This is the final version. Available from the publisher via the DOI in this record.Further information and figures supporting this article have been uploaded as part of the electronic
supplementary material. Underlying data consist of every movement of cattle between all farms in Great Britain.
Aside from the size of the dataset, there are substantial issues of confidentiality (locations, trading practices) and
commercial sensitivity in these data. They are collated and managed by Defra, via the Animal and Plant Health
Agency, who grant access to the data with specific permissions for specific studies. In practice, this means that the
data can be used for the stated purpose only, and making the data publicly accessible would not conform to the
licence the authors have been granted to use these data. With the agreement of the journal’s Editorial Office, the
authors will not be able to make the dataset available on this occasion, but encourage readers, referees and editors
to contact the Animal and Plant Health Agency data manager for data access requests. At the time of submission,
the data manager is Andy Mitchell ([email protected])Network analyses can assist in predicting the course of epidemics.
Time-directed paths or ‘contact chains’ provide a measure of hostconnectedness across specified timeframes, and so represent
potential pathways for spread of infections with different
epidemiological characteristics. We analysed networks and
contact chains of cattle farms in Great Britain using Cattle
Tracing System data from 2001 to 2015. We focused on the
potential for between-farm transmission of bovine tuberculosis,
a chronic infection with potential for hidden spread through
the network. Networks were characterized by scale-free type
properties, where individual farms were found to be influential
‘hubs’ in the network. We found a markedly bimodal
distribution of farms with either small or very large ingoing and
outgoing contact chains (ICCs and OCCs). As a result of their
cattle purchases within 12-month periods, 47% of British farms
were connected by ICCs to more than 1000 other farms and 16%
were connected to more than 10 000 other farms. As a result of
their cattle sales within 12-month periods, 66% of farms had
OCCs that reached more than 1000 other farms and 15% reached
more than 10 000 other farms. Over 19 000 farms had both ICCs
and OCCs reaching more than 10 000 farms for two or more
years. While farms with more contacts in their ICCs or OCCs
might play an important role in disease spread, farms with
extensive ICCs and OCCs might be particularly important by
being at higher risk of both acquiring and disseminatinginfections.Biotechnology and Biological Science Research Council (BBSRC
