Spatial and temporal investigations of reported movements, births and deaths of cattle and pigs in Sweden

Abstract

Background: Livestock movements can affect the spread and control of contagious diseases and new data recording systems enable analysis of these movements. The results can be used for contingency planning, modelling of disease spread and design of disease control programs.

Methods: Data on the Swedish cattle and pig populations during the period July 2005 until June 2006 were obtained from databases held by the Swedish Board of Agriculture. Movements of cattle and pigs were investigated from geographical and temporal perspectives, births and deaths of cattle were investigated from a temporal perspective and the geographical distribution of holdings was also investigated.

Results: Most movements of cattle and pigs were to holdings within 100 km, but movements up to 1200 km occurred. Consequently, the majority of movements occurred within the same county or to adjacent counties. Approximately 54% of the cattle holdings and 45% of the pig holdings did not purchase any live animals. Seasonal variations in births and deaths of cattle were identified, with peaks in spring. Cattle movements peaked in spring and autumn. The maximum number of holdings within a 3 km radius of one holding was 45 for cattle and 23 for pigs, with large variations among counties. Missing data and reporting bias (digit preference) were detected in the data.

Conclusion: The databases are valuable tools in contact tracing. However since movements can be reported up to a week after the event and some data are missing they cannot replace other methods in the acute phase of an outbreak. We identified long distance transports of cattle and pigs, and these findings support an implementation of a total standstill in the country in the case of an outbreak of foot-and-mouth disease. The databases contain valuable information and improvements in data quality would make them even more useful.

Figure 1

Cattle holdings in Sweden. Map over Sweden showing active, registered cattle holdings. © Lantmäteriet Gävle 2009. Medgivande I 2009/0830.

Figure 2

Pig holdings in Sweden. Map over Sweden showing active, registered pig holdings. © Lantmäteriet Gävle 2009. Medgivande I 2009/0830.

Figure 3

Reported movements of cattle, by distance. Movements of Swedish cattle during the period between July 1^st 2005 and June 30^th 2006 by distance between the holding of origin and the holding of destination. All animals transported between the same two holdings on the same date were regarded as one movement, movements of cattle to pasture are not included.

Figure 4

Reported movements of pigs, by distance. Movements of Swedish pigs during the period between July 1^st 2005 and June 30^th 2006 by distance between the holding of origin and the holding of destination. All animals transported between the same two holdings on the same date were regarded as one movement.

Figure 5

Reported movements of cattle and pigs, seasonal variation. Number of reported movements of Swedish cattle and pigs from one holding to another per week during the period between July 1^st 2005 and June 30^th 2006. All animals transported between the same two holdings on the same date were regarded as one movement. (The first week included only 5 days, and the last week only two days and therefore not shown in the graph.)

Figure 6

Reported movements of cattle and pigs per day of the week. Mean numbers of reported movements of Swedish cattle and pigs from one holding to another per day of the week (national holidays were treated as Sundays) during the period between July 1^st 2005 and June 30^th 2006. All animals transported between the same two holdings on the same date were regarded as one movement.

Figure 7

Trade between holdings, cattle. Trade between Swedish cattle holdings during the period between July 1^st 2005 and June 30^th 2006, shown by the number of holdings that cattle have been sold to or purchased from. There were 15502 cattle holdings that did not sell cattle and 16366 that did not purchase cattle during the period. There were 47 holdings that sold to more than 20 holdings and 252 that bought from more than 20 holdings.

Figure 8

Trade between holdings, pigs. Trade between Swedish pig holdings during the period between July 1^st 2005 and June 30^th 2006, shown by the number of holdings that pigs have been sold to or purchased from. There were 1787 pig holdings that did not sell pigs and 1421 that did not purchase pigs during the period. There were 63 holdings that sold to more than 20 holdings and 115 that bought from more than 20 holdings.

Figure 9

Cattle holdings within 3 and 10 km. Number of registered, active cattle holdings within 3 and 10 km radius from each cattle holding, in Sweden, Norrbotten and Skåne.

Figure 10

Pig holdings within 3 and 10 km radius. Number of registered, active pig holdings within 3 and 10 km radius from each pig holding, in Sweden, Norrbotten and Skåne.

Figure 11

Reported births and deaths, seasonal variation. Number of reported births and deaths of Swedish cattle per week during the period between July 1^st 2005 and June 30^th 2006.

Figure 12

Reported deaths per day of the week. Mean numbers of reported deaths of Swedish cattle per day of the week, during the period between July 1^st 2005 and June 30^th 2006.

Figure 13

Reported births per day of the week. Mean numbers of reported births of Swedish cattle per day of the week, during the period between July 1^st 2005 and June 30^th 2006.

Figure 14

Reported deaths per day of the month. Mean numbers of reported deaths of Swedish cattle per day of the month, during the period between July 1^st 2005 and June 30^th 2006.

Figure 15

Reported births per day of the month. Mean numbers of reported births of Swedish cattle per day of the month, during the period between July 1^st 2005 and June 30^th 2006.