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Free keywords:
SIR epidemic model; directed network; animal movements; network analysis; control measures
Abstract:
This study considered a simple SIR model for the spread of epidemics amongst
holdings of a producer community in Northern Germany, based on the directed
network of animal movements. The aim of this study was to evaluate the efficiency
of different control measures to reduce the epidemic size substantially. The
currently applied control measures based on the distance to an infected holding
were compared with the control measures based on the specific network-based
centrality parameters. We found that network-based measures led to a more efficient
control of epidemics with a much smaller number of removed holdings. To
assess the impact of different holding types, the analysed control measures were
implemented by both including and excluding these holding types. The comparison
revealed a crucial role of multipliers in the spread of an epidemic. The network-
based control measures depending on the removal by out-degree, outgoing
infection chain, betweenness centrality and outgoing closeness centrality showed
the best results: In the three-year network, on average, 2.75, 4.15, 3.73 and 3.43
times more holdings had to be removed by the control measures based on the 1,
3, 5 and 10 km radius to reduce the epidemic to the same size compared with the
network-based control measures. In an area with a higher holding density, the
improvement of the network-based control measures may become even more
obvious. The removal of holdings based on the above-mentioned centrality
parameters did thus not only rapidly decompose the network into fragments, but
also reduced the epidemic size most efficiently.
