Molecular prevalence and phylogenetic characterization of Francisella-like endosymbionts in ticks infesting camels and cattle from Southern Egypt

Ticks serve as vectors for numerous pathogens affecting human and animal health and harbor various microorganisms, including Francisella-like endosymbionts (FLEs), whose potential pathogenicity remains uncertain. In Egypt, data on FLEs, particularly in Southern Egypt, are limited, despite the importance of tick-borne pathogen surveillance in livestock. This study represents the first report of FLEs in Southern Egypt and the first detection of FLEs in Rhipicephalus annulatus in Egypt. A total of 726 ticks infesting cattle and camels were collected from various locations in Southern Egypt. Ticks were identified using both morphological and molecular techniques based on the 16S rRNA gene, and FLE detection was performed using PCR assays targeting a fragment of the Francisella 16S rRNA gene. Francisella DNA was detected in 60.1 % (288/479) of the examined ticks, with the highest prevalence in Hyalomma marginatum (100 %, 4/4), followed by Hyalomma dromedarii (74.8 %, 243/325), and R. annulatus (27.3 %, 41/150). Sequencing of 19 positive samples revealed that H. dromedarii (n = 13), H. marginatum (n = 2), and R. annulatus (n = 4) carried FLE sequences with 99-100 % similarity to strains previously identified in ticks worldwide. Given the high prevalence of FLEs in livestock-associated ticks, further research should focus on characterizing these strains, assessing their role in tick-borne pathogen ecology, and evaluating potential implications for human and animal health.