Abstract
To obtain a better understanding of the current magnitude of tick-borne rickettsioses in Corsica, we used molecular methods to characterize the occurrence of Rickettsia spp. in ixodid ticks collected from domestic and wild animals. The presence of Rickettsia spp. was evaluated using real-time polymerase chain reaction targeting the gltA gene and by sequencing of gltA and ompA partial genes for species identification and phylogenetic analysis. Infection rates were calculated as the maximum-likelihood estimation (MLE) with 95% confidence intervals (CI). In total, 1117 ticks belonging to four genera (Rhipicephalus, Hyalomma, Ixodes, and Dermacentor) were collected from cattle, sheep, wild boars, and companion animals during July–August 2017 and July 2018–January 2019. Overall, Rickettsia DNA was detected in 208 of 349 pools of ticks (MLE = 25.6%, 95% CI: 22.6–28.8%). The molecular analysis revealed five different rickettsial species of the spotted-fever group (SFG). We highlighted the exclusive detection of Candidatus Ri. barbariae in R. bursa and of Ri. aeschlimanii in H. marginatum. Rickettsia slovaca was detected in D. marginatus collected from wild boars. This study provides the first evidence of the presence of Ri. monacensis in I. ricinus ticks isolated from a dog in Corsica. In conclusion, our data revealed wide dispersal of SFG Rickettsiae and their arthropod hosts in Corsica, highlighting the need for surveillance of the risk of infection for people living and/or working close to infected or infested animals.
Highlights
Rickettsiae are obligate intracellular Gram-negative bacteria that are transmitted to vertebrate hosts by arthropod vectors such as ticks, fleas, lice, and mites
The sequences of mitochondrial 16S rDNA fragments of 12 ticks selected in this study, were confirmed, after BLAST analysis, to be D. marginatus (n = 5), R. bursa (n = 1), H. marginatum (n = 1), I. ricinus (n = 1), and R. sanguineus s.l. (n = 4)
This study reports the first evidence of the circulation of five species of the Rickettsia genus in Corsican ticks representing four genera, namely, Rhipicephalus, Hyalomma, Dermacentor, and Ixodes, that were collected from wild and domestic animals
Summary
Rickettsiae are obligate intracellular Gram-negative bacteria that are transmitted to vertebrate hosts by arthropod vectors such as ticks, fleas, lice, and mites. The genus Rickettsia (family Rickettsiaceae; order Rickettsiales) comprises 31 species that cause diseases in vertebrate hosts, including humans and domestic and wild animals [1]. Ticks can transmit these bacteria to humans and animals by feeding. The SFG and AG Rickettsiae are mainly associated with ticks, while TG and TRG Rickettsiae are associated with other arthropods such as lice, fleas, and mites [3]. In the Pathogens 2019, 8, 138; doi:10.3390/pathogens8030138 www.mdpi.com/journal/pathogens
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