Marked host association and molecular evidence of limited transmission of ticks and fleas between sympatric wild foxes and rural dogs.

Wild and domestic carnivores share ectoparasites, although molecular evidence is lacking. The goals of this study were to describe tick and flea infestation in sympatric free-ranging dogs Canis lupus familiaris (Linnaeus, 1758) (Carnivora: Canidae) and Andean foxes Lycalopex culpaeus (Molina, 1782) (Carnivora: Canidae) and to determine whether interspecific transmission occurs. Fleas and ticks retrieved from 79 foxes and 111 dogs in the human-dominated landscapes of central Chile were identified and a subset of specimens characterized by PCR and amplicon sequencing. Each ectoparasite species was clearly associated with a host: abundance and occurrence of Rhipicephalus sanguineus (Latreille 1806) (Acari: Ixodidae) and Ctenocephalides spp. (Siphonaptera: Pulicidae) were significantly higher in dogs than in foxes, whereas the opposite was true for Amblyomma tigrinum (Koch, 1844) (Acari: Ixodidae) and Pulex irritans (Linnaeus, 1758) (Siphonaptera: Pulicidae). Genetic analyses of a subset of ectoparasites revealed that dogs and foxes shared a limited number of nucleotide sequence types, suggesting that the interspecific transmission of these ectoparasites happens infrequently. Data also indicated that the ecological association and biological cycles of ticks and fleas determine the ectoparasite fauna of sympatric carnivores. In conclusion, our study shows that cross-species transmission should be assessed at a molecular level.