The ecology of avian influenza viruses in wild dabbling ducks (<i>Anas</i> spp.) in Canada - Fig 2

<p>Predicted probability (solid line) and 95% CI (dashed lines) of AIV infection in dabbling ducks in the Prairie Provinces (a) and Eastern Canada (b) as a function of population density. Probabilities were estimated based on the best-approximating model (Tables <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0176297#pone.0176297.t001" target="_blank">1</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0176297#pone.0176297.t002" target="_blank">2</a>), with other variables set to their model reference category over the dataset as shown in the reported tables (HY male ducks (Prairie) or mallards (East) in Aug 2007) and at their mean values for temperature and percent HY. The distributions of data points are presented as rug plots along x axes (i.e., a vertical bar represents each sample) with different scales because duck density is higher in the Prairie Provinces than in Eastern Canada.</p

Annual variation in predicted probability of AIV infection in dabbling ducks in the Prairie Provinces (left) and Eastern Canada (right).

<p>Vertical lines represent 95% CI. Probabilities were estimated based on the best-approximating model (Tables <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0176297#pone.0176297.t001" target="_blank">1</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0176297#pone.0176297.t002" target="_blank">2</a>), with other variables set to the reference category over the dataset (HY male ducks (Prairie) and mallards (East) in August and at their mean values for mean temperature, population density and percent HY, where applicable). Sample sizes for each region and year are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0176297#pone.0176297.s002" target="_blank">S2 Table</a>.</p

The ecology of avian influenza viruses in wild dabbling ducks (<i>Anas</i> spp.) in Canada

<div><p>Avian influenza virus (AIV) occurrence and transmission remain important wildlife and human health issues in much of the world, including in North America. Through Canada’s Inter-Agency Wild Bird Influenza Survey, close to 20,000 apparently healthy, wild dabbling ducks (of seven species) were tested for AIV between 2005 and 2011. We used these data to identify and evaluate ecological and demographic correlates of infection with low pathogenic AIVs in wild dabbling ducks (<i>Anas</i> spp.) across Canada. Generalized linear mixed effects model analyses revealed that risk of AIV infection was higher in hatch-year birds compared to adults, and was positively associated with a high proportion of hatch-year birds in the population. Males were more likely to be infected than females in British Columbia and in Eastern Provinces of Canada, but more complex relationships among age and sex cohorts were found in the Prairie Provinces. A species effect was apparent in Eastern Canada and British Columbia, where teal (<i>A</i>. <i>discors</i> and/or <i>A</i>. <i>carolinensis</i>) were less likely to be infected than mallards (<i>A</i>. <i>platyrhynchos</i>). Risk of AIV infection increased with the density of the breeding population, in both Eastern Canada and the Prairie Provinces, and lower temperatures preceding sampling were associated with a higher probability of AIV infection in Eastern Canada. Our results provide new insights into the ecological and demographic factors associated with AIV infection in waterfowl.</p></div

Sampling locations for <i>Anas</i> spp. for Canada’s Inter-agency Wild Bird Influenza Survey, 2005–2011.

<p>Sections indicate duck population survey strata for which population density was estimated in spring. Star: British Columbia; Round dots: Prairie Provinces; Triangles: Eastern Canada.</p

Maximum likelihood estimates of fixed effects in the best-approximating model of AIV infection in the Prairie Provinces.

<p>Maximum likelihood estimates of fixed effects in the best-approximating model of AIV infection in the Prairie Provinces.</p

Predicted probability (solid line) and 95% CI (dashed lines) of AIV infection in dabbling ducks in Eastern Canada as a function of local mean daily temperature two weeks preceding sampling.

<p>Probabilities were estimated based on the best-supported model (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0176297#pone.0176297.t001" target="_blank">Table 1</a>), with other variables set to the reference category over the dataset (HY male mallards in Aug 2007) and at their mean values for population density and percent HY). The distribution of data points is presented as rug plots along the x axis (i.e., a vertical bar represents each sample).</p

Maximum likelihood estimates (with 95% CI) of covariate parameters in the best-approximating model fitted to estimate the variation in AIV infection probability in dabbling ducks (<i>Anas</i> spp.) in Eastern Canada.

<p>Maximum likelihood estimates (with 95% CI) of covariate parameters in the best-approximating model fitted to estimate the variation in AIV infection probability in dabbling ducks (<i>Anas</i> spp.) in Eastern Canada.</p

Maximum likelihood estimates of effects in the best-approximating model of AIV infection in BC.

<p>Maximum likelihood estimates of effects in the best-approximating model of AIV infection in BC.</p

BWTE_data

BWTE_dat

List of outcome and explanatory variables used in models examining demographic and spatiotemporal determinants of low pathogenic avian influenza virus infection in Blue-winged Teal in Canada and the United States, 2007–10.

<p>List of outcome and explanatory variables used in models examining demographic and spatiotemporal determinants of low pathogenic avian influenza virus infection in Blue-winged Teal in Canada and the United States, 2007–10.</p