Molecular Detection and Prevalence of Coxiella burnetii in Ticks from Namibia: A Regional and Genus-Specific Analysis.

Coxiella burnetii (C. burnetii) is a zoonotic pathogen with significant public and veterinary significance. Whilst livestock are considered as primary reservoirs of the pathogen, ticks play a crucial role in transmission and environmental contamination. Within Namibia, there is serological evidence of pathogen circulation in livestock and wildlife. However, no study has ever been conducted to determine the prevalence of C. burnetii in ticks in Namibia. Thus, this study investigated the prevalence and genetic diversity of C. burnetii in ticks collected from two different ecological settings. A total of 502 ticks (Rhipicephalus, Amblyomma, and Hyalomma) collected from 278 cattle (139 from each of the tropical Zambezi and arid Khomas regions) were screened for C. burnetii using PCR targeting the genus-specific 16S rRNA and the species-specific isocitrate dehydrogenase (icd) genes. Based on the isocitrate dehydrogenase (icd) genes, an overall prevalence of 8% (40/502) was observed for C. burnetii, with significantly higher infection rates observed in the more tropical Zambezi region (11.7%) when compared to the more arid Khomas region (2.8%) [p = 0.0005]. Variation was observed amongst tick species [p = 0.00121], with prevalence being slightly higher in Amblyomma ticks (12.9%) and Hyalomma (10.6%) as compared to Rhipicephalus ticks (3.6%). Phylogenetic analysis based on the icd gene sequences confirmed 99-100% identity with C. burnetii strains from around the world, thus confirming the circulation of this pathogen in ticks, ultimately supporting their potential role in the epidemiology of this pathogen in Namibia. The observed regional prevalence difference could be driven by variation in the ecological factors, with the subtropical climatic conditions of Zambezi likely favoring higher tick infection rates. Our findings highlight the need for One Health-based surveillance to mitigate the risks associated with pathogen risk. This study provides the first molecular evidence of C. burnetii in ticks in Namibia, highlighting their role in the pathogen's epidemiology and providing relevant information for informed control strategies.