Molecular evidence for mixed infection of Anaplasma sp. and Ehrlichia sp. in dromedary camels of United Arab Emirates.

Tick borne bacterial infections are an emerging threat to dromedary camels, mostly by pathogens of the rickettsial family Anaplasmatacea.They include mainly two genera, Anaplasma and Ehrlichia that are obligate intracellular organisms. Reports of Anaplasma infections in camels are common but reports of Ehrlichia are rare. This study was undertaken to get an insight into the magnitude of the relative occurrence of Anaplasma and Ehrlichia infections in dromedary camels of Al Ain, Abu Dhabi, UAE. A total of 160 camels were initially screened using rRNA-based PCR and subsequently with chaperon Gro EL specific primers and identified two Anaplasmatacea-related bacterial pathogens. The Anaplasma lineage was of common occurrence, accounting for 51.3% of solo infections where as a smaller cohort, 8.1%, was infected exclusively with the Ehrlichia lineage. About 40.5% of the infected animals tested positive for both lineages. Thus 91.9% infections carried Anaplasma lineage, whereas 48.6% carried the Ehrlichia lineage. Anaplasma lineage (Candidatus Anaplasma camelii) identified in this study is closely related to Anaplasma platys, based on sequence analysis. A. platys is primarily a canine pathogen that infects platelets. Ehrlichia lineage (Candidatus Ehrlichia regneryi) bacteria that infect macrophages and monocytes also showed a close relationship with the canine agent, Ehrlichia canis. This is the first report of Ehrlichia in camels of UAE. We also report the co infection of both pathogens in the same animal for the first time in camels. These findings warrant extensive research on the transmission dynamics and biological characteristics of these pathogens.