Acarological risk of exposure to tick-borne pathogens in urban green areas of Rome, Italy

Acarological risk (R) was assessed in urban green areas of Rome. R was calculated as the probability of encountering at least one questing tick infected by spotted fever group (SFG) rickettsiae, Borrelia burgdorferi sensu lato and/or Coxiella burnetii, in 100 m transects within paths commonly walked by park-goers. Seasonal dynamics of Ixodes ricinus, Rhipicephalus bursa and Rhipicephalus turanicus were analysed together with their infection prevalence. Targeted PCR protocols were carried out to detect Rickettsia species, and highlight the presence of C. burnetii, B. burgdorferi s.l. and Piroplasmida. A total of 93 ticks were collected: 65 by dragging and 28 on animals. Twenty-four ticks (25.8 %) were found infected by SFG rickettsiae, while no ticks tested positive for other zoonotic pathogens. Rickettsia massiliae was found in questing Rhipicephalus sanguineus s.l. and R. turanicus; Rickettsia monacensis was associated with I. ricinus and Rickettsia aeschlimannii with Hyalomma marginatum. R calculated on questing ticks peaked in April (R = 0.078, CI_{95 %} = 0.073-0.082) and September (R = 0.050, CI_{95 %} = 0.048-0.053) and showed the highest value (0.073) in a park near Rome city centre (∼2 km from the Vatican City State). Ixodes ricinus and R. turanicus were the most abundant species collected by dragging, displaying a different seasonal dynamic, the former active in spring and early autumn, the latter in summer. Ixodes ricinus showed the highest percentage of positive individuals (25 %). Our results could be useful in prioritizing site-specific interventions in those green areas where higher tick abundance and/or pathogens of public health relevance were identified.