Limits...
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

Model predicted spatial and temporal variation in risk of GIN transmission in Alberta bovine calves (2008–2010). Distribution of expected risk of nematode transmission calculated for each year using Bayesian inference to construct hierarchical binary response logistic regression models for ODR in cattle sampled at auction markets in southern Alberta from 2008 to 2010. Low, Moderate and High risk are differentiated according to mean regional optical density ratio values of <0.3, 0.3-0.5, and >0.5 respectively for cattle serum
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig3: Model predicted spatial and temporal variation in risk of GIN transmission in Alberta bovine calves (2008–2010). Distribution of expected risk of nematode transmission calculated for each year using Bayesian inference to construct hierarchical binary response logistic regression models for ODR in cattle sampled at auction markets in southern Alberta from 2008 to 2010. Low, Moderate and High risk are differentiated according to mean regional optical density ratio values of <0.3, 0.3-0.5, and >0.5 respectively for cattle serum

Mentions: Expected ODR was calculated for each of the 4 models (Table 2), averaged to account for model uncertainty [35] and projected across the study area for all three years (Fig. 3). Model projected risk was consistently low (ODR <0.35) in the far southeast. The total area where risk of economically significant infection was high increased in 2010 in comparison with 2008. This change may be attributed to a general increase in accumulated precipitation, fewer total GDDs, lower average maximum temperature, and higher minimum average temperature (Table 3). In comparison, total number of GDD was notably higher in these same polygons in 2009, with maximum temperature ranges similar to that of 2008.Table 2


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

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

Model predicted spatial and temporal variation in risk of GIN transmission in Alberta bovine calves (2008–2010). Distribution of expected risk of nematode transmission calculated for each year using Bayesian inference to construct hierarchical binary response logistic regression models for ODR in cattle sampled at auction markets in southern Alberta from 2008 to 2010. Low, Moderate and High risk are differentiated according to mean regional optical density ratio values of <0.3, 0.3-0.5, and >0.5 respectively for cattle serum
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig3: Model predicted spatial and temporal variation in risk of GIN transmission in Alberta bovine calves (2008–2010). Distribution of expected risk of nematode transmission calculated for each year using Bayesian inference to construct hierarchical binary response logistic regression models for ODR in cattle sampled at auction markets in southern Alberta from 2008 to 2010. Low, Moderate and High risk are differentiated according to mean regional optical density ratio values of <0.3, 0.3-0.5, and >0.5 respectively for cattle serum
Mentions: Expected ODR was calculated for each of the 4 models (Table 2), averaged to account for model uncertainty [35] and projected across the study area for all three years (Fig. 3). Model projected risk was consistently low (ODR <0.35) in the far southeast. The total area where risk of economically significant infection was high increased in 2010 in comparison with 2008. This change may be attributed to a general increase in accumulated precipitation, fewer total GDDs, lower average maximum temperature, and higher minimum average temperature (Table 3). In comparison, total number of GDD was notably higher in these same polygons in 2009, with maximum temperature ranges similar to that of 2008.Table 2

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