Dromedary camels (Camelus dromedarius) are widely distributed in Africa, the Middle East and northern India. In this study, we aimed to detect tick-borne pathogens through investigating prokaryotic and eukaryotic microorganisms in camel blood based on a metagenomic approach and then to characterize potentially pathogenic organisms using traditional molecular techniques. We showed that the bacteria circulating in the blood of camels is dominated by Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria. At the genus level, Sediminibacterium, Hydrotalea, Bradyrhizobium and Anaplasma were the most abundant taxa. Eukaryotic profile was dominated by Fungi, Charophyta and Apicomplexa. At the genus level, Theileria was detected in 10 out of 18 samples, while Sarcocystis, Hoplorhynchus and Stylocephalus were detected in one sample each. Our metagenomic approach was successful in the detection of several pathogens or potential pathogens including Anaplasma sp., Theileria ovis, Th. separata, Th. annulate, Th. mutans-like and uncharacterized Theileria sp. For further characterization, we provided the partial sequences of citrate synthase (gltA) and heat-shock protein (groEL) genes of Candidatus Anaplasma camelii. We also detected Trypanosoma evansi type A using polymerase chain reaction (PCR) targeting the internal transcribed spacer 1 (ITS1) region. This combined metagenomic and traditional approach will contribute to a better understanding of the epidemiology of pathogens including tick-borne bacteria and protozoa in animals.

IThis study was designed for the investigation of the effect of infection by Trypanosoma evansi on the changes of reproductive indices of the testis, causing reproductive failure in dromedary bulls (Camelus dromedarius). Seventy-five bulls were used for monitoring of the changes in the semen characteristics, reproductive hormones, hematobiochemical profiles, histopathological characters in the testis, and oxidative biomarkers. The animals were divided into two groups. Group A represented the uninfected or control group, while group B represented the infected group. Group B was again divided into two subgroups, such as acute and chronic infected animals. Results showed that the semen analysis of infected camels revealed the presence of alterations in the morphology of sperms, especially the heads and tails, as compared to control animals. The hormonal profile indicated a significant decrease in the luteinizing hormone, follicle- stimulating hormone, and testosterone levels, accompanied by the rise in the cortisol level in infected camels compared with the negative control. The histopathology and testicular degeneration were found to be associated with other disorders in infected camels. The oxidative profile and protein oxidation were promoted in infected testicles, indicating the occurrence of harmful effects in the cell. It is concluded that T. evansi infection in dromedary bulls causes severe damage to the testicular tissue and decreases the reproductive hormone levels associated with severe morphological disorders in sperms due to oxidative stress resulting from the infection. All these findings indicate that T. evansi can cause reproductive failure and fertility damage.