A systematic review of the microbiome of Hyalomma Koch, 1844 ticks using next-generation sequencing of the 16S ribosomal RNA gene.

Background and aim: Ticks are critical vectors of pathogens affecting humans and livestock globally. The microbiome of ticks, comprising diverse bacterial communities, plays a crucial role in tick biology and vector competence. Hyalomma ticks are prominent in the Middle East and North Africa (MENA) region and are known carriers of significant pathogens. This study aimed to systematically evaluate existing literature regarding the microbiome composition of Hyalomma ticks in the MENA region, identify predominant bacterial genera, and highlight knowledge gaps.

Materials and methods: A systematic literature search was conducted using four databases: ScienceDirect, PubMed, Google Scholar, and Scopus. The search covered studies published between 2014 and 2024 employing 16S ribosomal RNA gene sequencing to analyze microbiomes of Hyalomma ticks within the MENA region. Studies not fulfilling these criteria were excluded through independent assessment by two authors.

Results: Out of 1,220 screened articles, seven studies met inclusion criteria, involving five Hyalomma species: Hyalomma dromedarii, Hyalomma anatolicum, Hyalomma excavatum, Hyalomma marginatum, and Hyalomma scupense. Most studies (57.14%) focused on H. dromedarii, primarily collected from camels. The geographical distribution of studies included the United Arab Emirates (42.86%), Saudi Arabia (28.57%), Iran (14.29%), and Tunisia (14.29%). Common bacterial genera identified across multiple studies included Acinetobacter, Bacillus, Flavobacterium, Francisella, Rickettsia, Staphylococcus, Pseudomonas, and Corynebacterium. However, substantial gaps were noted, particularly concerning variations related to tick lifecycle stages, host interactions, temporal dynamics, and extensive geographic coverage within the MENA region.

Conclusion: This systematic review underscores the presence of key bacterial genera within Hyalomma ticks across the MENA region, revealing their potential roles in tick biology and pathogen transmission. Major research gaps identified include limited geographical scope, insufficient exploration of microbiome variation across tick life stages, host-specific interactions, and the environmental factors influencing microbial communities. Addressing these gaps through comprehensive, longitudinal, and multi-regional studies is imperative for improving public health strategies and developing targeted tick-control methods.