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Objective Fleas are obligate ectoparasites of mammals and play an important role in the transmission of zoonotic pathogens, including Yersinia pestis . Describing empirical patterns of flea infestation across host communities is essential for understanding host–parasite associations in plague-endemic regions. The aim of this study is to investigate the relationship between fleas and their host animals by examining how host traits influence flea parasitism, with the goal of offering novel insights for future plague prevention strategies and related research. Methods From 2022 to 2025, small mammals were trapped in four counties in northern Xinjiang, China. A total of 723 individuals representing eight small mammal species were examined for flea infestation, including Spermophilus undulatus , Cricetulus migratorius , Mus musculus , and others. Fleas were collected from hosts and the surrounding environment and identified morphologically. Host and flea diversity were quantified using Simpson’s diversity index and Sullivan’s composite diversity index. Associations between host species identity, individual-level traits, and flea infestation probability and infestation intensity were evaluated using hurdle negative binomial (HNB) regression models. Results Spermophilus undulatus accounted for 65.98% of captured hosts and harbored the majority of collected fleas, primarily Citellophilus tesquorum and Frontopsylla elatoides . Flea prevalence was highest on S. undulatus (53.66%). HNB models indicated that flea infestation patterns were strongly associated with host species identity and selected host traits. Adult hosts exhibited higher odds of flea infestation but lower flea abundance conditional on infestation compared with immature individuals. Hosts with greater body mass carried significantly higher flea burdens, while male hosts tended to harbor more fleas than females, although this effect was marginal. Conclusion Flea infestation patterns in northern Xinjiang are closely associated with host species identity and individual-level traits. The dominant role of S. undulatus in host–flea associations highlights its potential epidemiological relevance and identifies it as a key species for future pathogen surveillance within local plague foci. These findings provide an empirical description of host–flea relationships and offer ecological context for flea surveillance in plague-endemic landscapes.
Zhang et al. (Fri,) studied this question.