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

Risk perception, together with the adoption of measures to prevent tick bites, may strongly influence human exposure to ticks and transmitted pathogens. We created a questionnaire to evaluate how people perceive the health risk posed by ticks in an area recently invaded by these arthropods, in the western Italian Alps. Moreover, through a collaborative effort with park rangers and physicians, we investigated which tick species bite humans and their infection with pathogens (Borrelia burgdorferi s.l., Anaplasma phagocytophilum, and spotted-fever group Rickettsiae). Apart from two Dermacentor marginatus bites, we identified Ixodes ricinus (n = 124) as the main species responsible for tick bites. The investigated pathogens infected 25.4% of tested I. ricinus. The evaluation of the engorgement rate of biting I. ricinus revealed that they had been likely feeding on humans for 24 h or more, suggesting a high probability of pathogen transmission. Indeed, the questionnaires revealed that people infrequently adopt preventive measures, such as inspecting the body for ticks, although most respondents claimed that ticks are a threat to human health. Having suffered from previous tick bites was positively associated with the adoption of personal protection measures. Given the increasing incidence of tick-borne diseases in the region, the public should be better informed about the possibility of being bitten by infected ticks in order to mitigate the risk.

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

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.

Ticks climb the mountains: Ixodid tick infestation and infection by tick-borne pathogens in the Western Alps.

In mountain areas of northwestern Italy, ticks were rarely collected in the past. In recent years, a marked increase in tick abundance has been observed in several Alpine valleys, together with more frequent reports of Lyme borreliosis. We then carried out a four-year study to assess the distribution and abundance of ticks and transmitted pathogens and determine their altitudinal limit in a natural park area in Piedmont region. Ixodes ricinus and Dermacentor marginatus were collected from both the vegetation and hunted wild ungulates. Tick abundance was significantly associated with altitude, habitat type and signs of animal presence, roe deer's in particular. Ixodes ricinus prevailed in distribution and abundance and, although their numbers decreased with increasing altitude, we recorded the presence of all active life stages of up to around 1700 m a.s.l., with conifers as the second most infested habitat after deciduous woods. Molecular analyses demonstrated the infection of questing I. ricinus nymphs with B. burgdorferi sensu lato (15.5 %), Rickettsia helvetica and R. monacensis (20.7 %), Anaplasma phagocytophilum (1.9 %), Borrelia miyamotoi (0.5 %) and Neoehrlichia mikurensis (0.5 %). One third of the questing D. marginatus were infected with R. slovaca. We observed a spatial aggregation of study sites infested by B. burgdorferi s.l. infected ticks below 1400 m. Borrelia-infected nymphs prevailed in open areas, while SFG rickettsiae prevalence was higher in coniferous and deciduous woods. Interestingly, prevalence of SFG rickettsiae in ticks doubled above 1400 m, and R. helvetica was the only pathogen detected above 1800 m a.s.l. Tick infestation on hunted wild ungulates indicated the persistence of tick activity during winter months and, when compared to past studies, confirmed the recent spread of I. ricinus in the area. Our study provides new insights into the population dynamics of ticks in the Alps and confirms a further expansion of ticks to higher altitudes in Europe. We underline the importance of adopting a multidisciplinary approach in order to develop effective strategies for the surveillance of tick-borne diseases, and inform the public about the hazard posed by ticks, especially in recently invaded areas.