Agriculture
Movements of itinerant contract sheep shearers / dippers in mainland Scotland.
FOOT AND MOUTH DISEASE
Veterinary Risk Assessment (No.8)
What are the current risks of causing new outbreaks of FMD, by allowing itinerant contract sheep shearers / dippers to operate between sheep farms in mainland Scotland?
Summary of the risk factors
Movements of personnel and equipment between farms during an FMD outbreak increases the risk of spreading infection to premises which were previously uninfected. The risk is that undisclosed infection will be carried to new locations. The important risk factors are:-
- There may be undisclosed FMD at farm premises (or at premises previously visited) because of "silent spread" of FMD by sheep, or the presence of susceptible livestock incubating disease. In 2001, sheep were the most significant "vectors" of FMD over long distances where disease went undetected.
- Subsequent mechanical spread of FMD virus - by people handling livestock (boots and clothing) and by vehicles/equipment used in connection with handling susceptible livestock.
The factors considered to be most responsible for increasing the risks are:-
- Movement of live animals onto farms delivered before the national movement ban came into force on 3 August 2007
- Poor disease detection in sheep not frequently inspected / poor awareness of appropriate biosecurity precautions on many farms throughout GB
Current position
The Scottish Executive published a Veterinary Risk Assessment on 10 August 2007 which recommended that Restriction Zone measures should be removed from the Scottish islands and sheep shearers and dippers can already freely operate on the islands. Most of the shearing in the south of Scotland is already completed, however some shearing remains to be done in the North of Scotland and autumn dipping is required to control ectoparasites. Restriction Zone measures remain on the mainland where contract shearing/dipping has remained suspended.
Summary of risk reducing factors
The possibility of undisclosed or incubating infection and its subsequent spread is mitigated by the following:
- Throughout the recent FMD outbreak in Surrey, there have been no reports of disease in Scotland and no cases of FMD have been confirmed in GB since 6 August.
- The incubation period for the strain of FMD virus causing the Surrey outbreak is thought to be between 5 and 8 days, although the incubation for FMD can be up to 14 days. There will have been 14 disease-free days in GB on 20 August.
- This strain of FMD in cattle and pigs has proved relatively straightforward to detect clinically and the general media interest in the FMD outbreak has raised farmer's awareness further.
- The latest epidemiology report on the outbreak of foot and mouth disease in Surrey, published on 15 August, concludes that the risk of disease spread outside of the Surrey Protection and Surveillance Zones is now considered to be very low.
- There are ongoing statutory controls to reduce the spread of undetected disease. including the pre-existing 6 day standstill periods applying to all farms in England and Wales and the 13 day standstill periods in Scotland, introduced after the 2001 FMD epidemic
- One of the most significant risk reduction measures has been the rapid introduction of the Restricted Zone measures, which prevented almost all movements of susceptible animals since the evening of Friday 3 August 2007.
- There have only been a limited number of animal movements from England and Wales to Scotland during the summer, as supported by preliminary modelling results and there are no reports on SAMU of any movements of sheep from Surrey into Scotland since 16 July 2007.
- Biosecurity standards can reasonably be expected to be higher as a result of the publicity generated by the current outbreak in Surrey.
- Although extensively kept sheep are not always closely or frequently inspected, extensively kept sheep are less likely to come into contact with, and propagate FMD virus.
It can be concluded that the current risk of undetected or incubating disease in susceptible livestock, including sheep, in mainland Scotland is now very low - defined by EFSA as "very rare if present, but cannot be excluded".
Because previously undetected/incubating disease cannot be ruled out, control measures are required to minimise further any risk of subsequent mechanical spread of FMD virus by contract shearers/dippers handling livestock (on boots and clothing) and by vehicles/equipment used in connection with shearing/dipping/handling sheep.
Risk Management
- Visits to shear/dip sheep may only be permitted under specific licence conditions.
- The frequency and exposure time between contract shearers and dippers and the sheep that they handle in different epidemiological groups, can be limited by restricting farm visits to one premises per day.
- Effective cleansing and disinfection of shearing/dipping personnel and equipment can be maximised by supervisory visits by SE Agriculture staff, to inspect all C&D processes on completion of the work at each location. Operators would need to apply in advance for specific licences and to inform SE Agriculture staff of their particular work schedules, to facilitate the required supervisory C&D visits.
- All livestock attendants must wear clean protective clothing that can be cleansed and disinfected in between visits to different locations on different days, or else wear new protective clothing on each occasion.
SUMMARY OF THE RECOMMENDED ACTION
Any risk of spreading FMD may be minimised further by restricting licences to cases where the shearing/dipping of sheep is considered essential for the wellbeing of those sheep at the current time.
The resumption of shearing/dipping should be considered, in the Restricted Zone, on the basis of the veterinary risk assessment and advice above.
Veterinary Division
Rural Directorate
Scottish Executive
20 August 2007