MOLECULAR DIAGNOSIS OF RICKETTSIAE INFECTING CAMELS AND IXODID TICKS IN EGYPT

Abstract

Rickettsioses including their pathogens, vectors, and hosts have an epidemiological importance and zoonotic importance. The objective of the present article was to define the prevalence and genotypic properties of Rickettsia in camels and their ticks in Egypt. Sixty one blood samples and 99 adult ticks were taken from camel hosts from Cairo, Giza and Sinai, during a period extending from 2013 to 2014. Based on the morphological identification of both male and female tick specimens, 91.9 % of the collected ticks were Hyalomma dromedarii. The prevalence of Rickettsia in camels using Gimenez staining technique and PCR was 0 and 41 %, respectively. The rickettsiae infection in ticks recorded 10.1 and 1.01 %, by Gimenez stain and PCR, respectively. Further, the phylogenetic analysis was conducted based on the sequences of OmpA and gltAgenes and three intergenic spacers (mppA, dksA and rpmE) of Rickettsia species. The phylogenetic analyses revealed a novel strain of Rickettsia africae in Hyalomma marginatum that was collected from camel in Sinai province. In addition, the phylogenetic analysis based on Clustal omega suggested that Rickettsia sequences which detected in camels were R. africae. Moreover, the highest Rickettsial infection rate was recorded in age groups of 17 to 19 years (80.0 %), Abady camel breeds (56.8 %) and ticks-infested camels (42.8 %). Concerning hematological changes, macrocytic anemia and leucopenia were recorded in camels with rickettsioses. The molecular characterization of Rickettsia detected in camels and their tick vectors will help in a better understanding of the epidemiological approach of rickettsioses in Egypt.