Bacterial Communities Harboured by Amblyomma Hebraeum Infesting Small Stock in Mahikeng city, South Africa

Abstract

Ticks are important vectors of pathogens affecting livestock productivity and public health, yet their bacterial communities remain poorly characterized in many parts of South Africa. This study investigated the bacterial diversity and potential pathogenic bacterial etiology associated with Amblyomma hebraeum ticks collected from sheep and goats in Mahikeng, North West province. A total of 168 adult ticks were sampled across four villages. Microbiome profiling was performed using high-throughput sequencing of the V3–V4 hypervariable regions of the 16S rRNA gene on the Illumina MiSeq platform. High-throughput 16S rRNA sequencing revealed 16,193 ASVs in goat-derived ticks and 16,510 ASVs in those from sheep. Proteobacteria emerged as the dominant phylum across all samples, with ticks collected from goats showing a particularly high dominance of Rickettsia spp. (51.64% relative abundance), suggesting potential zoonotic risks. In contrast, ticks from sheep harboured significantly more diverse and evenly distributed bacterial communities, as indicated by Shannon (p = 0.0138) and Simpson (p = 0.0233) diversity indices, despite comparable species richness. A core microbiome comprising 1,374 ASVs (32.3%) was shared across all ticks, alongside 1,504 and 1,372 unique ASVs in goat- and sheep-derived ticks, respectively. Notably, several medically and veterinary-relevant genera, including Coxiella, Ehrlichia, Staphylococcus, Bacillus, Acinetobacter, Corynebacterium, and Streptococcus, were detected across both host groups. While total species richness was comparable between hosts, alpha diversity indices that account for evenness revealed host-based differences, and beta diversity patterns further showed clear separation of bacterial communities by host species. This study indicates that the host plays a crucial role as an ecological driver affecting the diversity of microbial communities associated with ticks. This study improves our understanding of the diversity, composition, and abundance of tick-associated microbiomes and pathogens in South African small ruminants. These insights support the development of microbiome-targeted strategies for detecting and controlling tick-borne diseases.