A one-health approach to surveillance of tick-borne pathogens across different host groups

Tick-borne pathogens are increasingly impacting wildlife and human populations' health due to expanded vector ranges and the growing popularity of outdoor activities. This study aimed to survey the prevalence of tick-borne zoonotic (TBZ) microorganisms in a rural area, targeting different host groups involved in their circulation, namely wildlife, domestic animals, humans and questing ticks, addressing the risk associated to hunting and outdoor leisure activities in an alpine environment. The study was performed in an alpine district in Northwestern Italy. We collected 124 pools of questing ticks using dragging transects across 38 locations distributed in the district. In addition, we obtained 133 spleen samples from game ungulate species (wild boar, red deer, and chamois), 67 blood samples from volunteer rural inhabitants, and samples from 38 privately-owned hunting dogs. All samples were tested by PCR for Babesia divergens/B. capreoli, B. microti-like, B. venatorum, Borrelia burgdorferi sensu latu, Rickettsiae Spotted Fever Group (SFG) and Anaplasma phagocytophilum. All investigated pathogens, except B. burgdorferi s.l. (found only in questing ticks), were detected in rural inhabitants. Babesia divergens/B. capreoli and B. venatorum were highly prevalent in wild ruminants, while B. microti-like organisms appeared sporadically in wild boar and dogs. SFG Rickettsiae were most common in dogs, with occasional cases in wild boar. Anaplasma phagocytophilum showed low prevalence in ticks and wildlife, but higher detection rates in humans and dogs. Our results underscore the interconnected nature of tick-host dynamics in the spread of TBZ and highlight the need for an expanded surveillance approach, potentially including other significant reservoirs.