Download Disease related risk factors

Department for Environment Food and Rural Affairs
Consultation on the transposition of Council Directive
2002/99/EC on Meat Hygiene
January 2007
Veterinary Risk Assessment
Veterinary Advice on the Likelihood of Transmission of
Disease Arising from the Different Options for the
Transposition of the EU Council Directive 2002 (2002/99/EC)
Executive summary
1. It is important to note that in the context of this Directive, the hazard is most correctly
the infectious agent of the specified disease contaminating the meat e.g. foot and
mouth disease virus or african swine fever virus; however, for risk management
purposes it may more appropriately be considered to be the meat originating from a
protection (PZ) or surveillance zones (SZ).
2. The risk of disease transmission arises from the ingestion by other animals of the
meat produced from viraemic animals with un-disclosed disease, within the PZ and
SZ surrounding an infected premises (IP).
3. The critical control points to reduce the likelihood of the spread of the hazard are:
a) The stamping of meat and meat products from a PZ or SZ with the appropriate
health mark, without which the meat would become indistinguishable from
meat not originating from the PZ and SZ .
b) The monitoring and enforcement of treatment standards.
c) The monitoring and enforcement of checks on both stamped and unstamped
fresh meat.
4. The critical control point for the reduction of the likelihood of transmission of
disease from meat is one or more of the appropriate treatment as described in annex
II of Council Directive 2002/99/EC.
5. It should be noted that if the product has been treated using one of the proscribed
approved methods, the likelihood of viable virus being present should be negligible.
Stamping of meat will achieve no further reduction in disease risk, but will enhance
traceability of the product if there has been a failure of the treatment regime.
6. Veterinary advice is that the controls described in option two are the most likely to
prevent additional outbreaks of disease within the UK. These could occur many
months after the initial incident, resulting from infected meat products stored within
the production and supply chain.
7. The source of one IP is the spread from another; and when this Directive is enforced
in all EU Member States (MS), there is thus a mutual benefit, as it will reduce the risk
of UK importing infection from the PZ and SZ of IPs in other MSs as it will allow the
identification of meat from these areas and facilitate the enforcement of treatment
standards.
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Introduction
8. The aim of the rules in 2002/99/EC is to prevent the introduction or spread of animal
diseases resulting from the placing on the market of products of animal origin
(POAO) originating from a holding or area infected by epizootic diseases and the
obligation to subject products coming from PZ or SZ areas to treatment to destroy the
disease agent.
9. The risk of disease transmission arises from meat produced from viraemic animals,
with un-disclosed disease, in the protection (PZ) and surveillance zones (SZ)
surrounding an infected premises (IP).
10. The agents of interest in this context are those for:
a) Rinderpest (RP).
b) Peste de petit ruminants (PPR).
c) African swine fever (ASF).
d) Swine vesicular disease (SVD).
e) Newcastle disease (ND).
f)
Classical Swine Fever (CSF)
g) Please note that foot and mouth disease (FMD) and avian influenza (AI) are
dealt with in separate legislation.
11. For the purpose of this risk assessment, it is assumed that disease is present on at
least one GB premises (IP) and has been detected (until the outbreak has been
detected, the legislation could not be used. Therefore, it does not consider a release
assessment for any of the diseases, but concentrates on exposure and consequence
assessment.
12. This veterinary advice considers the risk arising from the movement and potential
consumption of meat or meat products from the surrounding SZ or PZ of an infected
premises (IP).
13. The source of one IP is the spread from another; and when this Directive is enforced
in all EU Member States (MS), there is thus a mutual benefit, as it will reduce the risk
of UK importing infection in untreated meat originating from the PZ and SZ of IPs in
other MS’s.
Hazard identification
14. For risk management purposes the hazard may more appropriately be considered to
be the meat originating from a protection (PZ) or surveillance zones (SZ), rather than
the infectious agent of the specified disease contaminating possibly contaminating
the meat.
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Figure 1: H4 - Stages of meat production and processing subject to official control
Cold
Store
Cutting Plant
Co-located with
Meat Processing
plant
Abattoir
Meat
Processing
Plant
(Cooked)
Cutting Plant
Co-located with
abattoir
MHS control
LA control
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Control
ceases
The options considered in this document
a) Option 1: Do nothing; do not implement any control measures.
b) Option 2: Transpose the Directive exactly.
c) Option 3: Impose restrictions on products of animal origin from PZs and SZs..
The risk question addressed in this document
15. How effective are the specified three options in reducing the likelihood of disease
transmission via meat produced from animals in the SZ or PZ to other susceptible
livestock?
16. Based on the hazard being the meat originating in a PZ or SZ, this veterinary risk
assessment has been simplified to consider the risk due to CSF only.
17. CSF has been selected because historical records and disease risk modelling have
shown that CSF is the most likely of the diseases to cause an outbreak in UK, the CSF
virus has the following characteristics:
a) Widely distributed in the carcase of an infected animal.
b) Infectious by the oral route.
c) Has a very low oral infectious dose.
d) Capable of surviving for extended periods in some meat and meat products.
e) Relatively stable and resistant to disinfection.
18. CSF is thus the disease most likely to give rise to outbreaks as a result of “leaks” from
the system of controls required by 2002/99/EC.
Summary of the major risk factors for the transmission
of disease to susceptible species:
Disease related risk factors
19. The following disease related risk factors will have an effect on the likelihood of
transmission of disease to susceptible animals:
a) It is important to note that the likelihood of transmission of disease from the
movement of meat or meat products is orders of magnitude less than that
resulting from the movement of infected live animals.
b) The CSF virus is resistant to disinfection and can survive for considerable periods
of time in the environment and in uncooked and preserved meats, such as salami
and ham.
c) CSF can be transmitted orally and the oral infectious dose is extremely low.
Susceptible host related risk factors
20. The following susceptible host related risk factors will have an effect on the likelihood of
transmission of disease to susceptible animals:
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a) The source of the risk is meat and meat products, thus infection would have to
be by the oral route i.e. they would have to be eaten.
b) Therefore, the ban on swill feeding is significant.
c) Behavioural studies have shown that herbivores such as cattle and sheep are
unlikely to consume meat products, unless they have been transformed in some
way (e.g. minced and mixed with other feed).
d) The need for oral consumption of the product therefore restricts the likely
susceptible population to pigs or poultry.
e) The risk diseases of relevance to H4 are mainly those diseases that affect
pigs.
Animal management related risk factors
21. The following animal management related risk factors will have an effect on the
likelihood of transmission of disease to susceptible animals:
a) The geographical distribution of the industry in UK
b) The ban on swill feeding.
c) CSF is not windborne over substantial distances.
d) Movement controls: Identification, registration of premises and stringent
movement controls for live pigs.
e) The centralised control of the industry and the general high standards of
husbandry and management.
f)
The vertical integration of the intensive productions systems (production pyramid)
and the absence of markets.
g) The age batching of pigs in the production process.
h) The high-level so biosecurity present in the industry.
i)
The high levels of health and production monitoring which are the norm in the
industry.
j)
Ante and post-mortem inspection at slaughter.
k) Wild boar which are the main wildlife host for CSF in Europe, are currently
present in the UK in very restricted areas, at relatively small population densities;
however, it would be possible for an isolated wild boar population to become
infected, maintain that infection and for this to spill over to commercial pig herds;
especially if these are managed outside as free-range units.
l)
The number of backyard and pet pigs are currently not well known, however, it
is likely that these are small in number and dispersed. Although legislation forbids
feeding such animals using catering and household waste (swill), the lack of
knowledge of their keepers makes them a potentially a serious source of disease
risk.
Product management related risk factors
22. The following product management related risk factors will have an effect on the
likelihood of transmission of disease to susceptible animals:
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a) The health marking of the meat or meat product to indicate that it originated from
a PZ or SZ.
b) Treatment of the product as per annex III of Council Directive 2002/99/EC.
c) Official controls.
Summary of the risk management options
Managing the disease agent related risk factors
23. The disease related risk factors can be managed by managing the agent through
treatment of the product and avoiding the risk of contact between pigs and untreated
product.
Managing the susceptible host related risk factors
24. As discussed above, susceptibility of the host population is determined by behaviour.
The implementation and enforcement of the swill feeding ban is important in
reducing the risk of disease transmission.
Managing the animal management related risk factors
25. The normal management practices described above that are inherent within the
UK pig industry mitigate much of the risk. However, three important risks require to
be managed: (i) outdoor pigs, (ii) wild boar and (iii) back-yard/pet pigs. The most
important aid to mitigation of the risk in this class is increasing public education and
awareness of:
a) the need to register pigs and their movement and
b) the dangers (and illegality) of feeding both food fit for human consumption and
food waste to pigs.
Managing the product management risk factors
Discussion of the risk management options
26. If there are no restrictions on meat or meat products the scale of the outbreak is likely to
be of an unpredictably longer duration and to be more dispersed geographically.
a) The increased duration may be particularly unpredictable and outbreaks
sporadic due to the ability of CSF to survive for considerable periods of time in
uncooked or preserved meats that may sit in the food chain for many months.
b) However, it is important to note that in order to pose a risk, the meat has to be
eaten by a pig. Introduction to the pig population by the route of meat and meat
products originating in a PZ or SZ is likely to be restricted to:

Outdoor pigs illegally fed “over the fence”.

Scavenging wild-boar.

Back-yard / pet pigs that are illegally fed kitchen waste.
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c) Back-yard / pet pigs are likely to give rise to isolated outbreaks or may even fail
to pass on infection to other pigs due to the lack of opportunity. Scavenging wildboar could potentially maintain infection independently; which would then only
become apparent if it spilled over into commercial pigs.
27. Introduction of disease to the intensive, indoor pig production sector is unlikely for
the reasons discussed above.
Scale of outbreak – directive/ H4 implemented with option 2
controls.
28. If option two controls are imposed, the scale of the outbreak will be independent of the
movement on meat, and will influenced only by other factors.
a) Adherence to option 2 controls would reduce to negligible the risk to both UK and
other MS’s from uncooked or preserved meat. The risk remains negligible rather
than zero due to the possibility of illegal movement of meat outside official
controls.
b) All residual risk to UK and other MS is negated by full implementation and
enforcement of the ban on swill feeding.
Scale of outbreak – directive/ H4 implemented with option 3
controls
29. If option three controls are implemented, this would expose the UK to the same level of
risk as option 1, but would protect export markets to the same extent as option 2.
Conclusions and recommendations
30. Veterinary advice is that the controls described in option two are the most likely to
prevent additional outbreaks of disease within the UK. These have the potential to occur
many months after the initial incident (especially in the case of resistant infectious
agents such as CSF virus), resulting from infected meat products stored within the
production and supply chain.
31. The critical control point for the reduction of the likelihood of transmission of disease
from meat and meat products is the appropriate treatment as described in annex II of
Council Directive 2002/99/EC.
32. Veterinary advice is that the critical control points to reduce the likelihood of the spread
of the hazard are:
c) The stamping of fresh meat from a PZ or SZ with the appropriate health mark,
without which the meat would become indistinguishable from meat not originating
from the PZ and SZ.
d) The monitoring and enforcement of treatment standards, and official controls.
e) The monitoring and enforcement of checks for both stamped and unstamped
fresh meat outside the production chain.
33. It should be noted that if the product has been treated using one of the proscribed
approved methods, the likelihood of viable virus should be negligible. Stamping of such
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meat products will achieve no further reduction in disease risk, but will enhance
traceability if there has been a failure of the treatment regime.
Andrew Paterson
AHTBD
16 June 2006
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