Theoretical modelling can predict spread of infection over a given area
for defined weather parameters, illustrated in this sequence of diagrams.
A continuous 7 day weather pattern was used in the programme to calculate
the spread each day over a radius of 10 km from a notional point source
of, initially, one infected pig excreting virus as an aerosol. On day
4 in this example the number of excreting animals increases to three
by the addition of two cows developing disease on the source farm. Note
that virus spread is very localised on any particular day, and the final
plot is a summation of likely disease spread after one week. If the
relevant map of the area is overlayed with this plot then the location
of other susceptible farms and animals can be identified.
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Day 1
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Day 2
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Day 3
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Day 4
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Day 5
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Day 6
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Day 7
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All days
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