Prevalence and distribution of lice on sheep and cattle farms in Great Britain

Network analyses can assist in predicting the course of epidemics. Time-directed paths or ‘contact chains' provide a measure of host-connectedness 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 disseminating infections.

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Distribution and prevalence of ticks and tick-borne disease on sheep and cattle farms in Great Britain

Parasites & Vectors ◽

10.1186/s13071-020-04287-9 ◽

2020 ◽

Vol 13 (1) ◽

Author(s):

Katie Lihou ◽

Hannah Rose Vineer ◽

Richard Wall

Keyword(s):

Great Britain ◽

Tick Borne Disease ◽

Cattle Farms

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Effects of trading networks on the risk of bovine tuberculosis incidents on cattle farms in Great Britain

Royal Society Open Science ◽

10.1098/rsos.191806 ◽

2020 ◽

Vol 7 (4) ◽

pp. 191806

Author(s):

Helen R. Fielding ◽

Trevelyan J. McKinley ◽

Richard J. Delahay ◽

Matthew J. Silk ◽

Robbie A. McDonald

Keyword(s):

Great Britain ◽

Bovine Tuberculosis ◽

Disease Risk ◽

Herd Size ◽

Risk Area ◽

High Risk Area ◽

Trading Patterns ◽

Additional Approach ◽

Trading Networks ◽

Cattle Farms

Trading animals between farms and via markets can provide a conduit for spread of infections. By studying trading networks, we might better understand the dynamics of livestock diseases. We constructed ingoing contact chains of cattle farms in Great Britain that were linked by trading, to elucidate potential pathways for the transmission of infection and to evaluate their effect on the risk of a farm experiencing a bovine tuberculosis (bTB) incident. Our findings are consistent with variation in bTB risk associated with region, herd size, disease risk area and history of previous bTB incidents on the root farm and nearby farms. However, we also identified effects of both direct and indirect trading patterns, such that connections to more farms in the England High-Risk Area up to three movements away from the root farm increased the odds of a bTB incident, while connections with more farms in the England Low-Risk Area up to eight movements away decreased the odds. Relative to other risk factors for bTB, trading behaviours are arguably more amenable to change, and consideration of risks associated with indirect trading, as well direct trading, might therefore offer an additional approach to bTB control in Great Britain.

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