EPIC Report
Summary
We have analysed Scottish sheep movement data to describe when and where sheep, from the isles of Lewis & Harris, are recorded as having moved to in 2021.
We have visually compared these movements with publicly available sheep scab notification data to give a preliminary indication of potential gaps in surveillance and a preliminary assessment of whether the impact of sheep scab control measures, if implemented in the isles of Lewis & Harris, could have a wider geographic effect on the occurrence of sheep scab in the Scottish sheep population.
We present the initial descriptive findings in this report, while we continue with further impact assessments and modelling.
Main points
Approximately 20,000 sheep are recorded as having moved off Lewis & Harris in 2021, in over 3,500 batches. The majority of all moves are non-slaughter moves i.e. to holdings other than slaughterhouses.
Just over a tenth of the sheep moved went to slaughterhouses in the last five months of the year (August to December). Almost all went to Stornoway without passing through a market.
Most sheep movement is to the agricultural region of Grampian (35%), with approximately 19% going to “Highland”, 15% across the Western Isles and 15% outside of Scotland.
These moves occur seasonally with more than 80% occurring in August and September.
The most popular markets used are Dingwall and Stornoway.
When maps of the frequency of sheep movements are placed alongside maps of sheep scab notification data, visually most sheep movements from Lewis & Harris are to the Highland, North and North-East of Scotland in the quarterly periods July to September and October to December. Meanwhile sheep scab notifications occur in the North and NE of Scotland in the period January to March.
It is possible that this observation is associated with infested animals being moved from Lewis & Harris at the end of the summer (Aug-Sept) into areas in the North and NE of Scotland, with the disease then manifesting in the autumn/winter, when we start to see increased scab notifications.
If that is the case, then sheep scab control measures implemented in Lewis & Harris could be expected to have an impact on the frequency of occurrence of sheep scab in these areas.
In addition, if the movement of infested animals from Lewis & Harris is a factor in the occurrence of sheep scab, and subsequent notification, in areas of Scotland receiving these sheep then there are apparent ‘gaps’ in the notification data i.e. an apparent lack of sheep scab notifications from Nairnshire, Moray and Banffshire, and Fife and Dumfries-shire.
Movements of sheep from Lewis & Harris are not the only reason that sheep scab may exist in the sheep in an area and there are multiple factors that may influence and lead to a notification of sheep scab being made, or not.
It should be noted that this is only a preliminary report; the analysis remains ‘in progress’. Up to date, more in-depth notifications data has been requested from the Animal and Plant Health Agency (APHA) to facilitate impact assessments and modelling.
It would be useful for the future impact assessments to discuss and identify with Lewis & Harris sheep keepers the types of sheep that are leaving, when and why, as this can not be determined from the sheep movements data.
The current and subsequent analyses will help to identify areas of the country that could be used (via serological screening) to determine the effect of the implementation of targeted control of scab on Lewis & Harris.
