Landscape connectivity, habitat isolation, and tick-borne pathogen ecology

Habitat loss and forest fragmentation are often linked to increased
pathogen transmission, but the extent to which habitat isolation and
landscape connectivity affect disease dynamics through movement of disease
vectors and reservoir hosts has not been well examined. Tick-borne
diseases are the most prevalent vector-borne diseases in the US and on the
West Coast, Ixodes pacificus is one of the most epidemiologically
important vectors. We investigated the impacts of habitat fragmentation on
pathogens transmitted by I. pacificus and sought to
disentangle the effects of wildlife communities and landscape metrics
predictive of pathogen diversity, prevalence, and distribution. We
collected pathogen data for four co-occurring bacteria transmitted
by I. pacificus and measured wildlife parameters. We also used
spatial data and cost-distance analysis integrating expert opinions to
assess landscape metrics of habitat fragmentation. We found that landscape
metrics were significant predictors of tick density and pathogen
prevalence. However, wildlife variables were essential when predicting the
prevalence and distribution of pathogens reliant on wildlife
reservoir hosts for maintenance. We found that landscape structure was an
informative predictor of tick-borne pathogen richness in an urban matrix.
Our work highlights the implications of large-scale land management on
human disease risk.

栖息地丧失与森林碎片化常被认为与病原体传播加剧相关，但栖息地隔离及景观连通性通过病媒（disease vectors）和储存宿主（reservoir hosts）的移动对疾病动态（disease dynamics）产生影响的程度尚未得到充分研究。蜱传疾病（Tick-borne diseases）是美国及西海岸最常见的病媒传播疾病，太平洋硬蜱（Ixodes pacificus）是流行病学上最重要的病媒之一。我们研究了栖息地碎片化对太平洋硬蜱传播的病原体的影响，并试图厘清野生动物群落（wildlife communities）及景观指标（landscape metrics）对病原体多样性（pathogen diversity）、流行率（pathogen prevalence）和分布的预测效应。我们收集了太平洋硬蜱传播的四种共现细菌的病原体数据，并测定了野生动物参数（wildlife parameters）。此外，我们利用空间数据及整合专家意见的成本距离分析（cost-distance analysis），评估了栖息地碎片化的景观指标。研究发现，景观指标是蜱密度（tick density）和病原体流行率的显著预测因子。然而，在预测依赖野生动物储存宿主维持生存的病原体的流行率和分布时，野生动物变量（wildlife variables）至关重要。我们还发现，景观结构（landscape structure）是城市基质（urban matrix）中蜱传病原体丰富度（tick-borne pathogen richness）的有效预测因子。本研究强调了大规模土地管理（large-scale land management）对人类疾病风险（human disease risk）的潜在影响。