First report on Bartonella henselae in dromedary camels (Camelus dromedarius)

Bartonellosis is one of the clinically underdiagnosed emerging bacterial diseases among domestic livestock, particularly in camels. Until now, the natural infection of camels with Bartonella species was not investigated in Tunisia. In the attempt of filling this gap in knowledge, a total of 412 dromedary camels (Camelus dromedarius) as well as 300 associated ticks (Hyalomma dromedarii (160; 53.4%), H. impeltatum (131; 43.6%) and H. excavatum (9; 3%) were screened for the presence of Bartonella spp. by PCR followed by a sequencing step through the amplification of the rpoB gene. Positive samples were then tested and further characterized by the combined use of the ftsZ and gltA genes. Fifteen camels (3.6%) were found to be positive to Bartonella spp. However, there was no evidence of Bartonella DNA in any of the analyzed ticks. Risk factors' analysis shows that camels derived from arid and semi-arid bioclimatic areas were more infected than those originated from desert area. Molecular characterization and phylogenetic analysis revealed the occurrence of novel B. henselae genotypes closely related to those isolated from humans, cats, and lions. By combining the characteristics of each single gene with those of concatenated sequences, we report here the first molecular detection of B. henselae in the dromedary camel suggesting a possible involvement of camelids as hosts or reservoirs in the transmission cycle of this emerging bacterium in arid and saharan areas.