Foodborne Viruses and Prions and Their Significance for Public Health PDF
Preview Foodborne Viruses and Prions and Their Significance for Public Health
Food safety assurance and veterinary public health – volume 6 – Foodborne viruses and prions and their significance for public health edited by: Frans J.M. Smulders Birgit Nørrung Herbert Budka Foodborne viruses and prions and their significance for public health EE CC VVPPHH Food safety assurance and veterinary public health – volume 6 – Foodborne viruses and prions and their significance for public health edited by: Frans J.M. Smulders Birgit Nørrung Herbert Budka Wageningen Academic P u b l i s h e r s Buy a print copy of this book at www.WageningenAcademic.com/safety6 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned. Nothing from this publication may be translated, reproduced, stored in a computerised system or published in any form or in any manner, including electronic, mechanical, reprographic or photographic, without prior written permission from the publisher, Wageningen Academic Publishers, ISBN: 978-90-8686-226-9 P.O. Box 220, 6700 AE Wageningen, e-ISBN: 978-90-8686-780-6 the Netherlands, DOI: 10.3920/978-90-8686-780-6 www.WageningenAcademic.com [email protected] ISSN 1871-9295 The individual contributions in this publication and any liabilities arising from them remain the responsibility of First published, 2013 the authors. The publisher is not responsible for © Wageningen Academic Publishers possible damages, which could be a result The Netherlands, 2013 of content derived from this publication. Preface Over the past decade a total of five volumes of the book series ‘Food Safety Assurance and Veterinary Public Health’ have been issued by Wageningen Academic Publishers. These are volume 1: ‘Food safety assurance in the pre-harvest phase’ (2002); volume 2: ‘Safety assurance during food processing’ (2004); volume 3: ‘Risk management strategies: monitoring and surveillance’ (2005); volume 4: ‘Towards a risk-based chain control’ (2006); and finally volume 5: ‘Welfare of production animals: assessment and management of risks’ (2009). Volume 6 now lies in front of you. The primary target audience of the series are scientists – in academia and industry – involved in animal production, students of veterinary and food science and governmental officials (risk managers) in veterinary public health and food safety. This focus has prompted the editors to pay attention to issues with high relevance for public health and the food trade (continually addressed by food safety authorities worldwide), thus providing reliable, topical and updated reference material. The international Codex Alimentarius Commission has defined food safety hazards to include those of a biological, chemical and physical nature (Codex Alimentarius Commission, 2007). Veterinarians are generally engaged with the first category and arguably appear to be primarily aware of microbiological hazards (particularly pathogenic and spoilage bacteria) that jeopardize the safety and shelf life of foods. This is undoubtedly associated with the fact that veterinary training often focusses on food production by domestic species, which are known to transfer bacterial agents to foods of animal origin, such as meat and milk and the products manufactured therefrom. Although viruses clearly play an important part in clinical and preventive veterinary medicine as the causative agents of viral animal diseases with zoonotic potential, foodborne viruses have often been neglected. The main reason for the neglect is that foodborne viral outbreaks – with few exceptions (notably hepatitis E and tick-borne encephalitis virus, which are transmitted via the consumption of undercooked pork and raw milk, respectively) – are caused by viruses that originate in the human reservoir. At the EU level it is unknown how much disease caused by Norovirus can be attributed to foodborne spread. Studies in some countries suggest that this route of transmission may be significant and there is clear evidence of significant underreporting of foodborne outbreaks. Moreover, although background data from case reports of hepatitis A are often insufficient to prove foodborne transmission, occasional outbreaks have been documented (EFSA, 2011). According to records of the European Food Safety Authority (2012) it appears that around 15% of reported foodborne disease outbreaks are caused by viruses (comprising cases attributable to both foods of animal and of non-animal origin). The current trend towards the production of ready-to-eat meals, which consist of a mixture of ingredients from various sources and geographical regions, poses a further health threat. Veterinarians – whether employed by industry or serving as governmental officials commissioned to inspect and audit food manufacturing enterprises – should be aware of the public health risks associated with viruses in food ingredients and the food processing and catering environment, and of the Foodborne viruses and prions and their significance for public health 7 grave consequences for industry and international trade in the event of serious viral disease outbreaks. Until the early 1980’s many researchers believed that the group of neurodegenerative diseases called ‘transmissible spongiform encephalopathies’ (TSE’s) had a viral aetiology. Since then it has been convincingly demonstrated that the infectious particles responsible for TSE’s are devoid of nucleic acids but contain an abnormal isoform of host-encoded protein, the prion protein. Over the subsequent decades, prions known to be transferred via foods, notably the bovine spongiform encephalopathy (BSE) agent, have been the cause of widespread public concern. The public has been particularly sensitive to the danger since 1996, when it was announced that BSE was possibly linked to the contraction of ‘new variant Creuzfeldt Jacob disease’ (nv-CJD) in humans. Consumer confidence in the UK fell to an all-time low and the impact of the BSE crisis on the British economy in the period 1996-1998 was enormous, with an estimated loss of around 3.5 billion pounds sterling (Atkinson, 2013). It seems timely that, even decades later, updated information on prions should be made available. The editors of this volume have been active in various scientific panels and chairing working groups of the EFSA on foodborne viruses and on prions and so were in the fortunate position of being able to recruit recognised experts from their networks to address the specific issues covered in the book. We are very grateful for the experts’ willingness to oblige by contributing to this volume and for adhering to the rather strict instructions for authors. Last, but certainly not least, we are indebted to Alexandra Bauer, DVM, PhD – our desk-editor – whose invaluable support, as always, has been exemplary. We hope the results of our efforts will help educate the less familiar members of readership while serving as a useful reference manual for the more learned. Vienna, Copenhagen and Zürich, February 2013. Frans Smulders, Birgit Nørrung and Herbert Budka References Atkinson, N., 2013. The impact of BSE on the UK economy. Available at: www.veterinaria.org/revistas/vetenfinf/ bse/atkinson.html. Codex Alimentarius Commission (CAC), 2007. Principles and guidelines for the conduct of microbiological risk assessment. Document CAC/GL 63-2007, FAO/WHO, Rome, Italy. European Food Safety Authority (EFSA), 2011. Scientific opinion of the Scientific Panel on Biological Hazards (BIOHAZ) on an update of the present knowledge on the occurrence and control of foodborne viruses. EFSA Journal 9, 2190, 96 pp. European Food Safety Authority(EFSA), 2012. The European Union summary report on trends and sources of zoonoses, zoonotic agents and food-borne outbreaks in the European Union in 2010. EFSA Journal 10, 2597, 442pp. 8 Foodborne viruses and prions and their significance for public health Contents Table of contents Preface 7 References 8 Part 1 - Viruses Viruses: the basics 17 Mohammad Y. Halami, Kristin Heenemann, Daniel Hoffmann and Thomas W. Vahlenkamp Summary 17 1. Introduction 17 2. Virus classification, structure and function 18 3. Virus replication 21 4. Virus receptors and virus transmission 22 5. Laboratory diagnosis of virus infections 24 6. Outcome of viral infections 27 7. Virus disease in humans and animals 31 8. Conclusions 32 Acknowledgements 34 References 34 Foodborne viruses: an introduction 37 Birgit Nørrung References 40 Introduction to norovirus 41 Janko van Beek and Marion Koopmans Summary 41 1. Introduction 41 2. Norovirus characteristics 42 3. Norovirus diagnoses and surveillance 45 4. Prevalence and epidemiology 47 5. Immunity and host resistance 50 6. Prevention and control 52 7. Conclusions 53 References 54 Hepatitis A virus 61 Albert Bosch and Rosa M. Pintó Summary 61 1. Introduction 61 2. Hepatitis A virus features 63 3. Hepatitis A virus transmission; waterborne and foodborne transmission 66 4. Genetic variability of hepatitis A virus 66 Foodborne viruses and prions and their significance for public health 9
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