incidence and severity of symptoms is a barrier to achieving accurate estimates of the burden of disease and economic impact in the UK, it seems reasonable to proceed on the assumption that it will not be significantly different from the assessments made in the US and Netherlands, where the costs of the relatively small proportion of cases with severe disease make toxoplasmosis one of the most costly of gastro-intestinal infections.
  Recommendation: Further work to assess the importance of the foodborne route of infection, to identify the most important risks and appropriate risk management measures, and to refine the burden of disease assessment is justified.
  Recommendation: Risk management strategies could be focused on relevant sub-populations.

• Susceptibility of intermediate hosts to toxoplasma infection varies according to species, with seroprevalence data indicating that infection is most common in sheep, pigs and wild game. Cattle appear to be relatively resistant to infection. There is a very small amount of data on meat contamination in the UK, but virtually no data on the presence of the parasite in farm animals reared in the UK (other than a recent serological survey in sheep). Further data on seroprevalence in farm animals would be useful in monitoring the effectiveness of control measures in animal husbandry, and testing of a larger range of meat samples would be useful in identifying the main sources of risk.
  Recommendation: Further studies are recommended to establish seroprevalence in UK livestock species and to enable the outcome of these studies to be related to prevalence and levels of viable tissue cysts in edible tissues.

• Toxoplasma has been found in a wide variety of meats. However, based on the available, limited evidence, beef and housed chicken appear less commonly infected than other meat. Tachyzoites and bradyzoites are relatively fragile, whereas oocysts and tissues cysts are relatively resistant to food preparation and processing. Washing of salads and vegetables may remove some surface contamination of oocysts, whereas inactivation of the more resistant tissue cyst requires adequate cooking. Curing of meats may inactivate tissue cysts, depending on the process used.
  Recommendation: It would significantly assist risk assessment if further studies were undertaken to determine the prevalence and concentration of toxoplasma contamination in foods in the UK and to assess the effect of a number of microbiological reduction/destruction processes, for instance salad washing, milk fermentation and various meat curing methods on toxoplasma.
  Recommendation: It is also recommended that methods are developed to assess the number of viable tissue cysts in edible tissue.

• Oocyst contamination of the environment is an important risk factor in infection, and consumption of undercooked meat is also likely to be an important risk factor for pregnant women and immune-compromised groups. However, the relative contribution of food-associated toxoplasma infection is not well-defined and not known in the UK. None of the case control studies has involved cases in the UK.
  Recommendation: Given the variability in seroprevalence across Europe, differences in food handling and consumption, and in climate, a case control study in the UK should be considered.
  Recommendation: If food is confirmed as an important source of infection, better data are required on the incidence of human infection and its complications in the UK as a baseline for subsequent comparison.

• There is a variation in the consumer advice given by different countries in relation to toxoplasmosis.
  Recommendation: The current UK advice to pregnant women should be reviewed in the light of current knowledge, and the advice given by other countries.
  Recommendation: The need for similar advice for other immune-compromised groups should also be considered.

This consultation is being held for the full 12 week statutory consultation period. Comments are invited on any aspects of the draft report and its recommendations. The report is not seeking to amend legislation or provide any guidance. This consultation is not accompanied by an impact assessment because ACMSF has no regulatory status. The finalised report will be submitted by ACMSF to the FSA, and it is for the FSA to decide whether to accept the recommendations outlined in the report and whether to produce an impact assessment should the recommendations be accepted.

The Food Standards Agency aims to publish a summary of responses received within three months of the consultation ending. The ACMSF will review its draft report in the light of any comments received before submitting a final version to the FSA Chief Scientist seeking his approval for publication.

Responses are required by close 7 March 2012. Please state, in your response, whether you are responding as a private individual or on behalf of an organisation/company (including details of any stakeholders your organisation represents).

This consultation has been prepared in accordance with the HM Government Code of Practice on Consultation, which states that a consultation must follow better regulation best practice, including carrying out an Impact Assessment (Regulatory Impact Assessment in Scotland). The assessment is included in the consultation documents.

We are interested in what you thought of this consultation and would therefore welcome your general feedback on both the consultation package and overall consultation process. If you would like to assist us to improve the quality of future consultations, please feel free to share your thoughts with us by using the consultation feedback questionnaire.

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In accordance with the FSA principle of openness our Information Centre at Aviation House will hold a copy of the completed consultation. The FSA will publish a summary of responses, which may include personal data, such as your full name. Disclosure of any other personal data would be made only upon request for the full consultation responses. If you do not want this information to be released, please complete and return the Publication of Personal Data Form. Return of this form does not mean that we will treat your response to the consultation as confidential, just your personal data.

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Within three months of a consultation ending we aim to publish a summary of responses received and provide a link to it from this page.

If, after three months, the summary is still not showing, please contact the person who was responsible for the original consultation. Alternatively, you can contact the FSA Consultation Co-ordinator by email: consultationcoordinator@foodstandards.gsi.gov.uk