الفهرس 
cover englishOnly 14 pages are availabe for public view
 |  | from | 205 |  |  |
| | | from | 205 | | |
Abstract
Rickettsioses have an epidemiological importance that includes pathogens, vectors, and hosts and have zoonotic importance. A total number of 461 blood samples of animals (200 dogs, 200 horses and 61 camels) were collected from three Egyptian provinces (Cairo, Giza and Sinai). In addition, 705 adult ticks were collected (601 ticks from dogs and 104 ticks from camels) including 9 nymphs, during a period extending from 2011 to 2014. The most important clinical signs were observed fever, anorexia, lethargy, anemia, enlargement of lymph node, ocular signs and emaciation. Meanwhile, the rest of animals were apparently healthy. Morphological identification of both male and female tick specimens by Light Microscope and Scanning Electron Microscope revealed that 100% of tick-infested dogs were Rhipicephalus sanguineus while 91.9% of tick-infested camels were Hyalomma dromedarii. The blood film staining with Gimenez stain revealed that 3 (2 dogs and 1 horse) were positive for Rickettsioses by finding of Rickettsiae stained red inside granulocytes. While, hemolymph staining of tick specimens by Gimenez stain showed that the prevalence rate was 11.89 % in Rh. sanguineus and 10.1 % in Hyalomma spp. OmpA and gltA genes amplification were performed to estimate the prevalence rate of Rickettsiae in animal hosts and their ticks which revealed that the infection rate was 18 % in dogs, 72 % in horses, 41 % in camels and 6.17 % in ticks. Moreover, the phylogenetic analyses of two genes (OmpA and gltA) and three intergenic spacers (mppA, dksA and rpmE) of Rickettsia species sequences were constructed based on Clustal W multiple alignments using two methods UPGMA and NJ, and revealed a novel strain of Rickettsia africae in H. marginatum on camel from Sinai province. In addition, the phylogenetic analyses based on Clustal omega suggested that Rickettsiae sequences which detected in animal hosts were three different strains of R. africae-like in camels and dogs, and the first record of R. massiliae-like in dogs. Moreover, the phylogenetic analyses of 18S rDNA, ITS2, 12S rDNA, CO1 and 16S rDNA were performed for molecular identification of Rh. sanguineus and H. dromedarii. The two tick species sequences analyses proved 96-100% sequences identities when compared with the reference data in Genbank records. The analyses revealed the molecular identification was in agreement with morphological identification. Moreover, the highest rickettsial infection rate was recorded in age groups of 2 to 3 years (42.8 %) in dogs, 13 to 16 years in horses (100 %) and 17 to 19 years in camels (80.0 %), female animals (26.7, 78.9 and 100 %) in dogs, horse and camels, respectively, Malino dogs (28.5 %), Arabic horses (100 %) and Abady camel breeds (56.8 %) and ticks-infested animals (15.3 and 42.8 %) in dogs and camels, respectively. Finally, the present studies confirm the suitability of mitochondrial DNA markers for reliable identification of ticks at both intra- and inter-species level over the nuclear ones. In addition, the detection of Rickettsiae in both animals’ species and tick vectors indicated that dogs, horses, camels and their tick vectors play a critical role as sentinels in an epidemiological approach of Rickettsioses in Egypt.