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Q fever infection in dairy cattle herds: increased risk with high wind speed and low precipitation.

Nusinovici S, Frössling J, Widgren S, Beaudeau F, Lindberg A - Epidemiol. Infect. (2015)

Bottom Line: The implementation of effective control measures against Cb in ruminants requires knowledge about potential risk factors.The prevalence of test-positive herds was higher in the south of Sweden.Finally, the cumulated precipitation over 1 year was identified as a protective factor.

View Article: PubMed Central - PubMed

Affiliation: INRA,UMR1300 Biology,Epidemiology and Risk Analysis in Animal Health,CS 40706,F-44307 Nantes,France.

ABSTRACT
Ruminants are considered the main reservoir for transmission of Coxiella burnetii (Cb) to humans. The implementation of effective control measures against Cb in ruminants requires knowledge about potential risk factors. The objectives of this study were (i) to describe the spatial distribution of Q fever-infected dairy cattle herds in Sweden, (ii) to quantify the respective contributions of wind and animal movements on the risk of infection, while accounting for other sources of variation, and (iii) to investigate the possible protective effect of precipitation. A total of 1537 bulk milk samples were collected and tested for presence of Cb antibodies. The prevalence of test-positive herds was higher in the south of Sweden. For herds located in areas with high wind speed, open landscape, high animal densities and high temperature, the risk of being infected reached very high values. Because these factors are difficult to control, vaccination could be an appropriate control measure in these areas. Finally, the cumulated precipitation over 1 year was identified as a protective factor.

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(a) Principal component analysis (PCA). This analysis was performed on the following variables: result of the ELISA test against Coxiella burnetii (ELISA 0/1), wind speed, cumulated precipitation, percentage of open landscape (Landscape), animal movements (In-degree), cattle and sheep densities and temperature. (b) Hierarchical clustering performed on the first two components of the PCA [using the five correlated variables wind speed, percent of open landscape, animal densities (cattle and sheep) and temperature]. In all, 1537 Swedish dairy herds tested in 2008–2009 were included in this study on risk factors for C. burnetii infection.
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fig02: (a) Principal component analysis (PCA). This analysis was performed on the following variables: result of the ELISA test against Coxiella burnetii (ELISA 0/1), wind speed, cumulated precipitation, percentage of open landscape (Landscape), animal movements (In-degree), cattle and sheep densities and temperature. (b) Hierarchical clustering performed on the first two components of the PCA [using the five correlated variables wind speed, percent of open landscape, animal densities (cattle and sheep) and temperature]. In all, 1537 Swedish dairy herds tested in 2008–2009 were included in this study on risk factors for C. burnetii infection.

Mentions: Wind data, percent of open landscape, animal densities (cattle and sheep) and temperature were strongly correlated (Figs 1 and 2a). To avoid multicollinearity issues while still keeping the information contained in these variables, it was decided to aggregate them into a single variable to be used in the multivariable model. To do so, a principal component analysis (PCA) was performed using the correlated variables, as proposed by Dohoo et al. [29], and then a hierarchical clustering was performed on the first two components of the PCA (Fig. 2b). This method allows the identification of different groups based on the distance between herds in the two-dimensional PCA projections [30].Fig. 1.


Q fever infection in dairy cattle herds: increased risk with high wind speed and low precipitation.

Nusinovici S, Frössling J, Widgren S, Beaudeau F, Lindberg A - Epidemiol. Infect. (2015)

(a) Principal component analysis (PCA). This analysis was performed on the following variables: result of the ELISA test against Coxiella burnetii (ELISA 0/1), wind speed, cumulated precipitation, percentage of open landscape (Landscape), animal movements (In-degree), cattle and sheep densities and temperature. (b) Hierarchical clustering performed on the first two components of the PCA [using the five correlated variables wind speed, percent of open landscape, animal densities (cattle and sheep) and temperature]. In all, 1537 Swedish dairy herds tested in 2008–2009 were included in this study on risk factors for C. burnetii infection.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4594051&req=5

fig02: (a) Principal component analysis (PCA). This analysis was performed on the following variables: result of the ELISA test against Coxiella burnetii (ELISA 0/1), wind speed, cumulated precipitation, percentage of open landscape (Landscape), animal movements (In-degree), cattle and sheep densities and temperature. (b) Hierarchical clustering performed on the first two components of the PCA [using the five correlated variables wind speed, percent of open landscape, animal densities (cattle and sheep) and temperature]. In all, 1537 Swedish dairy herds tested in 2008–2009 were included in this study on risk factors for C. burnetii infection.
Mentions: Wind data, percent of open landscape, animal densities (cattle and sheep) and temperature were strongly correlated (Figs 1 and 2a). To avoid multicollinearity issues while still keeping the information contained in these variables, it was decided to aggregate them into a single variable to be used in the multivariable model. To do so, a principal component analysis (PCA) was performed using the correlated variables, as proposed by Dohoo et al. [29], and then a hierarchical clustering was performed on the first two components of the PCA (Fig. 2b). This method allows the identification of different groups based on the distance between herds in the two-dimensional PCA projections [30].Fig. 1.

Bottom Line: The implementation of effective control measures against Cb in ruminants requires knowledge about potential risk factors.The prevalence of test-positive herds was higher in the south of Sweden.Finally, the cumulated precipitation over 1 year was identified as a protective factor.

View Article: PubMed Central - PubMed

Affiliation: INRA,UMR1300 Biology,Epidemiology and Risk Analysis in Animal Health,CS 40706,F-44307 Nantes,France.

ABSTRACT
Ruminants are considered the main reservoir for transmission of Coxiella burnetii (Cb) to humans. The implementation of effective control measures against Cb in ruminants requires knowledge about potential risk factors. The objectives of this study were (i) to describe the spatial distribution of Q fever-infected dairy cattle herds in Sweden, (ii) to quantify the respective contributions of wind and animal movements on the risk of infection, while accounting for other sources of variation, and (iii) to investigate the possible protective effect of precipitation. A total of 1537 bulk milk samples were collected and tested for presence of Cb antibodies. The prevalence of test-positive herds was higher in the south of Sweden. For herds located in areas with high wind speed, open landscape, high animal densities and high temperature, the risk of being infected reached very high values. Because these factors are difficult to control, vaccination could be an appropriate control measure in these areas. Finally, the cumulated precipitation over 1 year was identified as a protective factor.

Show MeSH
Related in: MedlinePlus