Molecular detection of Coxiella spp. and characterization of blood-feeding sources in tick species parasitizing domestic animals in cattle farms from Magdalena Medio, Colombia.

Coxiella burnetii is a globally distributed zoonotic bacterium responsible for Q fever in humans, with domestic ruminants serving as primary reservoirs. In Colombia, while livestock production is a vital economic sector, the dynamics of C. burnetii circulation among ticks and domestic animal hosts remain poorly understood. This study aimed to identify C. burnetii in hosts and ticks from two cattle farms in the Magdalena Medio region. Ticks were collected directly from domestic animal hosts through physical inspections and the use of the dragging technique on pasture vegetation and identified via morphological keys and COI barcoding as Rhipicephalus microplus s.l., predominating on cattle, Dermacentor nitens on equines, and Rhipicephalus sanguineus s.l. on dogs. Blood-meal analysis using PCR-HRM and sequencing identified feeding sources in equines, bovines, and humans, with human DNA detected in all larval pools. Following tick characterization, Coxiella spp. were screened by qPCR targeting the IS1111 insertion sequence, revealing a frequency of 10.5% in domestic animal hosts and 1.36% in ticks. Finally, phylogenetic analysis of 16S rRNA and rpoB genes confirmed the coexistence of C. burnetii (Clade A) in hosts and ticks, alongside Coxiella-like endosymbionts (Clade C), primarily in R. microplus s.l. These findings reveal complex tick-host interactions and confirm the molecular circulation of Coxiella spp. in tropical livestock systems. The results underscore the need to use multigene markers to differentiate pathogens from endosymbionts and suggest a potential human exposure risk, highlighting the importance of One Health surveillance in these agroecosystems.