Diversity and Phylogeny of Cattle Ixodid Ticks and Associated Spotted Fever Group Rickettsia spp. in Tunisia

Myriam Kratou; Hanene Belkahia; Rachid Selmi; Rihab Andolsi; Mokhtar Dhibi; Moez Mhadhbi; Lilia Messadi; Mourad Ben Said

doi:10.3390/pathogens12040552

Diversity and Phylogeny of Cattle Ixodid Ticks and Associated Spotted Fever Group Rickettsia spp. in Tunisia

Pathogens. 2023 Apr 3;12(4):552. doi: 10.3390/pathogens12040552.

Authors

Myriam Kratou¹, Hanene Belkahia¹, Rachid Selmi^{1

2}, Rihab Andolsi¹, Mokhtar Dhibi³, Moez Mhadhbi³, Lilia Messadi¹, Mourad Ben Said^{1

3

4}

Affiliations

¹ Laboratory of Microbiology, National School of Veterinary Medicine of Sidi Thabet, University of Manouba, Manouba 2010, Tunisia.
² Ministry of National Defense, General Directorate of Military Health, Veterinary Service, Tunis 1008, Tunisia.
³ Laboratory of Parasitology, National School of Veterinary Medicine of Sidi Thabet, University of Manouba, Manouba 2010, Tunisia.
⁴ Department of Basic Sciences, Higher Institute of Biotechnology of Sidi Thabet, University of Manouba, Manouba 2010, Tunisia.

Abstract

Tick-borne rickettsioses are mainly caused by obligate intracellular bacteria belonging to the spotted fever group (SFG) of the Rickettsia genus. So far, the causative agents of SFG rickettsioses have not been detected in cattle ticks from Tunisia. Therefore, the aim of this study was to investigate the diversity and phylogeny of ticks associated with cattle from northern Tunisia and their associated Rickettsia species. Adult ticks (n = 338) were collected from cattle in northern Tunisia. The obtained ticks were identified as Hyalomma excavatum (n = 129), Rhipicephalus sanguineus sensu lato (n = 111), Hyalomma marginatum (n = 84), Hyalomma scupense (n = 12) and Hyalomma rufipes (n = 2). After DNA extraction from the ticks, 83 PCR products based on the mitochondrial 16S rRNA gene were sequenced and a total of four genotypes for Rh. sanguineus s.l., two for Hy. marginatum and Hy. excavatum and only one for Hy. scupense and Hy. rufipes were recorded, with the occurrence of one, two and three novel genotypes, respectively, for Hy. marginatum, Hy. excavatum and Rh. sanguineus s.l. mitochondrial 16S rRNA partial sequences. The tick DNA was tested for the presence of Rickettsia spp. by using PCR measurements and sequencing targeting three different genes (ompB, ompA and gltA). Of the 338 analyzed ticks, 90 (26.6%), including 38 (34.2%) Rh. sanguineus s.l., 26 (20.1%) Hy. excavatum, 25 (29.8%) Hy. marginatum and one (50%) Hy. rufipes tick, were positive for Rickettsia spp. Based on 104 partial sequences of the three analyzed genes, the BLAST analysis and phylogenetic study showed the infection of Hy. excavatum, Hy. marginatum and Rh. sanguineus s.l. tick specimens with R. massiliae, R. aeschlimannii and R. sibirica subsp. mongolitimonae and one Hy. rufipes tick specimen with R. aeschlimannii. In addition, coinfection with R. massiliae and R. aeschlimannii was reported in one Hy. marginatum and one Rh. sanguineus s.l. tick specimen, while a coinfection with R. massiliae and R. sibirica subsp. mongolitimonae was recorded in one Rh. sanguineus s.l. tick specimen. In conclusion, our study reports, for the first time in Tunisia, the infection of cattle ticks belonging to Hyalomma and Rhipicephalus genera with zoonotic Rickettsia species belonging to the SFG group.

Keywords: Rickettsia species; Tunisia; cattle ticks; genotyping; molecular species identification; phylogenetic analysis.

Grants and funding

This work was supported by the research laboratory “Laboratoire d’épidémiologie d’infections enzootiques des herbivores en Tunisie” (LR02AGR03), and the research projects “Screening and Molecular Characterization of Pathogenic and Zoonotic Bacteria of Medical and Economic Interest in Cattle and Camel Ticks in Tunisia” (19PEJC07-22) and “Study of the Bacterial Microbiota in Ticks with a Medical and Economic Impact in Tunisia: Contribution to the Control of Vector-Borne Bacterial Diseases” (P2ES2020-D4P1), all of which were funded by the Ministry of Higher Education and Scientific Research of Tunisia.