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 ...
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.