Description:    Land use has been implicated as a major causal factor in the recent surge of emerging and reemerging zoonotic diseases worldwide. Whirling disease, a parasitic infection caused by the myxozoan, Myxobolus cerebralis , has led to major declines in wild trout populations within the Intermountain West of the USA and is suspected to be exacerbated by land and stream management practices that create favorable habitat for the oligochaete host, Tubifex tubifex . Our objectives were to quantify relationships between whirling disease risk and (1) land use and (2) characteristics of the oligochaete host community within four major watersheds in western Montana. Risk was quantified by the severity and prevalence of infection in caged sentinel rainbow trout. A geographic information system (GIS) was used to model land use (e.g., agriculture, mines) within watersheds. Importance of predictor variables was assessed using regression tree and random forest analyses. A low proportion of riparian forest, high road density, high oligochaete density, and high Limnodrilus hoffmeisteri density were identified as important predictors of high risk. Although we did not examine the mechanisms underlying these correlations, a low proportion of riparian forest and a high road density likely increase stream sedimentation, thus, increasing habitat for oligochaetes. Although relationships identified are not necessarily causal, the ability to predict areas most at risk of M. cerebralis establishment and proliferation using broad scale predictors should serve as a useful management tool within Montana and elsewhere. Content Type Journal Article Category Research Article Pages 1-16 DOI 10.1007/s10980-012-9810-8 Authors Stephanie McGinnis, Department of Ecology, Montana State University, Bozeman, MT 59717, USA Billie L. Kerans, Department of Ecology, Montana State University, Bozeman, MT 59717, USA Journal Landscape Ecology Online ISSN 1572-9761 Print ISSN 0921-2973