Viral Zoonoses and Food of Animal Origin: A Re-Evaluation of Possible Hazards for Human Health

255 Pages·1997·5.58 MB·English

by  Dr. D. Baxby

O.-R. Kaaden
C.-P. Czerny
W Eichhorn (eds.)
Viral Zoonoses and
Food ofAnimal Origin
A Re-Evaluation of
Possible Hazards
for Human Health
Springer-Verlag Wien GmbH
Praf. Dr. Oskar-RugerKaaden
Dr. Claus-PeterCzemy
Dr. WemerEichhom
InstituteofMedicalMicrobiology,Ludwig-Maximilians-University,
Munich, FederalRepublicofGermany
This workissubjecttocopyright.
Allrights arereserved,whetherthewhole Ofpart ofthematerialisconcemed,specificallythose oftranslation,
reprinting,re-useofillustrations,broadcasting,reproductionbyphotocopyingmachinesorsimilar means,
andstorage indatabanks.
© 1997Springer-VerlagWien
OriginallypublishedbySpringer-VerlagWienNewYorkin1997
Softcoverreprintofthehardcover1stedition1997
Typesetting:ThomsonPress (India) Ltd., NewDelhi
Graphic design: Ecke Bonk
Printedonacid-freeandchlorine-freebleachedpaper
SPIN: 10558738
With 43Figures
ISBN978-3-211-83014-7 ISBN978-3-7091-6534-8 (eBook)
DOI 10.1007/978-3-7091-6534-8
"Viral Zoonoses and Food of Animal Origin: ARe-Evaluation
of Possible Hazards for Human Health"
Opening Speech
On behalf of the Federal Minister for Health, Mr. Horst Seehofer, and of the Federal
Minister of Food, Agriculture and Forestry, Mr. 10chen Borchert, I would like to
give you a warm welcome today to the 9th Munich Symposium on Microbiology
from the "WHO Collaborating Centre for Collection and Evaluation of Data on
Comparative Virology", Institute for Medical Microbiology, Infectious and Epi
demic Diseases, Veterinary Faculty, Ludwig-Maximilians-University of Munich on
the subject "Viral Zoonoses and Food of Animal Origin: A Re-Evaluation of
Possible Hazards for Human Health".
In Central Europe and especially in Germany, it is an old tradition to consume
various kinds of food of animal origin raw. Minced meat made of raw beef ('Tatar")
and uncooked pork ("Hackepeter") are hardly ever missing from a country-style
buffet. Certified milk, i.e. cows' milk intended for raw consumption and soft cheese
manufactured from raw milk are also popular specialities. Live oysters or sabajone
and "Bienenstich" cake with cream made from raw eggs are now standard dishes in
every Italian restaurant in Germany.
It is reasonable to presume that statutory bans will hardly alter these old
traditions of food consumption. Furthermore, a prohibition of selling such raw food
would be evaded and the sale would be continued without any control. Moreover, it
has to be expected that recommendations for the consumers to change their dietary
habits will not have any effect.
On the basis of these practical reflections the legislator permitted, by virtue of
legal provisions and within a clearly restricted framework, the manufacture and
marketing of raw food of animal origin and subjected them to stringent precautions
and requirements. In doing so, however, he also assumes responsibility for possible
negative effects of this permission, e.g. for diseases arising from animal-borne
zoonoses communicated to man via food.
However, general dietary habits also carry risks with regard to possible second
ary and cross-contamination. Additionally, attention should be given to the rel
evance of direct contact between animals and people to the infection chain.
Therefore, prior to every statutory food-hygiene-admission and also in future,
the risk involved must be estimated as exactly as possible and the best possible
measures of restricting this risk must be ascertained.
VI Opening Speech
It is mainly scientists and practicians who must deal with these questions. Thus
the Federal Government is very grateful to the WHO-Collaborating Centre for
Collection and Evaluation of Data on Comparative Virology for taking up this
important subject.
We particularly appreciate the fact that you, ladies and gentlemen, have come to
Munich to discuss this issue and to formulate recommendations. You are assisting us
- the law-giving bodies - in judging to what extent food of animal origin can be
consumed and where the limits are with regard to the risks involved in doing so. But
you are also helping the producers of these foods and the controlling bodies to
realize how and by what measures these risks can be minimized.
Each year for over 20 years now, the Federal Government has, in collaboration with
the WHO, been supporting individual programmes aimed at clarifying the behaviour
of zoonoses and identifying means of controlling them. The reports of these confer
ences are available from the Headquarter of the World Health Organization in Geneva.
The Federal Ministry for Health has contributed 55 .000 DM to help make this con
ference a success. I am convinced that this was a worthwile investment since the com
position of this assembly gives us reason, to assume that your results will .have a
meaningful influence on the legislative work in your countries and in ours.
This event was organised by the WHO-Collaborating Centre, represented today
by Professor Kaaden. I would like to give our special thanks to you and your
colleagues for this achievement.
The Federal Government hopes to contribute to improving world health not only
through its annual contribution to the World Health Organization of about 55 million
DM, but also through the concrete measures it takes to find solutions to problems,
these measures being financed with the aid of supplementary funds. One example of
the latter is, for instance, the sum of approximately 2.5 million DM allocated
annually for the WHO Collaboration Centers and for this kind of meeting.
Our goal is, through the exchange of opinions and knowledge which is taking
place here today, to be able to identify health hazards in advance and ward off
possible threats to human and animal health.
The governments of various countries including those comprising the European
Union are awaiting the results of this conference with great interest. They are
looking forward to obtaining results which they can use as a basis on which to
examine their standards and, where necessary, make adjustments.
Not least due to this, I wish you the greatest posssible success in your endeavours
today and tomorrow here in Munich and hereby declare this conference open.
Dr. Hans Bohm
Federal Ministry for Health, Bonn
Acknowledgement
The Editors gratefully acknowledge the competent and skilledl secretarial assistance
of Mrs. Elke Bongers to organize the 9th Munich Symposium on Microbiology and
to publish the scientific papers as supplement to Archives of Virology.
Contents
Baxby, D., Bennett, M.: Cowpox: a re-evaluation of the risks of human cowpox
based on new epidemiological information ............................ 1
Czerny, C.-P., Zeller-Lue, C., Eis-Hubinger, A. M., Kaaden O.-R., Meyer, H.:
Characterization of a cowpox-like orthopox virus which had caused a lethal
infection in man ................................................. 13
Mercer, A., Fleming, S., Robinson, A., Nettleton, P., Reid, H.: Molecular genetic
analyses of parapoxviruses pathogenic for humans . . . . . . . . . . . . . . . . . . . . . . 25
Bugert, J. J., Darai, G.: Recent advances in molluscum contagiosum virus
research .............. : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Tidona, C. A., Darai, G.: Molecular anatomy of lymphocystis disease virus .... 49
Buttner, M., Oehmig, A., Weiland, F., Rziha, H.-J., Pfaff, E.: Detection of virus
or virus specific nucleic acid in foodstuff or bioproducts - hazards and risk
assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Pillai, S. D.: Rapid molecular detection of microbial pathogens: breakthroughs
and challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Muller, W. W.: Where do we stand with oral vaccination of foxes against rabies in
Europe? ........................................................ 83
Bauer, K.: Foot-and-mouth disease as zoonosis ........................... 95
Schoitissek, c.: Molecular epidemiology of influenza ...................... 99
Webster, R. G.: Influenza virus: transmission between species and relevance to
emergence of the next human pandemic .............................. 105
Deng, R., Mirza, A. M., Mahon, P. J., Iorio, R. M.: Functional chimeric HN
glycoproteins derived from Newcastle disease virus and human parainfluenza
virus-3 ......................................................... 115
Desselberger, U.: Viral factors determining rotavirus pathogenicity ........... 131
Clarke, I. N., Lambden, P. R.: Viral zoonoses and food of animal origin:
caliciviruses and human disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Green, K. Y.: The role of human caliciviruses in epidemic gastroenteritis. . . . . . . 153
Bode, L., Ludwig, H.: Clinical similarities and close genetic relationship of
human and animal Borna disease virus ............................... 167
Herzog, S., Pfeuffer, I., Haberzettl, K., Feldmann, H., Frese, K., Bechter, K.,
Richt, J. A.: Molecular characterization of Borna disease virus from naturally
infected animals and possible links to human disorders .................. 183
Le Guenno, B.: Haemorrhagic fevers and ecological perturbations ............ 191
Sawitzky, D.: Transmission, species specificity, and pathogenicity of Aujeszky's
disease virus .................................................... 201
VIII Contents
Stohr, K., Meslin, F. X.: The role of veterinary public health in the prevention of
zoonoses ....................................................... 207
Stolle, A., Sperner, B.: Viral infections transmitted by food of animal origin: the
present situation in the European Union .............................. 219
Siiss, J., Beziat, P., Schrader, Ch.: Viral zoonosis from the viewpoint of their
epidemiological surveillance: tick-borne encephalitis as a model .......... 229
Werz, W., Hoffmann, H., Haberer, K., Waiter, J. K.: Strategies to avoid virus
transmissions by biopharmaceutic products . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
Cowpox: a re-evaluation of the risks of human cowpox
based on new epidemiological information
D. Baxbyl and M. Bennett2
1 Alder Hey Childrens' Hospital and Department of Medical Microbiology,
Liverpool University, Liverpool, U.K.
2Department of Veterinary Clinical Science, Liverpool University,
Liverpool, U.K.
Summary. Human cowpox is a rare but relatively severe infection of interest
because of its links with Edward Jenner and the introduction of smallpox
vaccine and, more recently, because of re-evaluation of the epidemiology of the
infection. This indicates that cowpox is not enzootic in cattle, relegates the cow
to a minor role, and emphasizes the importance of feline cowpox as a source of
human infection and of wildlife as virus reservoirs. The evidence available
suggests that the virus is of low infectivity for humans and should not become
an increasing problem despite the cessation of smallpox vaccination and
increasing numbers of immunocompromised individuals.
Introduction
Attention was first drawn to cowpox in Edward Jenner's famous Inquiry of
1798, when he reported his cowpox inoculation (vaccination) experiments, the
first of which was done 200 years ago on May 14, 1796 [4, 6, 30]. Jenner
provided a coloured plate illustrating natural human cowpox and, particularly in
a later monograph [31], distinguished between 'true' and 'spurious' cowpox.
The latter, which would not protect against smallpox, included what we would
now recognize as pseudocowpox (milker's nodes) caused by a parapoxvirus
antigenically unrelated to cowpox virus [4, 24].
During the early 19th century, when epidemiological studies were largely
unknown, the germ theory of disease not established and laboratory help not
available, cowpox was regarded as a natural disease of cattle with a bovine
reservoir; hence the name, cowpox. The view that cowpox was enzootic in
cattle persisted until the 1970s, although it was recognized that bovine cowpox
was uncommon [16, 42]. It was also natural that, reflecting these views,
human cowpox was regarded as an occupational hazard of dairyworkers etc.
However, studies since then and reviewed here indicate that cowpox virus,
which has a wide host range, has wildlife reservoirs and is seen most often in
domestic cats.
2 D. Baxby and M. Bennett
This paper re-evaluates the risk of human cowpox im the light of this
information, the declining residual immunity provided by smallpox vaccina
tion, and the increasing proportion of immunocompromised individuals in the
community.
Human cowpox
Human cowpox is rare, and although individual cases were described, there was
no attempt to collate clinical and epidemiological infonnation on different
cases until the authors' survey of ten human cases in 1977 [2]. This was
extended to 54 cases by 1993, by which time mor~ certain information was
available on severity, age, sex, number and location of lesions, and particularly
on the source of infection [5].
Infection is through a break in the skin and this determines the location of
the primary lesion (Table 1). The hand is most commonly affected, but a
relatively high proportion of patients (39%) had facial lesions and in 16% the
eye was involved. There was a preponderance of adolescent males with facial
lesions which may be connected with poor shaving technique or puberty.
The majority of patients have only one lesion. Additional lesions may be
coprimaries [9, 48] or occasional secondary lesions caused by accidental
transfer from a developing primary lesion [9,48]. More rarely, multiple lesions
may be due to lymphatic or viraemic spread [9,43]. Generalized infections are
rare and occur only in patients with predisposing factors such as immunode
fiency, eczema or dermatitis [9, 22, 32].
The lesions which are invariably painful start as inflamed macules and pass
through papules and haemorrhagic vesicles over a period of 7-12 days. Cases
are rarely seen at this stage and by the time they are, usually after 2-3 weeks,
the lesion will have progressed to a hard black eschar (for colour illustrations
see [9]). Inflammation, oedema, and lymphadenopathy are common and most
Table 1. Human cowpox: location of lesions in relation to age and sex of patient
(54 cases)a
Location Age (years)b
< 12 12-18 >18
m f m f m f Total (%)
Hands only 2 5 0 2 8 8 25 (46)
Face only 1 3 4 2 5 3 18 (33)
Hands & face 0 1 0 0 0 0 1 (2)
Miscc 0 2 0 1 3 1 7 (l3)
Generalized 0 0 2 0 1 0 3 (6)
Total 3 11 6 5 17 12 54
aFram data in [9]
bA ge range 1-64 years
cFor example elbow, knee, anogenital
A re-evaluation of the risks of human cowpox 3
patients report some systemic reaction such as pyrexia, malaise, lethargy, sore
throat, and/or 'flu-like' symptoms. Sixteen out of 54 patients (30%) of whom 9
were <18 years were admitted to hospital for periods of between 3 and 24 days,
and most others were absent from school or work and required bed-rest.
The majority of patients recover in 6-8 weeks although in some, complete
healing may take 10-12 weeks or longer. Scarring is common and permanent,
and cosmetic surgery may be considered for facial scars. Eye infections may
result in conjunctivitis sometimes with corneal involvement; recovery is
complete though often slow [9]. Rare deaths due to encephalitis or generalized
infection have been recorded [9, 22]. In general, treatment is supportive with
antibiotics used to control any secondary bacterial infection. Corticosteroids
exacerbate the infection and Acyclovir is ineffective against poxvirus infection.
The most important differential diagnoses are: milker's nodes which is
usually less painful and in which a bovine source can often be traced; herpes
simplex, usually less haemorrhagic and erythematous and which should be
recognized if it is a reactivation; and cutaneous anthrax, relatively painless and
rare in Britain [9]. Electron microscopy can be of great value. All but one of 24
cases from which suitable material was available were diagnosed by this
method [9]. Epidemiological features which might suggest cowpox include;
involvement of all age groups, but perhaps more commonly young girls
(Table 1); presentation particularly during July to November; and, as discussed
below, contact with domestic cats [9, 12].
Epidemiology of cowpox
Bovine cowpox
Although there is evidence that bovine cowpox was uncommon during the 19th
century [4] the idea that cows were the reservoir host persisted. Consequently
when viruses were isolated from human and bovine cases and shown to be
different from other poxviruses [23, 24] the term cowpox virus was adopted.
However there is now strong evidence that cows are not the reservoir host of
cowpox virus (Table 2).
Table 2. Sources of 56 cases of human cowpox
1969-93a
Source Total %
Unknownb 26 46
Feline b 18 32
OccupationalC 7 12.5
Bovine 3 5
Rodentsd 2 3.6
aFrom data in [9, 50]
bFor 1985-93 unknown = 30%, feline = 55%
CVeterinary, laboratory and zoo workers
dCircumstantial evidence only