Tick-Borne Zoonoses in Northern Portugal: Molecular Screening of Ixodid Ticks from Wild Mammals

Resumo

Objectives: Ixodid ticks are globally distributed hematophagous arthropods, known vectors of several pathogens that threaten both animal and human health. Wild mammals may act as reservoirs for tick-borne pathogens such as Ehrlichia spp., Anaplasma spp., and Borrelia spp., contributing to their persistence in natural ecosystems. This study aimed to characterize ixodid tick infestation in wild mammals admitted to a Wildlife Rehabilitation Centre in northern mainland Portugal and to screen collected ticks for Borrelia, Anaplasma, and Ehrlichia species.
Materials and Methods: Ticks were collected from wild mammals admitted to the Centre and identified morphologically to the species level using stereomicroscopy and taxonomic keys. A representative subset of ticks was screened by PCR for Anaplasma/Ehrlichia spp. and Borrelia spp., targeting the 16S rRNA and flaB genes, respectively. Positive amplicons were sequenced and analyzed using BLAST and phylogenetic methods for species identification.
Results: A total of 374 ticks were collected from 51 hosts of six different species of wild mammals. The tick species identified included 51 Ixodes ricinus (62% adults), 23 Ixodes hexagonus (52% adults), 280 Rhipicephalus sanguineus (85% adults), 1 adult Rhipicephalus pusillus, 11 Rhipicephalus spp. (73% larvae) and 7 nymphs and 1 larva of unidentified species. A total of 24 ticks from the species I. ricinus (n=4), R. sanguineus (n=19) and Rhipicephalus spp. (n=1) yielded PCR amplicons consistent with Borrelia spp., while 7 ticks from R. sanguineus (n=6) and I. ricinus (n=1) generated amplicons compatible with Anaplasma/Ehrlichia spp. For one Borrelia spp. sample, the phylogenetic tree revealed that the sequence clustered in a monophyletic group supported by 100% bootstrap, along with reference sequences of Borrelia garinii. The B. garinii DNA was detected in a R. sanguineus tick collected from a Genetta genetta.
Conclusions: These findings confirm the presence of Borrelia, Anaplasma, and Ehrlichia spp. in ticks from wild mammals in northern Portugal. The detection of the zoonotic B. garinii highlights the potential role of wild mammals as reservoirs, emphasizing the importance of integrated tick-borne pathogen surveillance within a One Health framework.
Keywords: Anaplasma, Borrelia garinii, Ehrlichia, ixodid ticks, wild mammals, Polymerase Chain Reaction, molecular epidemiology
Funding: Project funded by Lusófona University. (FMV_Estágios_23-24)