We describe Yersinia pestis minimum infection prevalence in fleas collected from Tamias spp. chipmunks in the Sierra Nevadas (California, USA) during 2013-2015. Y. pestis-positive fleas were detected only in 2015 (year of plague epizootic), mostly in T. speciosus chipmunks at high-elevation sites. Plague surveillance should include testing vectors for Y. pestis.
Keywords: California; Sierra Nevada; Siphonaptera; Tamias alpinus; Tamias speciosus; United States; Yersinia pestis; Yosemite National Park; bacteria; chipmunk fleas; disease ecology; fleas; host–parasite; host–pathogen; infection prevalence; plague; rodents; surveillance; vector-borne infections; vectorborne disease; zoonoses.