Tick species identification and molecular detection of tick-borne pathogens in blood and ticks collected from cattle in Egypt

Abstract

To address the lack of information on ticks infesting cattle in Egypt and the pathogens that they transmit, the current study aimed to (i) provide insight into tick species found on cattle in Egypt, (ii) identify the pathogens in ticks and their cattle hosts and (iii) detect pathogen associations in ticks and cattle. Tick samples and blood from their bovine hosts were collected from three different areas in Egypt (EL-Faiyum Oasis, Assiut Governorate and EL-Kharga Oasis). Tick species were identified by morphology and by sequence analysis of the cytochrome C oxidase subunit 1 (cox1) gene. Tick pools and blood samples from cattle were screened by the Reverse Line Blot hybridization (RLB) assay for the simultaneous detection of tick-borne pathogens, including Babesia, Theileria, Anaplasma, Ehrlichia, and Rickettsia spp., as well as the tick endosymbiont Midichloria mitochondrii. The RLB results were confirmed with specific conventional and semi-nested PCRs followed by sequencing. In total, 570 ticks (males, females and nymphs) were collected from 41 heads of cattle. Altogether 398 ticks belonged to the genus Hyalomma (397 Hyalomma excavatum and one Hyalomma scupense) while 172 ticks were identified as Rhipicephalus annulatus. Pooled H. excavatum ticks tested positive for several protozoa and bacteria with different minimum infection rates (MIRs): Theileria annulata (18.1 %), Babesia occultans (1.8 %), Anaplasma marginale (28.5 %), Anaplasma platys (0.25 %), Midichloria mitochondrii (11.6 %), Ehrlichia chaffeensis-like (1.8 %) and Ehrlichia minasensis (1 %). In R. annulatus, several agents were identified at different MIRs: T. annulata (2.3 %), B. bovis (0.6 %), A. marginale (18.0 %), A. platys (1.2 %), M. mitochondrii (2.9 %), E. minasensis (0.6 %). Pathogens co-detection in tick pools revealed A. marginale and T. annulata in 13.3 % samples followed by the co-detection of A. marginale and M. mitochondrii (8.4 %). In addition, triple co-detection with A. marginale, T. annulata and M. mitochondrii were found in 5.3 % of the tick pools. In cattle, the most common coinfection was with A. marginale and T. annulata (82.9 %) followed by the coinfection between A. marginale, T. annulata and B. bovis (4.9 %), A. marginale and B. bigemina (2.4 %) and finally the coinfection between T. annulata and B. occultans (2.4 %). Anaplasma platys, Babesia occultans, and E. minasensis were detected for the first time in Egypt in both cattle and ticks. These findings should be taken in consideration regarding human and animal wellbeing by the public health and veterinary authorities in Egypt.