# Single and Co-Infections by Tick-Borne Pathogens in Synanthropic European Hedgehogs (Erinaceus europaeus) in Northwestern Italy

## TL;DR

European hedgehogs in urban areas can carry tick- and flea-borne pathogens, posing a zoonotic disease risk to humans and pets.

## Contribution

First report of a flea-borne Rickettsia related to R. asembonensis in European hedgehogs and evidence of skin as a key site for pathogen detection.

## Key findings

- Anaplasma phagocytophilum, Borrelia burgdorferi s.l., and Rickettsia spp. were detected in European hedgehog skin and ticks.
- A flea-borne Rickettsia closely related to R. asembonensis was identified for the first time in European hedgehogs.
- Pathogens showed skin tropism and interactions, with A. phagocytophilum and B. burgdorferi s.l. excluding Rickettsia spp.

## Abstract

The rapid increase in wildlife species adapted to urban environments may contribute to the maintenance of zoonotic pathogens in cities, thereby increasing infection risk for urban residents and domestic animals. The European hedgehog (Erinaceous europaeus) is one of these widespread synantropic mammals and is frequently infested with ticks and fleas that act as vectors for zoonotic pathogens. We examined fleas, ticks, skin and spleen samples from 129 European hedgehogs admitted to two wildlife rescue centers in northwestern Italy to assess their role in maintaining pathogenic bacteria. We detected Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato, B. myiamotoi and a flea-borne Rickettsia closely related to the zoonotic R. asembonensis, reported here for the first time in European hedgehogs. All bacteria were found more often in skin than in spleen, where A. phagocytophilum and B. burgdorferi s.l. tended to occur together while both appeared to exclude the presence of Rickettsia spp. These results indicate that hedgehogs can harbor vector-borne pathogens and highlight the importance of considering urban wildlife in surveillance and control programs for diseases transmitted by ticks and fleas.

Tick-borne pathogens (TBPs) are increasingly recorded in urban areas, where synanthropic wildlife may sustain pathogen transmission cycles. The European hedgehog (Erinaceus europaeus), frequently infested with ectoparasites, may serve as an urban reservoir of zoonotic TBPs. We investigated TBPs in host tissues and associated ectoparasites (Ixodes spp. and Archaeopsylla erinacei) from 129 hedgehogs in northwestern Italy. Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato and Rickettsia spp. were detected in skin, spleen and ectoparasites (Ixodes spp. and Archaeopsylla erinacei). One spleen sample was positive for B. miyamotoi. Molecular identification revealed A. phagocytophilum ecotype 1, B. afzelii and B. bavariensis. A flea-borne Rickettsia closely related to the zoonotic Rickettsia asembonensis was identified for the first time in European hedgehogs. All pathogens were more prevalent in skin than in spleen. In skin, A. phagocytophilum and B. burgdorferi s.l. showed a positive interaction, whereas both were negatively associated with Rickettsia spp. These findings highlight hedgehogs as potential urban reservoirs of zoonotic TBPs, posing a potential risk for humans and domestic animals. The marked skin tropism of these pathogens supports the use of skin for TBP surveillance and underlines its role as a key interface for vector-borne transmission.