Highlighting zoonotic importance of synanthropic fleas through microbiome analysis

The role of domestic and peridomestic animals in vector-borne diseases is critical as they share a common environment with people having the potential to extend the network of pathogen transmission to humans. In the present study, amplicon sequencing was employed to characterize the microbial communities associated with five flea species (Archaeopsylla erinacei, Ctenocephalides felis, Spilopsyllus cuniculi, Pulex irritans and Ctenocephalides canis) collected from dogs, cats, and hedgehogs in Andalusia (Spain). The analysis focused on identifying the presence and infection rate of pathogenic bacteria within these synanthropic flea populations. The higher relative abundance of the Phylum Pseudomonadota was primarily attributed to the presence of the endosymbiont Wolbachia, along with consistently elevated levels of the genera Rickettsia and Bartonella across all flea species. This study reports, for the first time, the detection of Babesia sp. in all tested flea species, with the highest abundance observed in S. cuniculi collected from cats, emphasizing the need for further investigation into its potential implications as vectors. Our results also demonstrate that the microbiota composition of fleas is largely influenced by the host they parasitize. The study of microbiota allowed for the ecological separation of flea species, with individuals from these five species clustering distinctly each other.