A molecular survey of spotted fever group rickettsiae in introduced raccoons (Procyon lotor)

Abstract

Background The raccoon Procyon lotor (Linnaeus, 1758) (Carnivora; Procyonidae) is one of the most important and most intensively studied invasive mammal species in Europe. Within the last 30 years the raccoon has spread at an increasing rate, resulting in the establishment of local populations in various regions of Europe. In these newly colonised areas, gaps in knowledge of the raccoon’s biology concern not only most aspects of its ecology in a broad sense, but also its pathogens and parasites. Most micropathogens recorded hitherto in the raccoons that have colonised Europe have documented epizootic and zoonotic potential. Thus, it is considered especially important to investigate the role played by the raccoon in the spread of pathogens through both animal-animal and animal-human pathways. Methods Tissue samples of raccoons from Poland and Germany were examined in this study. In total, 384 tissue samples from 220 raccoons (170 spleen samples, 82 liver biopsies, 132 ear biopsies) were examined using molecular methods. The presence of Rickettsia spp. DNA was screened through amplification of a fragment of the gltA gene. Samples that were PCR positive for gltA were tested for other rickettsial genes, ompB and a 17-kDa antigen. For taxonomic purposes, the obtained sequences were compared with corresponding sequences deposited in GenBank using the Basic Local Alignment Search Tool, and phylogenetic analyses were conducted using Bayesian inference implemented in MrBayes software. Results Rickettsia DNA was confirmed only in skin biopsies; no isolates from the spleen or liver were positive for Rickettsia DNA. With the exception of one sample from Germany, which was positive for Rickettsia helvetica DNA, all the samples positive for Rickettsia DNA derived from the Polish population of raccoons. DNA of Rickettsia spp. was detected in 25 samples, i.e. 11.4% of the tested raccoons, and R. helvetica was confirmed in 52% of the positive samples. Additionally, single cases of Rickettsia monacensis, Rickettsia raoultii, and Candidatus Rickettsia kotlanii-like were found, and in 32% of all the positive samples similarity was shown to different Rickettsia endosymbionts. Out of the samples that tested positive for gltA, amplicons of ompB and 17 kDa were successfully sequenced from 14 and three samples, respectively. Conclusions To the best of our knowledge, this study provides, for the first time, evidence of the occurrence of Rickettsia pathogens and endosymbionts in the European population of raccoons. Further, broader research on different species of wild vertebrates, and ticks, as potential vectors and hosts for tick-borne pathogens, in natural as well as in peri-urban environments, is therefore required. Graphical abstract

Occurrence of Dirofilaria repens in wild carnivores in Poland

“…Raccoons and raccoon dogs have shown low prevalence for helminths and blood parasites in Poland (Popiołek et al 2011 ; Hildebrand et al 2022 , 2022 ). To the best of our knowledge, D. repens has not yet been recorded in these two species.…”

“…A total of 511 blood and spleen samples were collected between 2016 and 2022 from seven animal species (287 red foxes, 62 grey wolves, 54 Eurasian badgers, 58 raccoons, 35 raccoon dogs, 8 stone martens, and 7 pine martens). Samples were collected from carcasses obtained by the authors from hunters during hunting seasons (Dwużnik et al 2020 ; Hildebrand et al 2022 , 2022 ), from animals killed or injured in car accidents, and individuals captured for telemetry studies or found dead from unknown reasons in the forests, roads, and fields (Szewczyk et al 2019 ).…”

“…A significant number of samples originated from the Bory Dolnośląskie Forest in Lower Silesia voivodeship in the Silesian region. From this region, carcasses were provided by licensed hunters during the autumn/winter hunting seasons or in the course of the Life Project LIFE11 NAT/PL/428 “Active protection of lowland populations of capercaillie ( Tetrao urogallus ) in the Bory Dolnośląskie Forest and Augustowska Primeval Forest.” Raccoons were shot in Western Poland (Lower Silesia) as the part of a control program of invasive species Hildebrand et al 2022 , 2022 ).…”

“…This lack of studies is partly due to the difficulty of collecting fresh blood samples from free-living animals or their corpses but especially because some of these animals are protected species (e.g., grey wolves). However, raccoons and raccoon dogs are known to be invasive species in Europe including Western Poland and are competent hosts for a range of blood and intestinal parasites (Myśliwy et al 2022 ; Hildebrand et al 2022 , 2022 ). Hence, their spread to new regions in Europe may facilitate the spread of parasites for which they constitute competent hosts.…”

Occurrence of Borrelia sp. among Wild Living Invasive and Native Mesocarnivores in Poland

“…The animals were sampled in the Ruszów Forest District (Poland), in the west part of the Lower Silesian Wilderness, being the largest lowland forest complex in Europe and the unique location of co-occurrence of the native and invasive carnivore species in Europe. The tissue samples obtained through collaboration with other projects were collected mainly during a predator control operation carried out as a part of the capercaillie ( Tetrao urogallus ) reintroduction program in the Lower Silesian Forest [ 17 , 18 ]. The tissue samples were delivered to the laboratory of the Department of Parasitology, University of Wrocław, and stored at −20 °C.…”