Genetic characterization of Coxiella burnetii in Amblyomma varigatum ticks from North-central Nigeria: public health importance

Aim: The purpose of this pilot study was to genetically identify and characterize Coxiella burnetii from Amblyomma varigatum ticks collected on cattle in North central Nigeria. Materials and Methods: A total of 40 partially fed ticks morphologically identified as adult A. variegatum ticks collected from cattle owned by Fulani pastoralists were evaluated for the presence of C. burnetii using PCR, cloning, and sequencing of the heat shock polypeptide gene htpB. Results: C. burnetii DNA was detected in 10 (25%) of the ticks analyzed. Sequences for the C. burnetii gene htpB detected in our samples had 99-100% identity to all other C. burnetii that have been described and that are deposited in the GenBank database. Phylogenetic analysis using neighbor-joining method indicates the clustering of C. burnetii sequences from our study areas with those collected from Oyo state, South-western Nigeria and Spain. Conclusion: This study shows a high infection rate of C. burnetii in A. variegatum ticks in the study areas. Phylogenetic inferences indicates that the strain of C. burnetii found in the North central states of Plateau and Nasarawa were same as those previously reported in the South western state of Oyo. The presence of this pathogen in naturally occurring A. variegatum tick populations could present an additional risk of Q-fever disease to humans, especially to the pastoralists that are closely associated with their animals and are easily exposed to tick bites. Therefore, further studies are needed to assess the competence of A. variegatum ticks as vectors of C. burnetii pathogens.