Francisella-Like Endosymbionts and Rickettsia Species in Local and Imported Hyalomma Ticks

Hyalomma ticks (Acari: Ixodidae) are hosts forFrancisella -like endosymbionts (FLE) and may serve as vectors of zoonotic disease agents. This study aimed to provide an initial characterization of the interaction betweenHyalomma and FLE and to determine the prevalence of pathogenicRickettsia in these ticks.Hyalomma marginatum ,Hyalomma rufipes ,Hyalomma dromedarii ,Hyalomma aegyptium , andHyalomma excavatum ticks, identified morphologically and molecularly, were collected from different hosts and locations representing the distribution of the genusHyalomma in Israel, as well as from migratory birds. A high prevalence of FLE was found in allHyalomma species (90.6%), as well as efficient maternal transmission of FLE (91.8%), and the localization of FLE in Malpighian tubules, ovaries, and salivary glands inH. marginatum . Furthermore, we demonstrated strong cophylogeny between FLE and their host species. Contrary to FLE, the prevalence ofRickettsia ranged from 2.4% to 81.3% and was significantly different betweenHyalomma species, with a higher prevalence in ticks collected from migratory birds. UsingompA gene sequences, most of theRickettsia spp. were similar toRickettsia aeschlimannii , while a few were similar toRickettsia africae of the spotted fever group (SFG). Given their zoonotic importance, 249 ticks were tested for Crimean Congo hemorrhagic fever virus infection, and all were negative. The results imply thatHyalomma and FLE have obligatory symbiotic interactions, indicating a potential SFGRickettsia zoonosis risk. A further understanding of the possible influence of FLE onHyalomma development, as well as on its infection withRickettsia pathogens, may lead to novel ways to control tick-borne zoonoses.IMPORTANCE This study shows thatFrancisella -like endosymbionts were ubiquitous inHyalomma , were maternally transmitted, and cospeciated with their hosts. These findings imply that the interaction between FLE andHyalomma is of an obligatory nature. It provides an example of an integrative taxonomy approach to simply differentiate among species infesting the same host and to identify nymphal and larval stages to be used in further studies. In addition, it shows the potential of importedHyalomma ticks to serve as a vector for spotted fever group rickettsiae. The information gathered in this study can be further implemented in the development of symbiont-based disease control strategies for the benefit of human health.