Understanding the long-lasting associations among humans, neglected dogs, tick-borne diseases, and core blood bacteria-related pathogenic taxa using next-generation sequencing

Background and Aim: Dogs are long-lasting companion animals, and ticks are the most common external parasites in dogs. An increase in the population of neglected domestic dogs has increased the risk of contact with ticks, especially in places where tick-borne diseases (TBDs) are endemic. We aimed to characterize the bacterial blood profiles of people who were either exposed (HE) or not exposed (HC) to tick bites using next-generation sequencing (NGS). Materials and Methods: In the present study, the bacteria observed in the blood of people exposed to tick bites were compared with those in the blood of people not exposed to tick bites in Northern Mexico. Human blood samples (n = 12) were analyzed, DNA was extracted, and the V3–V4 region of the 16S ribosomal RNA gene was amplified. In addition, NGS was performed on a MiSeq platform (Illumina), and the data were analyzed through Quantitative Insights into Microbial Ecology. Results: Differences in beta diversity were significant. In HEs, several potentially pathogenic bacterial taxa were found to be the most abundant: Kocuria ( x = 14.59%), Staphylococcus ( x = 3.05%), and Treponema ( x = 2.93%), in addition to Chlamydia, Clostridium, and Ehrlichia, which are considered TBDs. Conclusion: This study identified important differences in the bacterial composition of the HE and HC groups. In addition to Ehrlichia (a TBD considered a taxon), other bacterial pathogenic taxa, such as Chlamydia, Clostridium, Kocuria, Staphylococcus, and Treponema, were also observed in the tick bite-exposed group. Future studies with larger sample sizes should provide an improved understanding of the human blood microbiome profile by providing additional evidence of tick exposure, associated TBDs, and other pathogenic bacterial taxa. Keywords: Blood, Ehrlichia, microbiome, tick bites, tick-borne diseases, ticks.