Nanopore-based metagenomics reveal a new Rickettsia in Europe.

Accurate identification of tick-borne bacteria, including those associated with rickettsioses, pose significant challenges due to the polymicrobial and polyvectoral nature of the infections. We aimed to carry out a comparative evaluation of a non-targeted metagenomic approach by nanopore sequencing (NS) and commonly used PCR assays amplifying Rickettsia genes in field-collected ticks. The study included a total of 310 ticks, originating from Poland (44.2 %) and Bulgaria (55.8 %). Samples comprised 7 species, the majority of which were Ixodes ricinus (62.9 %), followed by Dermacentor reticulatus (21.2 %). Screening was carried out in 55 pools, using total nucleic acid extractions from individual ticks. NS and ompA/gltA PCRs identified Rickettsia species in 47.3 % and 54.5 % of the pools, respectively. The most frequently detected species were Rickettsia asiatica (27.2 %) and Rickettsia raoultii (21.8 %), followed by Rickettsia monacensis (3.6 %), Rickettsia helvetica (1.8 %), Rickettsia massiliae (1.8 %) and Rickettsia tillamookensis (1.8 %). Phylogeny construction on mutS, uvrD, argS and virB4 sequences and a follow-up deep sequencing further supported R. asiatica identification, documented in Europe for the first time. NS further enabled detection of Anaplasma phagocytophilum (9.1 %), Coxiella burnetii (5.4 %) and Neoehrlichia mikurensis (1.8 %), as well as various endosymbionts of Rickettsia and Coxiella. Co-detection of multiple rickettsial and non-rickettsial bacteria were observed in 16.4 % of the pools with chromosome and plasmid-based contigs. In conclusion, non-targeted metagenomic sequencing was documented as a robust strategy capable of providing a broader view of the tick-borne bacterial pathogen spectrum.

Ticks (Acari: Ixodidae) and Associated Pathoge Collected From Domestic Animals and Vegetation in Stann Creek District, Southeastern Belize, Central America.

Data on the prevalence and distribution of ticks and tick-borne diseases in Belize are lacking. Ticks (n = 564) collected from dogs, horses, and vegetation in two villages in Stann Creek District in southeastern Belize in 2018, were molecularly identified and screened for tick-borne nonviral human pathogens. The identity of 417 ticks was molecularly confirmed by DNA barcoding as Rhipicephalus sanguineus (Latreille) (66.43%), Amblyomma ovale Koch (15.59%), Dermacentor nitens Neumann (11.51%), Amblyomma sp. ADB0528 (3.6%), and the remainder being small records (2.87%) of Amblyomma coelebs Neumann, Amblyomma imitator Kohls, Amblyomma tapirellum Dunn, Amblyomma auricularium Conil, and Amblyomma maculatum Koch. Individual tick extracts were screened for the presence of Rickettsia spp., Babesia spp., Babesia microti, Borrelia spp., Ehrlichia spp., and Anaplasma spp. using available conventional polymerase chain reaction (PCR) assays. Rickettsia parkeri strain Atlantic Rainforest was identified in five specimens of A. ovale, and one other unidentified tick, all collected from dogs. Another unidentified tick-also collected from a dog-tested positive for an undefined but previously detected Ehrlichia sp. With the exception of D. nitens, all eight other tick species identified in this study were collected on dogs, suggesting that dogs could be usefully employed as sentinel animals for tick surveillance in Belize.