Assessment of bacterial diversity in Hyalomma aegyptium, H. marginatum and H. excavatum ticks through tag-encoded pyrosequencing

Ticks are among the most significant human-biting ectoparasites and they play a major role in transmission of many pathogenic agents to humans. In the present study, three species of Hyalomma ticks, Hyalomma aegyptium , H. marginatum and H. excavatum , were examined for the presence of zoonotic bacteria, both male and female ticks alike. Examination of microbial diversity with tag-encoded pyrosequencing indicates that H. marginatum and H. excavatum were more diversity rich than H. aegyptium . Although numerous pathogenic and non-pathogenic bacterial genera were detected, including Acidovorax , Bacillus , Bacteroides , Bdellovibrio , Clostridium , Curvibacter , Escherichia , Flavobacterium , Limnohabitans , Paenibacillus , Ralstonia , Sarcina , Sediminibacterium , Segetibacter Stenotrophomonas and Variovorax , the predominant zoonotic bacteria represented in these ticks were genera Borrelia, Francisella, and Rickettsia. To the authors’ knowledge, this work represents the first detection of Yersinia enterocolitica in the tick H. excavatum , raising questions regarding the vector competency of this tick, as well as associations of different disease representations perhaps through previously unforeseen routes of pathogen introduction. Likewise, similar questions are related to the presence of Legionella pneumophila in one H. excavatum sample.