A glimpse of the bacteriome of Hyalomma dromedarii ticks infesting camels reveals human Helicobacter pylori pathogen

Abstract

Introduction: The tick Hyalomma dromedarii is predominant in camels of Saudi Arabia and harbor multiple pathogens causing disease in humans and animals. Knowing the bacterial community of ticks is crucial for surveillance of known and newly emerging pathogens. Yet, the bacteriome of H. dromedarii remain unexplored to date.

Methodology: In a cross-sectional survey, we used V3-V4 region of 16S rRNA to characterize the bacteriome of 62 whole H. dromedarii tick samples collected from camels found in Hofuf city in Saudi Arabia.

Results: Sequencing results yielded 217 species incorporated into 114 genera, which in turn belong to the dominant phylum Proteobacteria (98%) followed by Firmicutes (1.38%), Actinobacteria (0.36%), Bacteroidetes (0.17%), meanwhile the phyla Cyanobacteria, Verrucomicrobia and unclassified bacteria were rarely detected. Francisella endosymbiont dominated the bacteriome of H. dromedarii ticks with average abundance of 94.37% and together with Salincoccus sp. accounted for 94.51% of the average sequences. The remaining bacteriome consisted of low abundance of potential pathogens and environmental bacteria. Of these pathogens, we found Helicobacter pylori in the tick H. dromedarii for the first time. Notably, Anaplasma, Ehrlichia and Rickettsia pathogens known to be found in H. dromedarii ticks were not detected.

Conclusion: This first preliminary study advances our knowledge about the bacterial community of H. dromedarii ticks and provides a basis for pathogen surveillance and studying the influences of symbionts on vector competence. Presence of pathogens in ticks, raise concerns about potential transmission of these agents to humans or animals.