The Influence of Between-Farm Distance and Farm Size on the Spread of Classical Swine Fever during the 1997-1998 Epidemic in The Netherlands

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Abstract

As the size of livestock farms in The Netherlands is on the increase for economic reasons, an important question is how disease introduction risks and risks of onward transmission scale with farm size (i.e. with the number of animals on the farm). Here we use the epidemic data of the 1997–1998 epidemic of Classical Swine Fever (CSF) Virus in The Netherlands to address this question for CSF risks. This dataset is one of the most powerful ones statistically as in this epidemic a total of 428 pig farms where infected, with the majority of farm sizes ranging between 27 and 1750 pigs, including piglets. We have extended the earlier models for the transmission risk as a function of between-farm distance, by adding two factors. These factors describe the effect of farm size on the susceptibility of a ‘receiving’ farm and on the infectivity of a ‘sending’ farm (or ‘source’ farm), respectively. Using the best-fitting model, we show that the size of a farm has a significant influence on both farm-level susceptibility and infectivity for CSF. Although larger farms are both more susceptible to CSF and, when infected, more infectious to other farms than smaller farms, the increase is less than linear. The higher the farm size, the smaller the effect of increments of farm size on the susceptibility and infectivity of a farm. Because of changes in the Dutch pig farming characteristics, a straightforward extrapolation of the observed farm size dependencies from 1997/1998 to present times would not be justified. However, based on our results one may expect that also for the current pig farming characteristics in The Netherlands, farm susceptibility and infectivity depend non-linearly on farm size, with some saturation effect for relatively large farm sizes.
LanguageEnglish
Article numbere95278
Number of pages7
JournalPLoS ONE
Volume9
Issue number4
DOIs
Publication statusPublished - 2014

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Classical Swine Fever
hog cholera
farm size
Netherlands
Farms
farms
pathogenicity
large farms
swine
Swine
farming systems
Classical swine fever virus
small farms
Agriculture
piglets

Keywords

  • infectious-diseases
  • virus
  • transmission
  • strategies
  • model
  • risk

Cite this

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title = "The Influence of Between-Farm Distance and Farm Size on the Spread of Classical Swine Fever during the 1997-1998 Epidemic in The Netherlands",
abstract = "As the size of livestock farms in The Netherlands is on the increase for economic reasons, an important question is how disease introduction risks and risks of onward transmission scale with farm size (i.e. with the number of animals on the farm). Here we use the epidemic data of the 1997–1998 epidemic of Classical Swine Fever (CSF) Virus in The Netherlands to address this question for CSF risks. This dataset is one of the most powerful ones statistically as in this epidemic a total of 428 pig farms where infected, with the majority of farm sizes ranging between 27 and 1750 pigs, including piglets. We have extended the earlier models for the transmission risk as a function of between-farm distance, by adding two factors. These factors describe the effect of farm size on the susceptibility of a ‘receiving’ farm and on the infectivity of a ‘sending’ farm (or ‘source’ farm), respectively. Using the best-fitting model, we show that the size of a farm has a significant influence on both farm-level susceptibility and infectivity for CSF. Although larger farms are both more susceptible to CSF and, when infected, more infectious to other farms than smaller farms, the increase is less than linear. The higher the farm size, the smaller the effect of increments of farm size on the susceptibility and infectivity of a farm. Because of changes in the Dutch pig farming characteristics, a straightforward extrapolation of the observed farm size dependencies from 1997/1998 to present times would not be justified. However, based on our results one may expect that also for the current pig farming characteristics in The Netherlands, farm susceptibility and infectivity depend non-linearly on farm size, with some saturation effect for relatively large farm sizes.",
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author = "G.J. Boender and {van den Hengel}, R. and {van Roermund}, H.J.W. and T.H.J. Hagenaars",
year = "2014",
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The Influence of Between-Farm Distance and Farm Size on the Spread of Classical Swine Fever during the 1997-1998 Epidemic in The Netherlands. / Boender, G.J.; van den Hengel, R.; van Roermund, H.J.W.; Hagenaars, T.H.J.

In: PLoS ONE, Vol. 9, No. 4, e95278, 2014.

Research output: Contribution to journalArticleAcademicpeer-review

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T1 - The Influence of Between-Farm Distance and Farm Size on the Spread of Classical Swine Fever during the 1997-1998 Epidemic in The Netherlands

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AU - van den Hengel, R.

AU - van Roermund, H.J.W.

AU - Hagenaars, T.H.J.

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KW - risk

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