SPATIAL AND TEMPORAL ANALYSIS OF CATTLE MOVEMENTS … · 2015-11-13 · Characterization of such...
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Argentina´s cattle population is 52 million head (Senasa, 2104) which accounts for 70 percent of the animal production (Figure 1). The country is divided into 23 Provinces and one Autonomous District. Provinces are divided into Departments. In Argentina all movements of domestic livestock must be notified to the National Service for Agrifood Health and Quality (SENASA). More than 90 percent of the holdings are georeferenced and cattle identification is mandatory. Trade is one of the major transmission routes of infectious diseases and movement of live animals is one of the most important ways through which contagious diseases can spread among holdings (1). As a consequence, the evaluation of animal movement networks is of key importance for predicting and controlling the spread of infectious diseases. Characterization of such movements is important in order to establish areas and periods of high risk of introduction and potential spread of disease, as well as new measures to establish surveillance systems and identify farms at risk. This study aims at temporal-spatial characterization of cattle movements in Argentina in 2012. SPATIAL AND TEMPORAL ANALYSIS OF CATTLE MOVEMENTS IN ARGENTINA Linares, F.J.¹*; Rodriguez Vazquez, G.¹ ; Pérez, A.²; Cosentino, B.¹ ¹Directorate of Epidemiology and Risk Assessment. Directorate of Animal Health. National Service for Agrifood Health and Quality (SENASA). Argentina. ²Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota. United States of America. * [email protected] A detailed description of movements from holdings of origin and destination between Provinces and Departments was obtained from data supplied by SENASA Integrated Management System for Animal Health (SIGSA). This information includes frequency number of animals, types of movement, geographic coordinates, date of movement (day and month) and the National Register of Agricultural Producers (RENSPA). The description and analysis of movements and spatiotemporal patterns were performed using the methodology of network analysis algorithms and graph theory by R Language v2.10.1 with igraph library. The descriptive analysis was performed using graphs with Excel (12.0) and the maps were created by ArcGIS version 9.3 (ESRI) software. The distance of each movement was estimated through the Euclidean distance between the coordinates of each node. In 2012, a total of 1.1 million movements involving 27.4 million head of cattle were recorded in the SIGSA database (from holding to holding, from holding to animal market and from holding to slaughterhouse) (Table 1). When we analyzed holding to holding movements, concentrations of animals were found according to the season, more concentration in autumn (Figure 2). Similar results were observed in previous studies (2). Due to seasonality movements, surveillance could be targeted in different periods in the year. Movement distances were analyzed, the mean distance was 263 (3.5-1,547) kilometers. From the total number of cattle movements 75 percent traveled up to 391 km and 50 percent up to 210 kilometers (Figure 3). The results obtained in this study identified areas (Departments) and periods of high risk for the potential introduction and spread of cattle diseases in Argentina (Figure 4). This type of studies provides support to SENASA to design risk-based surveillance strategies and contingency plans. Moreover, this kind of methodology is particularly interesting in cattle diseases where animal movements are the primary means of disease introduction, and where movement databases are available and updated periodically, like in Argentina. It also offers essential information to include in computer models to simulate the potential disease spread and the potential epidemic size. From To Total of animals Total of movements Holding Holding 13,391,724 406,958 Holding Slaughterhouse 9,460,888 472,860 Holding Animal market 4,540,918 249,839 Table 1. Cattle movements in Argentina from holding to holding, holding to slaughterhouse and holding to animal market. Figure 1. Cattle density in Argentina SOURCE: Directorate of Epidemiology and Risk Assessment- SENASA. SOURCE: Directorate of Epidemiology and Risk Assessment- SENASA. (1)Kao, R.R. (2002). The role of mathematical modelling in the control of the 2001 FMD epidemic in the UK. Trends in Microbiology, 10, 279-286. (2)Aznar, M.N., Stevenson, M.A., Zarich, L., & León, E.A. (2011). Analysis of cattle movements in Argentina, 2005. Preventive Veterinary Medicine, 98, 119-127. 0 20.000 40.000 60.000 80.000 100.000 120.000 140.000 SUMMER AUTUMN WINTER SPRING NUMBER OF MOVEMENTS SEASON Figure 2. Movements from holding to holding by season SOURCE: Directorate of Epidemiology and Risk Assessment- SENASA. Figure 3. Number of movements from holding to holding. Distribution of movement according to distance (km) 0 2.000 4.000 6.000 8.000 10.000 12.000 14.000 16.000 18.000 DISTANCE (KIILOMETERS) NUMBER OF MOVEMENTS SOURCE: Directorate of Epidemiology and Risk Assessment- SENASA. ISVEE 14, MERIDA, YUCATAN, MEXICO, 3-7 NOVEMBER 2015 Mean 263 2 quartile (percentile 50) 210 3 quartile (percentile 75) 391 Min 3.5 Max 1,547 Standard deviation 196.5 OUTGOING MOVEMENTS OUTGOING ANIMALS OUTDEGREE OUTDEGREE OUTGOING MOVEMENTS OUTGOING ANIMALS OUTDEGREE OUTDEGREE INCOMING MOVEMENTS INCOMING ANIMALS INDEGREE INDEGREE INCOMING MOVEMENTS INCOMING ANIMALS INDEGREE INDEGREE SOURCE: Directorate of Epidemiology and Risk Assessment- SENASA. Figure 4. Holding to holding movements. Choropleth maps showing the spatial distribution of department-level in- and out-degree values. (a) Indegree; (b) Outdegree; (1) zone with vaccination; (2) zone without vaccination. 1.a) 2.a) 2.b) 1.b)
Transcript of SPATIAL AND TEMPORAL ANALYSIS OF CATTLE MOVEMENTS … · 2015-11-13 · Characterization of such...
Argentina´s cattle population is 52 million head (Senasa, 2104) which accounts for 70 percent of the animal production (Figure 1). The country is divided into 23 Provinces and one Autonomous District. Provinces are divided into Departments. In Argentina all movements of domestic livestock must be notified to the National Service for Agrifood Health and Quality (SENASA). More than 90 percent of the holdings are georeferenced and cattle identification is mandatory. Trade is one of the major transmission routes of infectious diseases and movement of live animals is one of the most important ways through which contagious diseases can spread among holdings (1). As a consequence, the evaluation of animal movement networks is of key importance for predicting and controlling the spread of infectious diseases. Characterization of such movements is important in order to establish areas and periods of high risk of introduction and potential spread of disease, as well as new measures to establish surveillance systems and identify farms at risk. This study aims at temporal-spatial characterization of cattle movements in Argentina in 2012.
SPATIAL AND TEMPORAL ANALYSIS OF CATTLE
MOVEMENTS IN ARGENTINA
Linares, F.J.¹*; Rodriguez Vazquez, G.¹ ; Pérez, A.²; Cosentino, B.¹
¹Directorate of Epidemiology and Risk Assessment. Directorate of Animal Health. National Service for Agrifood Health and Quality (SENASA). Argentina.
²Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota. United States of America. * [email protected]
A detailed description of movements from holdings of origin and destination between Provinces and Departments was obtained from data supplied by SENASA Integrated Management System for Animal Health (SIGSA). This information includes frequency number of animals, types of movement, geographic coordinates, date of movement (day and month) and the National Register of Agricultural Producers (RENSPA). The description and analysis of movements and spatiotemporal patterns were performed using the methodology of network analysis algorithms and graph theory by R Language v2.10.1 with igraph library. The descriptive analysis was performed using graphs with Excel (12.0) and the maps were created by ArcGIS version 9.3 (ESRI) software. The distance of each movement was estimated through the Euclidean distance between the coordinates of each node.
In 2012, a total of 1.1 million movements involving 27.4 million head of cattle were recorded in the SIGSA database (from holding to holding, from holding to animal market and from holding to slaughterhouse) (Table 1). When we analyzed holding to holding movements, concentrations of animals were found according to the season, more concentration in autumn (Figure 2). Similar results were observed in previous studies (2). Due to seasonality movements, surveillance could be targeted in different periods in the year. Movement distances were analyzed, the mean distance was 263 (3.5-1,547) kilometers. From the total number of cattle movements 75 percent traveled up to 391 km and 50 percent up to 210 kilometers (Figure 3). The results obtained in this study identified areas (Departments) and periods of high risk for the potential introduction and spread of cattle diseases in Argentina (Figure 4). This type of studies provides support to SENASA to design risk-based surveillance strategies and contingency plans. Moreover, this kind of methodology is particularly interesting in cattle diseases where animal movements are the primary means of disease introduction, and where movement databases are available and updated periodically, like in Argentina. It also offers essential information to include in computer models to simulate the potential disease spread and the potential epidemic size.
From To Total of
animals
Total of
movements
Holding Holding 13,391,724 406,958
Holding Slaughterhouse 9,460,888 472,860
Holding Animal market 4,540,918 249,839
Table 1. Cattle movements in Argentina from holding to holding, holding to slaughterhouse and
holding to animal market.
Figure 1. Cattle density in Argentina
SOURCE: Directorate of Epidemiology and Risk
Assessment- SENASA.
SOURCE: Directorate of Epidemiology and Risk Assessment- SENASA.
(1)Kao, R.R. (2002). The role of mathematical modelling in the control of the 2001 FMD epidemic in the UK. Trends in Microbiology, 10, 279-286. (2)Aznar, M.N., Stevenson, M.A., Zarich, L., & León, E.A. (2011). Analysis of cattle movements in Argentina, 2005. Preventive Veterinary Medicine, 98, 119-127.
0
20.000
40.000
60.000
80.000
100.000
120.000
140.000
SUMMER AUTUMN WINTER SPRING
NU
MB
ER
OF
MO
VE
ME
NT
S
SEASON
Figure 2. Movements from holding to holding by season
SOURCE: Directorate of Epidemiology and Risk Assessment- SENASA.
Figure 3. Number of movements from holding to holding. Distribution of movement according
to distance (km)
0
2.000
4.000
6.000
8.000
10.000
12.000
14.000
16.000
18.000
DISTANCE (KIILOMETERS)
NU
MB
ER
OF
MO
VE
ME
NT
S
SOURCE: Directorate of Epidemiology and Risk Assessment- SENASA.
ISVEE 14, MERIDA, YUCATAN, MEXICO, 3-7 NOVEMBER 2015
Mean 263
2 quartile (percentile 50) 210
3 quartile (percentile 75) 391
Min 3.5
Max 1,547
Standard deviation 196.5
OUTGOING MOVEMENTS OUTGOING ANIMALS
OUTDEGREE OUTDEGREE
OUTGOING MOVEMENTS OUTGOING ANIMALS
OUTDEGREE OUTDEGREE
INCOMING MOVEMENTS INCOMING ANIMALS
INDEGREE INDEGREE
INCOMING MOVEMENTS INCOMING ANIMALS
INDEGREE INDEGREE
SOURCE: Directorate of Epidemiology and Risk Assessment- SENASA.
Figure 4. Holding to holding movements. Choropleth maps showing the spatial distribution of department-level in- and out-degree values. (a) Indegree; (b) Outdegree; (1) zone with vaccination; (2) zone
without vaccination.
1.a) 2.a)
2.b) 1.b)
