Emerging Infectious Diseases

Tick-borne disease constitutes a serious challenge associated to human and animal illnesses, economic losses and  control measure. As well as other ruminants, camels in arid area are involved in these infections as host and/or carrier. The current study, reported infection of ticks infesting Tunisian dromedaries (Camelus dromedarius) by Coxiella burnetii and the endosymbiotic bacteria Candidatus Midichloria mitochondrii. A total of 327 non-engorged ticks, including 160 Hyalomma dromedarii (49%), 158 H. impeltatum (48.3%) and 9 H. excavatum (2.7%) removed from 412 one humped dromedaries were subjected to PCR amplification using specific primers. Coxiella burnetii and C.M. mitochondrii DNA were detected in 3.6% (12/327) and 8% (26/327) of tested ticks, respectively. However, no positive DNA camels’ blood sample was observed for both bacteria. The genetic characterization of obtained Coxiella strains based on the IS1111 and htpB genes revealed 100% of identity to the classified pathogenic C. burnetii with absence of all endosymbiosis related strains (Coxiella-like bacteria). The same applies to bacteria of the family Midichloriaceae genetic variants identified based on the 16SrRNA gene analysis revealed 100% of similarity to C.M. mitochondrii. These findings added to the growing evidence of the involvement of Hyalomma species in the active diffusion of these bacteria among camels, livestock and human. To our knowledge, this paper constitutes the first report highlighting the presence of the classified C. burnetii and the endosymbiont C.M. mitochondrii in Ticksinfesting camels from Tunisia. Interestingly, other investigations are needed to survey the zoonotic potential of these infectious agents among camels’ owners and other animals.