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5 May 2003, Rome
-- The spread of the Severe Acute Respiratory
Syndrome (SARS) virus has caused major concern around the world.
There has been media speculation that intensive livestock
production might be a breeding ground for the virus.
Peter Roeder, FAO Animal Production and Health
Division, comments on the potential link between agriculture,
livestock production and the SARS pandemic.
Is there any proof that the SARS virus
originated in animals?
There is
currently no evidence for an origin in farm animals (cattle,
pigs, poultry etc) and it seems unlikely, even if the origin of
the virus is still a mystery.
Assuming
that SARS is caused by the novel coronavirus which has been
associated with the disease, genetic fingerprinting of this
virus shows it to be very different from any other known animal
or human coronavirus.
Is there
any relationship between SARS and the bird flu currently active
in Europe and the US?
No, these
are caused by two completely different viruses.
Are intensive livestock production and the
concentration of animals to blame as a breeding ground for
SARS?
Intuitively one might
expect this to be the case but, as there is no evidence that the
virus originated in farm animals, these factors cannot be held
responsible on this occasion.
The high
population density in southern China could well have been an
important factor in the genesis of this disease, whatever its
origin.
Could a more sustainable
livestock production reduce the risk of such diseases?
This is certainly so, but it is not a
factor in this case.
That said, the
vulnerability to epidemic diseases of intensive, industrialised
livestock farming systems is increasingly being demonstrated.
This brings into doubt the viability of these systems.
A high human population density in close
contact with several species of intensively farmed livestock
potentially provides a substrate for cross-species transmission,
evolution and amplification of many pathogenic agents.
Scientists in Canada and Australia
are planning to import the SARS virus and infect animals with
it. FAO is supporting these experiments. What do you expect from
these tests?
This experimental
work is needed to match field studies to explore the unlikely
circulation of the virus in animal populations.
The work has actually started at the Canadian National
Centre for Foreign Animal Disease and we hope it will be
complemented by other studies in Australia. We expect that this
work will tell us about the potential for this virus to infect
animals, the nature of any disease signs produced and the
potential for animals to pass on the virus.
Could the virus be transmitted through
livestock products and trade
We
have no evidence that the SARS virus infects farm animals and,
thus, its presence in animals and food products is highly
speculative. Even if present, the virus would most probably be
completely killed by cooking and processing.
The coronaviruses, to which the SARS agent probably
belongs, tend to be rather fragile outside animals and would
last for only a short time - a matter of only a few hours - as
contaminants on food packaging.
There
seems to be no reason to suspect that livestock trade has been
the way this disease has spread within affected areas and around
the world.
All the evidence points to this
being a human pathogen transmitted primarily by droplet
infection from the respiratory tract of affected people.
Could trade restrictions help to
stop the spread of the virus?
Trade seems not to play a role, so trade restrictions
are irrelevant.
Could the virus be
transported through food products carried by
travellers?
Again the answer
seems to be a clear 'No'.
What's FAO's role in fighting
SARS?
FAO is first of all
concerned to ensure that a full and complete characterisation of
the SARS agent and its evolution iscarried out. The involvement
of farm animals and trade must be ruled out.
In partnership with WHO, FAO pays particular attention
to the farming and food handling context. On a more generic
level the evolution of pathogenic agents in intensive farming
systems in highly populated areas is a matter of ongoing concern
for FAO.
Understanding the evolution of
pathogens in relation to farming systems and the food chain is
an important component of FAO's work in veterinary public
health.
Contact:
Erwin Northoff
Information Officer, FAO
erwin.northoff@fao.org
(+39) 06 570
53105
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