Flea sharing among sympatric rodent hosts: implications for potential plague effects on a threatened sciurid

Abstract

For vector‐borne diseases, the abundance and competency of different vector species and their host preferences will impact the transfer of pathogens among hosts. Sylvatic plague is a lethal disease caused by the primarily flea‐borne bacterium Yersinia pestis. Sylvatic plague was introduced into the western United States in the early 1900s and impacts many species of rodents. Plague may be suppressing populations of the threatened northern Idaho ground squirrel (Urocitellus brunneus) if a competent flea community is allowing plague to be maintained within the few extant sites that support this rare ground squirrel. We collected fleas from four species of sympatric rodents in central Idaho: northern Idaho ground squirrels, Columbian ground squirrels (Urocitellus columbianus), yellow‐pine chipmunks (Tamias amoenus), and deer mice (Peromyscus maniculatus). We evaluated which flea species were present and whether fleas were shared among the rodent community. We documented seven species of fleas among 3356 fleas collected from the four host species of rodents, and all seven species of fleas are known vectors of plague. Three of the seven flea species were detected on all four rodent species, demonstrating potential for spillover of plague (bridge vectors) in the rodent community. We used generalized linear mixed models to evaluate which abiotic and biotic factors influence flea abundance (total number of fleas, regardless of flea species, on each individual host of the four rodent host species). Factors that impacted flea abundance varied among the four host species, but flea abundance: (1) changed over summer depending on host species, (2) was greater on males, and (3) was impacted by summer and winter precipitation depending on host species. Our results suggest this diverse flea community has the capacity to transfer Y. pestis among populations of the four rodents if Y. pestis is present. Furthermore, the disease may be more likely to persist in some locations than others, those that have higher flea abundances, more sympatric hosts, or optimal conditions for fleas, and such high‐risk sites can be identified based on their abiotic and biotic factors.

Host-pathogen-vector continuum in a changing landscape: Drivers ofBartonellaprevalence and evidence of historic spillover in a multi-host community

“…Several ectoparasites (e.g., Rhipicephalus sp, Xenopsylla sp 1) showed a wider host range, presumably due to their ability to infect multiple locally available hosts [61]. These results are consistent with previous studies and indicate that host sharing among vectors is more common than previously believed [62]. Such non-specific host-ectoparasite associations can facilitate transmission of several pathogens, making their ecology a crucial part of vectorborne pathogen dynamics [63].…”

“…Rhipicephalus sp , Xenopsylla sp 1 ) showed a wider host range, presumably due to their ability to infect multiple locally available hosts [73]. As observed elsewhere [74], host sharing was the predominant pattern observed in the community. Such generalist ectoparasites can facilitate the transmission of pathogens between hosts [75], making their ecology a crucial part of vector-borne pathogen dynamics.…”

Environmental suitability of Yersinia pestis and the spatial dynamics of plague in the Qinghai Lake region, China

“…Also, at lower elevations, the forest and thick grass could be harmful to plague hosts, while at higher elevations, there would be lack of food (Qian et al 2014). The shared distribution of rodents, fleas, and human beings increases the danger of infection and epidemic potential of the plague, especially for farmers who live within the higher probability areas (Nyirenda et al 2017;Goldberg et al 2020), such as those identified in our map.…”

Host phylogeny and ecology, but not host physiology, are the main drivers of (dis)similarity between the host spectra of fleas: application of a novel ordination approach to regional assemblages from four continents

“…8000 g) and a much smaller Phodopus sungorus (average body mass 33.2 g). Mean abundance attained by fleas on a host may or may not correlate positively with host size (Kiffner et al, 2013;Goldberg et al, 2020). No study that aims to test the effect of a host's BMR on flea abundance has been performed, but indirect evidence suggests that this effect is unlikely.…”