Dermacentor marginatus and Dermacentor reticulatus, and Their Infection by SFG Rickettsiae and Francisella-Like Endosymbionts, in Mountain and Periurban Habitats of Northwestern Italy

Abstract

We investigated the distribution of Dermacentor spp. and their infection by zoonotic bacteria causing SENLAT (scalp eschar neck lymphadenopathy) in Turin province, northwestern Italy. We collected ticks in a mountain and in a periurban park, from vegetation and different animal sources, and we sampled tissues from wild boar. Dermacentor marginatus (n = 121) was collected in both study areas, on vegetation, humans, and animals, while D. reticulatus (n = 13) was exclusively collected on wild boar from the periurban area. Rickettsia slovaca and Candidatus Rickettsia rioja infected 53.1% of the ticks, and R. slovaca was also identified in 11.3% of wild boar tissues. Bartonella spp. and Francisella tularensis were not detected, however, Francisella-like endosymbionts infected both tick species (9.2%). Our findings provide new insights on the current distribution of Dermacentor spp. and their infection with a spotted-fever group rickettsiae in the Alps region. Wild boar seem to play a major role in their eco-epidemiology and dispersion in the study area. Although further studies are needed to assess the burden of rickettsial diseases, our results highlight the risk of contracting SENLAT infection through Dermacentor spp. bites in the region.

Rickettsiales in Italy

“…Dermacentor ticks infected with the above rickettsiae were found prevalently in Tyrrhenian coast and western alps and have a period of activity cold season (from late fall to mid spring [ 186 ]). The tick species found infected were D. reticulatus [ 89 ] and D. marginatus [ 32 , 34 , 40 , 42 , 43 , 45 , 46 , 51 , 61 , 72 , 80 , 83 , 84 , 85 , 86 , 87 , 88 , 90 , 92 ], the first was found only once in the western alps on a wild boar, the second was more commonly found. Other ticks involved in ecology of R. slovaca are Ha.…”

“…R. raoultii [ 46 , 51 , 61 , 72 , 83 , 84 , 85 , 86 , 87 ] and R. rioja [ 88 ], were both found in Italy in D. marginatus and, R. raoultii in other ticks like Ixodes spp. [ 48 , 52 , 62 ], Rhipicephalus spp.…”

“…Strain S [ 40 ], R. sp. strainTwKm01 [ 53 ], Candidatus R. barbariae [ 32 , 43 , 47 ], Candidatus R. siciliensis [ 89 ], Candidatus R. mendelii [ 74 ], R. honei [ 40 ], R. tamurae [ 42 ], R. rioja [ 88 ], R. limoniae [ 70 ], R. raoultii [ 41 , 46 , 48 , 51 , 52 , 61 , 62 , 72 , 83 , 84 , 85 , 86 , 87 ]. R. belli , interestingly, was identified in Crataerina pallida , an Hippoboscidae hematophagous dipter [ 54 ].…”

Detection of Rickettsia raoultii in Dermacentor reticulatus and Haemaphysalis inermis ticks in Slovakia

“…The diversity of pathogens in ecosystems also depends on the species diversity of vectors and hosts and the diversity of habitats (de la Fuente et al 2008). Many ticks in Europe, including Dermacentor reticulatus Fabricius, 1794 are known to act as carriers, reservoirs and/or vectors of different pathogenic Rickettsia species e.g., Rickettsia slovaca (Sekeyová et al 1998;Garcia-Vozmediano et al 2020) and Rickettsia raoultii (Boldiš et al 2008;Földvári et al 2013).…”

Low Risk Perception about Ticks and Tick-Borne Diseases in an Area Recently Invaded by Ticks in Northwestern Italy

“…This phenomenon may be linked to several factors, such as changes in land-use practices and spontaneous reforestation, increased abundance of wild ungulate populations, and the milder temperatures that mountain areas are experiencing due to climatic changes. In Piedmont, ticks were deemed rare until the early 2000s, while they now can be found on vegetation, up to approximately 1700 m above sea level [ 10 , 11 ]. Ixodes ricinus is the prevalent tick species, and it can harbor different zoonotic bacteria, including Borrelia burgdorferi s.l.…”