Supplementary memorandum from the Department
for Environment, Food and Rural Affairs
During the course of the session Jim Scudamore
offered to provide the Committee with some additional information.
The Parliamentary Secretary, Elliot Morley has written to the
Chairman separately about two of those points, namely details
of the plans being drawn up to combat the illegal importation
of meat (Questions 36 to 38); and details of whether or not a
Commission decision exists that stops the import of meat from
Zimbabwe (Question 33).[2]
The remaining points are covered below.
DETAILS OF
THE NUMBER
OF INFECTED
PREMISES ON
WHICH FOOT
AND MOUTH
DISEASE WAS
CONFIRMED IN
THE SAMPLES
TAKEN FROM
THOSE PREMISES
(QUESTIONS 23
TO 28)
The information requested is as follows:
| Number of infected premises in Great Britain
| 2,026 |
| Number confirmed on clinical grounds | 1,851
|
| Number confirmed on laboratory results |
175 |
| Number confirmed clinically that were laboratory positive
| 1,156 |
| Number confirmed clinically that were laboratory negative
| 398 |
| Number confirmed clinically but not sampled
| 297 |
This means that of the 2,026 infected premises, there were
positive laboratory results in respect of 1,331 (66 per cent);
negative laboratory tests for 398 (20 per cent); and no samples
taken from the remaining 297 (15 per cent). (Percentages do not
add to 100 due to rounding).
It should be borne in mind that there are a number of reasons
why laboratory results may be negative but the infected premises
may still have disease. The Chief Veterinary Officer listed some
of these in his response to Question 27.
Two types of test are carried out; one looks for the presence
of virus and the other looks for antibodies which arise in response
to infection with FMD virus.
Depending on the species infected, the infectious dose of
virus that the animal receives and the route of infection, the
period of virus replication varies, therefore the period when
the virus may be detectable also varies. Virus may be detectable
in dairy cattle in milk up to four days before the first visible
lesion. In most circumstances virus is normally only excreted
for up to nine days following the first lesion but may it be as
short as six days or much longer. Detectable antibody starts to
develop three to five days after virus is first detectable in
the blood. Antibody is virus neutralising and therefore as the
antibody levels rise the virus excretion diminishes.
The richest source of virus is the epithelium of new or recently
ruptured vesicles. Virus taken from the lesions of animals may
not be detected or cultured in the lab for the following reasons
— The lesions may be old and no virus may be present
in the sample.
— Poor sampling technique may mean that the virus
is destroyed in the sample because of contamination with disinfectant
etc.
— Poor sample handling—for example being transported
exposed heat during transit, which kills the virus.
— Poor laboratory technique with a failure to culture
the virus.
Antibody tests (serology) may fail because the animals were
sampled before antibody has developed to detectable levels or
because a random sample of in-contact animals are sampled, the
wrong animals may be sampled.
Taking this into account, and given the difficulties of clinical
diagnosis of FMD in sheep, the policy of slaughter within 24 hours,
and the need to err on the side of caution in dealing with an
outbreak of this nature, the fact that 1,156 (74 per cent) of
the 1,554 clinically confirmed cases were laboratory positive
is not unexpected.
INFORMATION ON
THE NUMBER
OF ILLEGAL
MOVEMENTS THAT
TOOK PLACE
DURING THE
FOOT AND
MOUTH DISEASE
OUTBREAK (QUESTIONS
83 TO 84)
Illegal movements are by their nature covert, so comprehensive
information on the numbers of such movements is not available.
However, DEFRA receives regular reports from local authorities
on enforcement activity relating to the foot and mouth outbreak.
Information for the period up to 10 October indicates that there
have been 18 convictions obtained by local authorities across
Great Britain for offences involving the illegal movements of
animals. The courts have imposed penalties in the form of fines
of varying amounts on those responsible. These figures do not
include cases which have not yet reached a conclusion through
the courts, or where prosecutions were brought and no conviction
obtained, or which were dealt with by the local authority by means
other than prosecution, eg by formal or informal cautions for
which DEFRA does not have statistics.
Department for Environment, Food and Rural Affairs
9 November 2001
2
See Minutes of Evidence taken before the Environment, Food and
Rural Affairs Committee, The Animal Health Bill, 6 November 2001,
HC 339-i, Supplementary Memorandum. Back
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