Risk of tick-borne zoonoses in urban green areas: A case study from Turin, northwestern Italy

Ticks are increasingly reported in urban and peri-urban areas, such as city parks or peri-urban forests, acrossEurope. Land use changes, like the transformation of natural ecosystems into residential or recreational areas,and the restoration of natural areas connectivity for biodiversity purposes, facilitate human contact with thesevectors. We evaluated the infestation by Ixodid ticks and their infection by zoonotic agents in two natural reserves (La Mandria and Stupinigi) in the urban area of Turin, northwestern Italy, near to densely inhabitedsuburbs and consistently frequented by people. We monthly performed dragging in 15 sites during a three-yearperiod (2012–2014). 
Over 4000 ticks were collected, belonging to the species: Ixodes ricinus, I. acuminatus, Dermacentor marginatus,D. reticulatus, and Haemaphysalis concinna. The tick burden in La Mandria, a park very rich in wildlife, was higherthan in Stupinigi, which is surrounded by a grid of roads and cultivated fields. The occurrence of I. ricinusnymphs was mainly related to habitat diversity and seasonal variation but weakly influenced by wildlife presence. Conversely, the density of I. ricinus nymphs were effectively estimated by vegetation coverage, microclimatic conditions, and the presence of large wildlife. Molecular analyses showed the infections by Borreliaburgdorferi s.l. (24.1 %), Anaplasma phagocytophilum (2.9 %), and Spotted Fever Group rickettsiae (30.4 %) inI. ricinus. Tick-borne encephalitis virus, that is considered so far absent in northwestern Italy, was not detected. InLa Mandria, the risk of encountering one I. ricinus nymph infected by Borrelia burgorferi s.l. in 100 m2 was 59.1 %(95% Confidence Interval [CI]: 36.3–83.0), and 71.3 % (95%CI: 44.5–93.0) for Rickettsia spp. 
Educational programs on personal protection and surveillance on tick-borne diseases should be enhanced toface the threat posed by tick vectors in green urban landscapes.