Simulating disease in metapopulations of the
GB pig herd using real movement data
Daniel Franklin*1, Laura Green1, Graham Medley1
1School of Life Sciences, University of Warwick, Coventry, UK
*d.franklin@warwick.ac.uk
Objectives
Movement data
To simulate the spread of porcine
• 571876 movements over 2006 – 2008
reproductive & respiratory syndrome
• Each record has:
Movement data
Challenges
• Age of pigs moved not in
data
 Source and destination CPH and co-
(PRRS) and other diseases in GB pig
population.
• No data on populations of
ordinates
 Use movement data to find networks
farms
 Source and destination type (farm,
of farms
• Incomplete/Erroneous data
slaughterhouse… etc)
 Recreate demography of each farm
 Date
 To combine with disease simulation
 Number of pigs
PRRS
Demography
Networks
Stochastic disease simulation.
Simulated annealing is used to infer
Node 60
Node 61
Node 9
Node 59
the number and ages of pigs on the
Node 7
Node 11
Node 29
Node 4
Node 6
Node 10
Node 36
Node 38
Node 22
Node 15
Node 14
Node 19
Node 21
Node 56
Node 28
Node 55
farms.
Node 50
Node 54
Node 58
Node 40
Node 31
Node 8
Node 30
Node 33
Node 34
Node 37
Node 12
Node 42
Node 3
Node 13
Node 23
Node 18
Node 24
Node 20
Node 51
Node 52
Node 57
Node 39
Node 35
Node 32
Node 41
Node 2
Node 17
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300
NUMBER OF PIGS
Node 5
Node 27
Node 25
Node 49
250
Node 16
200
Node 46
150
Node 45
Node 47
100
Node 48
Node 44
50
Node 43
Node 1
0
50
45
40
35
30
25
WEEKS 20
15
IN YEAR
10
The red circle shows the ‘subject’ farm
5
0
0
5
10
15
20
AGE (WEEKS)
25
30
in this example. All those feeding into it
are the direct and indirect source farms
over a single year.
Combination & Next Steps
• PRRS, demography and networks will be brought together to create a simulation of the metapopulation and disease.
• Using real movement data within metapopulations.
• Each farm populated according to movement data and results of simulated annealing.
• Use model to draw conclusions on how network size and topology affects spread and persistence of PRRS and other
diseases.
• Code the simulations to account for control and intervention strategies, test for optimal solutions