FOOT AND MOUTH DISEASE
Veterinary Risk Assessment (No.4)
What is the risk of causing new outbreaks of FMD by removing the Restricted Zone measures from the Scottish Islands?
Summary of the risk factors
There is a hierarchy of risk of spreading FMD from an infected premises by the movement of livestock, their products and other mechanical means. In decreasing order these are:
- livestock
- livestock vehicles
- farm tractors and machinery
- other equipment used in connection with handling or other livestock related procedures, such as sheep shearing, dipping
- animal carcases and products
- farmers' and other livestock handlers' boots and clothing
Livestock
Livestock are the greatest risk because they actively excrete FMD virus. The incubation period for FMD can be up to 14 days but the incubation for the present strain causing the Surrey outbreak is thought to be between 5-8 days. All susceptible livestock excrete FMD virus in breath, saliva, milk, urine and faeces for up to 4 days before the appearance of clinical signs. Experience has shown that FMD in sheep is difficult to spot leading to a higher risk of sheep spreading infection.
Vehicles, tractors, machinery and other equipment
Vehicles, tractors, machinery and other equipment which have come from an infected farm can be heavily contaminated with FMD virus and can physically carry the infection elsewhere.
Itinerant contractors
Equipment used by sheep shearers, dippers and other contractors comes into close contact with livestock and can be difficult to cleanse and disinfect.
Carcases and products of fallen stock
The carcases of fallen stock or excreta from infected farms could carry FMD from an infected farm to another farm elsewhere. The virus is normally rapidly inactivated after death as the pH of the muscle falls. However, FMD virus can remain viable on the skin or hair of carcases for several days. (The carcases and other products from animals slaughtered at an abattoir are less likely to be contaminated because of the existing food hygiene controls).
Farmers and other livestock handlers
Farmers and other livestock handlers are a risk because of the likelihood that they will have had close contact with infected animals when visiting other farms. (Other non-agricultural visitors present a significantly lower risk).
The removal of the Restricted Zone controls from the Scottish Islands would increase the risk of spreading FMD within areas free from controls.
The factors considered to be most responsible for increasing the risk are:
- Movements of live animals on to farms delivered before the national movement ban came into force on 3 August. (This is the period of the so-called "silent spread" of FMD).
- Lack of awareness of appropriate biosecurity precautions on many farms throughout GB.
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Summary of risk reducing factors
There are many statutory controls which act to reduce risks. These include the pre-existing 6 day standstill periods applying to all farms in England & Wales and 13 day standstill periods in Scotland, introduced after the 2001 FMD epidemic. Pig premises are subject to different, more rigorous controls which restrict movements to within breeding pyramids and impose longer standstill period for movements which have taken place from outside the pyramid.
As soon as disease was suspected on the Surrey farm a TCZ of 1 km was imposed. Once FMD was confirmed controls on infected premises and on farms in the PZ and the SZ were implemented. One of the most significant risk reduction measures has been the rapid introduction of the Restricted Zone measures which have prevented almost all movements of susceptible animals since the evening of Friday 3 August 2007.
Epidemiological studies at the presumed source of the virus at Pirbright indicate 15 July as the earliest likely date of virus exposure.
There are existing laws requiring the movements of cattle to be notified to British Cattle Movement Service and the movements of sheep, goats and pigs to be reported to similar databases. These databases have been interrogated and these have shown:
- no movements of sheep from Surrey to Scotland since the beginning of July
- only 5 sheep have moved on to any Scottish Island since 15 July
o 2 from Ireland
o 3 from mainland Scotland
o 1 from Lancashire
- only 2 batches of pigs (one batch of 17, another of 8) have moved on islands from the mainland of GB - both from mainland Scotland
- no cattle have moved from England to any Scottish island since 15 July
- 7 batches of cattle (1,20,1,2,1,15,2) totalling 43 animals have moved from mainland Scotland to Scottish islands since 15 July
- the limited number of live animal movements from England and Wales to Scotland during the summer, supported by preliminary results from modelling
- fallen stock are not taken on to the Scottish islands for disposal
Other risk reducing factors include:
- many abattoirs across Scotland began operating on 9 August. All animals are inspected by the OV on arrival and all feet and mouths are being examined by meat inspectors.
- very few livestock vehicles moved anywhere in GB from the introduction of the RZ on 3 August until the general licence for the direct transport of animals to slaughter came into operation on 8 August. The conditions of the licence impose strict C&D requirements on vehicles and drivers.
- no carcases moved anywhere in GB from the introduction of the RZ on 3 August until the general licence for the removal of fallen stock came into operation on 8 August. The conditions of the licence impose strict C&D requirements on vehicles and drivers.
- certain agricultural service providers such as shearers, dipper, foot-parers, ultra-sound scanners and freeze branders have not been operating since 3 August.
- the general media interest in the FMD outbreak has raised farmers' awareness that FMD is in GB.
- biosecurity standards generally may be higher.
Consideration of the above summary of risk reducing factors suggests that no live animal movements on to the islands have occurred during the risk period and that RZ controls since 3 August have significantly reduced the spread by other means.
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The level of risk and possible consequences
The OIE classifies risks as being:
High
Medium
Low
Negligible
The level of risk of FMD occurring somewhere in GB is never negligible even in periods between active epidemics. However this qualitative veterinary risk assessment has demonstrated that there is likely to be very little increase in the risk of FMD occurring in the Scottish islands compared to inter-epidemic periods.
The consequences of the disease occurring on a Scottish island and spreading to the mainland of GB are very grave. The consequences of an outbreak on a Scottish island which did not spread to other parts of Scotland would be very serious but could be contained.
Therefore the low but not negligible risk of FMD occurring on a Scottish island must be accompanied by measures to minimise the risk of an outbreak spreading to the mainland of Scotland. These must take account of the distance and time of transport from the mainland of Scotland and other islands.
Risk management options
(1) Restriction Zone measures could be lifted from islands with the pre-condition that there can be no movements between the islands or to the Scottish mainland other than those currently permitted in the RZ.
(2) Restriction Zone measures could be lifted from islands with the pre-condition that there can only be movements between the islands joined by bridges or causeways but no movements to other islands or to the Scottish mainland other than those currently permitted in the RZ.
(3) Restriction Zone measures could be lifted from islands with the pre-condition that there can only be movements between islands within certain defined groups, for example local authority areas, but there can be no movements to islands outside the defined grouping or to the Scottish mainland other than those currently permitted in the RZ.
(4) Restriction Zone measures could be lifted from islands with the pre-condition that there can only be movements between islands within a larger number of defined groups but there can be no movements to islands outside the defined grouping or to the Scottish mainland other than those currently permitted in the RZ.
(5) Restriction Zone measures could be lifted from islands with the pre-condition that there can be free movements between the islands but not to the Scottish mainland other than those currently permitted in the RZ.
Discussion of the risk management options
(1) Single island freedom - the most risk adverse solution but would not relieve many of the difficulties caused by the present RZ rules.
(2) Islands with bridges freedom - this would allow many activities to return to normal but would not relieve some of the pressing husbandry and welfare problems
(3) Island grouping by local authority - this would allow many activities to return to normal over many of the most animal-densely populated islands relieve most of the pressing husbandry and welfare problems
(4) All islands grouping - this would not allow significantly more animals to move than option (3) above and would be confusing to farmers and impossible to enforce
(5) Island free-for-all - the majority of transport links are between groups of islands and the mainland of Scotland so this option provides little more relief from the RZ measures.
SUMMARY OF THE RECOMMENDED ACTION
Option (3) offers the most practical solution. The RZ measures should be removed from all the islands but free movement must only be permitted within the island groupings of Orkney, Shetland and the Western Isles. All other islands are free from RZ measures but there can be no movements to islands outside the defined grouping or to the Scottish mainland other than those currently permitted in the RZ.
The current provisions of the measures described in Schedule 6, paragraph 8(1) must remain in place to prevent contractors moving from the mainland of GB to work on the Scottish islands.
All livestock keepers in the Scottish islands should be reminded of their important responsibility to conduct their businesses in accordance with the good practice guidance outlined in the Scottish Biosecurity Code.
Veterinary Division
Rural Directorate
Scottish Executive
10 August 2007
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