Table Of ContentFood 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
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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
