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Where's the risk? Landscape epidemiology of gastrointestinal parasitism in Alberta beef cattle.

Beck MA, Colwell DD, Goater CP, Kienzle SW - Parasit Vectors (2015)

Bottom Line: Using a GIS and Bayesian multivariate spatial statistics, we evaluated the degree to which variation in specific environmental covariates (e.g. moisture, humidity, temperature) was associated with variation in spatial and temporal heterogeneity in exposure to GIN (Nematodirus and other trichostrongyles, primarily Ostertagia and Cooperia).Variation in growing degree days above a base temperature of 5 °C, humidity, air temperature, and accumulated precipitation were found to be significant predictors of broad-scale spatial and temporal variation in serum antibody concentrations.Although more targeted sampling is needed to improve model accuracy, our projections represent an important step towards tying treatment recommendations to actual risk of infection.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, University of Lethbridge, 4401 University Drive, Lethbridge, AB, T1K 3 M4, Canada. m.beck@uleth.ca.

ABSTRACT

Background: Gastrointenstinal nematodes (GIN) present a serious challenge to the health and productivity of grazing stock around the globe. However, the epidemiology of GIN transmission remains poorly understood in northern climates. Combining use of serological diagnostics, GIS mapping technology, and geospatial statistics, we evaluated ecological covariates of spatial and temporal variability in GIN transmission among bovine calves pastured in Alberta, Canada.

Methods: Sera were collected from 1000 beef calves across Alberta, Canada over three consecutive years (2008-2010) and analyzed for presence of anti-GIN antibodies using the SVANOVIR Ostertagia osteragi-Ab ELISA kit. Using a GIS and Bayesian multivariate spatial statistics, we evaluated the degree to which variation in specific environmental covariates (e.g. moisture, humidity, temperature) was associated with variation in spatial and temporal heterogeneity in exposure to GIN (Nematodirus and other trichostrongyles, primarily Ostertagia and Cooperia).

Results: Variation in growing degree days above a base temperature of 5 °C, humidity, air temperature, and accumulated precipitation were found to be significant predictors of broad-scale spatial and temporal variation in serum antibody concentrations. Risk model projections identified that while transmission in cattle from southeastern and northwestern Alberta was relatively low in all years, rate of GIN transmission was generally higher in the central region of Alberta.

Conclusions: The spatial variability in risk is attributed to higher average humidity, precipitation and moderate temperatures in the central region of Alberta in comparison with the hot, dry southeastern corner of the province and the cool, dry northwestern corner. Although more targeted sampling is needed to improve model accuracy, our projections represent an important step towards tying treatment recommendations to actual risk of infection.

No MeSH data available.


Related in: MedlinePlus

Sampling polygons for GIN survey in southern Alberta bovine calves. Southern Alberta was delineated into 26 service area polygons based on analyses of minimum driving distance to auction markets in accordance with the existing road network.
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Fig1: Sampling polygons for GIN survey in southern Alberta bovine calves. Southern Alberta was delineated into 26 service area polygons based on analyses of minimum driving distance to auction markets in accordance with the existing road network.

Mentions: The province of Alberta extends from 49 to 60° latitude north, with an area of approximately 661,848 square km. The province has three major biogeographical divisions ranging from west to east which vary in elevation and associated climate: the mountains, the foothills, and the plains [19]. Our study area is focused on the 79, 000 square km plains region where grazing on native rangelands and Crown and community pastures is most extensive (Fig. 1) [19]. The plains region comprises the majority of the total area of the province, with elevation varying from 800 m along the eastern border of the province to approximately 1800 m along the foothills belt in the west [20]. The southeastern corner of this region has an average annual precipitation (1971–2000) of 331 mm (CV: 8.4 %), and an annual maximum temperature (1971–2000) of 21.7 °C (CV: 0.3 %) during peak grazing season (Jun to Oct) that is associated with a high rate of evapotranspiration, frequent hot dry winds, and prolonged periods of low precipitation. Further north, the annual precipitation increases to about 515 mm (CV: 7 %) in the centre of this zone, and then decreases to 475 mm (CV: 6.0 %) in the far northwest and 487 mm (CV: 13.0 %) in the northeast. Evapotranspiration likely decreases with a maximum annual temperature of 16.8 °C (CV: 0.2 %) during the grazing season in the northwest of this region and 18 °C (CV: 0.2 %) in the northeast. Average precipitation also increases markedly from east to west, with approximately 368 mm (CV: 7.7 %) of rain along the eastern boarder of the province to as much as 467 mm (CV: 8.5 %) on the edge of the foothills [21].Fig. 1


Where's the risk? Landscape epidemiology of gastrointestinal parasitism in Alberta beef cattle.

Beck MA, Colwell DD, Goater CP, Kienzle SW - Parasit Vectors (2015)

Sampling polygons for GIN survey in southern Alberta bovine calves. Southern Alberta was delineated into 26 service area polygons based on analyses of minimum driving distance to auction markets in accordance with the existing road network.
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4548846&req=5

Fig1: Sampling polygons for GIN survey in southern Alberta bovine calves. Southern Alberta was delineated into 26 service area polygons based on analyses of minimum driving distance to auction markets in accordance with the existing road network.
Mentions: The province of Alberta extends from 49 to 60° latitude north, with an area of approximately 661,848 square km. The province has three major biogeographical divisions ranging from west to east which vary in elevation and associated climate: the mountains, the foothills, and the plains [19]. Our study area is focused on the 79, 000 square km plains region where grazing on native rangelands and Crown and community pastures is most extensive (Fig. 1) [19]. The plains region comprises the majority of the total area of the province, with elevation varying from 800 m along the eastern border of the province to approximately 1800 m along the foothills belt in the west [20]. The southeastern corner of this region has an average annual precipitation (1971–2000) of 331 mm (CV: 8.4 %), and an annual maximum temperature (1971–2000) of 21.7 °C (CV: 0.3 %) during peak grazing season (Jun to Oct) that is associated with a high rate of evapotranspiration, frequent hot dry winds, and prolonged periods of low precipitation. Further north, the annual precipitation increases to about 515 mm (CV: 7 %) in the centre of this zone, and then decreases to 475 mm (CV: 6.0 %) in the far northwest and 487 mm (CV: 13.0 %) in the northeast. Evapotranspiration likely decreases with a maximum annual temperature of 16.8 °C (CV: 0.2 %) during the grazing season in the northwest of this region and 18 °C (CV: 0.2 %) in the northeast. Average precipitation also increases markedly from east to west, with approximately 368 mm (CV: 7.7 %) of rain along the eastern boarder of the province to as much as 467 mm (CV: 8.5 %) on the edge of the foothills [21].Fig. 1

Bottom Line: Using a GIS and Bayesian multivariate spatial statistics, we evaluated the degree to which variation in specific environmental covariates (e.g. moisture, humidity, temperature) was associated with variation in spatial and temporal heterogeneity in exposure to GIN (Nematodirus and other trichostrongyles, primarily Ostertagia and Cooperia).Variation in growing degree days above a base temperature of 5 °C, humidity, air temperature, and accumulated precipitation were found to be significant predictors of broad-scale spatial and temporal variation in serum antibody concentrations.Although more targeted sampling is needed to improve model accuracy, our projections represent an important step towards tying treatment recommendations to actual risk of infection.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, University of Lethbridge, 4401 University Drive, Lethbridge, AB, T1K 3 M4, Canada. m.beck@uleth.ca.

ABSTRACT

Background: Gastrointenstinal nematodes (GIN) present a serious challenge to the health and productivity of grazing stock around the globe. However, the epidemiology of GIN transmission remains poorly understood in northern climates. Combining use of serological diagnostics, GIS mapping technology, and geospatial statistics, we evaluated ecological covariates of spatial and temporal variability in GIN transmission among bovine calves pastured in Alberta, Canada.

Methods: Sera were collected from 1000 beef calves across Alberta, Canada over three consecutive years (2008-2010) and analyzed for presence of anti-GIN antibodies using the SVANOVIR Ostertagia osteragi-Ab ELISA kit. Using a GIS and Bayesian multivariate spatial statistics, we evaluated the degree to which variation in specific environmental covariates (e.g. moisture, humidity, temperature) was associated with variation in spatial and temporal heterogeneity in exposure to GIN (Nematodirus and other trichostrongyles, primarily Ostertagia and Cooperia).

Results: Variation in growing degree days above a base temperature of 5 °C, humidity, air temperature, and accumulated precipitation were found to be significant predictors of broad-scale spatial and temporal variation in serum antibody concentrations. Risk model projections identified that while transmission in cattle from southeastern and northwestern Alberta was relatively low in all years, rate of GIN transmission was generally higher in the central region of Alberta.

Conclusions: The spatial variability in risk is attributed to higher average humidity, precipitation and moderate temperatures in the central region of Alberta in comparison with the hot, dry southeastern corner of the province and the cool, dry northwestern corner. Although more targeted sampling is needed to improve model accuracy, our projections represent an important step towards tying treatment recommendations to actual risk of infection.

No MeSH data available.


Related in: MedlinePlus