Molecular Investigation on Tick-Borne Hemoparasites and Coxiella burnetii in Dromedary Camels (Camelus dromedarius) in Al Dhafra Region of Abu Dhabi, UAE

Simple Summary Dromedary camels (Camelus dromedarius), or Arabian camels, are mainly widespread in arid regions from the east of Asia to the north of Africa. Many species of parasites/arthropods affect camels, including ticks, able to transmit pathogens to animals and humans. Authors investigated the presence of blood parasites in n = 93 camels with acute clinical signs and in n = 72 ticks collected from these camels in Al Dhafra region of Abu Dhabi, United Arabian Emirates, through molecular techniques. All the 72 ticks collected were identified as Hyalomma dromedarii species and were found negative for pathogen DNA. DNA investigations on camel blood samples showed a positivity for tick-transmitted pathogens in 15 heads (16.1%): 15 Anaplasma phagocytophilum (11.8%), Coxiella burnetii (3.2%), and Babesia/Theileria spp. (2.1%). Coinfection of A. phagocytophiulm and C. burnetii was detected in a camel. C. burnetii sequences from our samples showed a high phylogenetic relatedness to strains from Europe, Africa, and Asia. The study represents the first molecular investigation on tick-borne pathogens in camels from United Arabian Emirates, and it highlights the possible risk of infection for humans working in close contact with camels. Camels represent an important resource for inhabitants of the most arid regions of the world and their survival is mainly related to environment conditions including the risk of parasitic diseases, which may represent a significant cause of losses in livestock production of these areas. Camels may be parasitized by several hematophagous arthropods, which can be vectors of several diseases including zoonosis. This study aimed to investigate in dromedary camels and their ticks the importance of tick-borne hemoparasites that might be responsible for a recent and obscure morbidity of camels in Al Dhafra region of Abu Dhabi, UAE. Blood samples and ticks from 93 naturally infected camels belonging to 36 herds, affected by variable acute clinical syndromes lasting from 3 to 5 days, were analyzed through molecular techniques for specific DNA presence of different blood pathogens: Anaplasma marginale/Anaplasma ovis, Anaplasma phagocytophilum, Coxiella burnetii, Babesia spp., and Theileria spp. DNA. All the 72 ticks collected belonged to the Hyalomma dromedarii species and were negative for blood pathogens. n = 15 camels (16.1%) were found positive to the following tick-borne hemoparasites: A. phagocytophilum 11 (11.8%), Coxiella burnetii 3 (3.2%), and Babesia/Theileria spp. 2 (2.1%). One singular camel showed coinfection of C. burnetii and A. phagocytophiulm. Genetic profile of C. burnetii showed a high phylogenetic relatedness to European, Asian and African C. burnetii strains. This is the first laboratory investigation on tick-borne pathogens in camels in UAE, and the first report of A. phagocytophilum and C. burnetii. Moreover, since the detected pathogens are recognized pathogens for humans, this study highlights the zoonotic risk for humans working in camel husbandry.

Automated summary

This study is the first laboratory investigation on tick-borne pathogens in camels in the UAE, revealing a certain proportion of camels infected with tick-transmitted pathogens, including a single camel with coinfection. The genetic profile of Coxiella burnetii shows a high phylogenetic relatedness to strains from Europe, Asia, and Africa.