Defining the bacterial microbiome of ticks in Chongwe and Chisamba Districts of Zambia

Background: The microbiome composition of an arthropod vector may impede the growth of some pathogens, aid colonisation by pathogens or affect vector behaviour in ways that impact the transmission of pathogens. In Zambia, little is known of the microbial communities hosted by ticks and how pathogens like Rickettsia play a role in the microbiome composition. Objective: This study sought to determine the microbiome of Rickettsia -negative and Rickettsia -positive ticks in selected districts of Zambia. Methods: This was a cross-sectional study carried out on 94 ticks collected from cattle in Chongwe and Chisamba districts. The overall prevalence of Rickettsia spp. was detected using PCR amplification of the ompB gene. Thereafter, both Rickettsia -negative and positive ticks underwent 16S rRNA gene amplification and Illumina highthroughput sequencing. Data was analysed using QIIME2 analysis pipeline. Results: The prevalence of Rickettsia was found to be 47.9% (45/94) with prevalence in Amblyomma at 78.5% (22/28), Hyalomma at 68.9% (20/29) and Rhipicephalus having the lowest at 8.1% (3/37). Proteobacteria, Firmicutes, Actinobacteriota and Euryachaeota were the most common phyla, while endosymbionts were uncommonly detected in the ticks. Further analysis showed significant differences in microbiome composition based on Rickettsia detection status ( p = 0.001) and location ( p = 0.001), based on the alpha diversity Shannon index, Bray Curtis beta diversity and PERMANOVA, whilst differences according to life stage, tick species and genus was only shown based on the Bray Curtis beta diversity and PERMANOVA analysis. Conclusion: Ultimately, this study provides valuable insights into the structure of the tick microbiome in parts of Zambia and how it is affected by the presence of Rickettsia .