Tick-borne Rickettsiales: Molecular tools for the study of an emergent group of pathogens

Guillemi, Eliana Carolina; Tomassone, Laura; Farber, Marisa Diana

doi:10.1016/j.mimet.2015.10.009

Cited by 24 publications

(20 citation statements)

References 133 publications

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“…While, hemolymph staining was successful as a field test for detection of Rickettsia in ticks which kept ticks undamaged, so that the infected ticks can be used in other purposes (Gimenez, 1964). However, the susceptibility of the Gimenez stain to other bacterial agents than Rickettsia justified the magnified prevalence percentage of infection in ticks by staining technique and needed to be confirmed by PCR; the more specific technique (Parola et al, 2013;Guillemi et al 2015).…”

Section: Discussionmentioning

confidence: 99%

“…Here, PCR technique was carried out on 61 camels' blood samples and their ticks using OmpA and gltA genes; SFP specific primers (Parola et al, 2013;Guillemi et al, 2015). The results revealed that twenty-five camels, from Cairo, Giza and Sinai provinces and one tick (H. marginatum) from Sinai province, were positive for Rickettsia spp.…”

Section: Discussionmentioning

confidence: 99%

“…Molecular techniques were applied targeting accurate and rapid detection and identification of Rickettsia spp. PCR followed by sequencing improved the sensitivity of diagnosis and specificity of taxonomy (Parola et al, 2013;Guillemi et al, 2015). Primers amplifying the OmpA and gltA genes were less conserved genes, so it had a higher discriminating power between genomes of SPG Rickettsia spp.…”

Section: Introductionmentioning

confidence: 99%

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Molecular Diagnosis of Rickettsiae Infecting Camels and Ixodid Ticks in Egypt

Abdullah¹,

El-Molla²,

Salib³

et al. 2019

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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.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Molecular Diagnosis of Rickettsiae Infecting Camels and Ixodid Ticks in Egypt

Abdullah¹,

El-Molla²,

Salib³

et al. 2019

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“…These two genes have high discrimination power to detection of Rickettsia spp. due to high variability within SFG [23,27]. …”

Section: Introductionmentioning

confidence: 99%

Morphological and molecular identification of the brown dog tick Rhipicephalus sanguineus and the camel tick Hyalomma dromedarii (Acari: Ixodidae) vectors of Rickettsioses in Egypt

Abdullah¹,

El-Molla²,

Salib³

et al. 2016

Vet World

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Aim:Rickettsioses have an epidemiological importance that includes pathogens, vectors, and hosts. The dog tick Rhipicephalus sanguineus and the camel tick Hyalomma dromedarii play important roles as vectors and reservoirs of Rickettsiae. The aim of this study was to determine the prevalence of Rickettsiae in ixodid ticks species infesting dogs and camels in Egypt, in addition to, the morphological and molecular identification of R. sanguineus and H. dromedarii.Materials and Methods:A total of 601 and 104 of ticks’ specimens were collected from dogs and camels, respectively, in Cairo, Giza and Sinai provinces. Hemolymph staining technique and OmpA and gltA genes amplification were performed to estimate the prevalence rate of Rickettsiae in ticks. For morphological identification of tick species, light microscope (LM) and scanning electron microscope (SEM) were used. In addition to the phylogenetic analyses of 18S rDNA, Second internal transcript spacer, 12S rDNA, cytochrome c oxidase subunit-1, and 16S rDNA were performed for molecular identification of two tick species.Results:The prevalence rate of Rickettsiae in ticks was 11.6% using hemolymph staining technique and 6.17% by OmpA and gltA genes amplification. Morphological identification revealed that 100% of dogs were infested by R. sanguineus while 91.9% of camels had been infested by H. dromedarii. The phylogenetic analyses of five DNA markers confirmed morphological identification by LM and SEM. The two tick species sequences analyses proved 96-100% sequences identities when compared with the reference data in Genbank records.Conclusion: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 to, the detection of Rickettsiae in both ticks’ species and establishment of the phylogenetic status of R. sanguineus and H. dromedarii would be useful in understanding the epidemiology of ticks and tick borne rickettsioses in Egypt.

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“…The diagnosis of rickettsiae was characterized as a challenge, because of nonspecific clinical signs and laboratory abnormalities or subclinical infection [9,17,25]. Molecular techniques (including PCR and sequencing) were applied to allow more accurate and rapid detection and identification of rickettsiae with improved sensitivity and specificity of the diagnosis [17,34].…”

Section: Discussionmentioning

confidence: 99%