European hedgehogs: evaluation of human-animal interactions in an urban environment

The European hedgehog (Erinaceus europaeus) is a nocturnal, insectivorous mammal native to western and central Europe. In recent decades, it has shifted from rural to urban areas, becoming a synanthropic species. Urban environments offer more shelter and food, but also expose hedgehogs to significant risks such as habitat fragmentation and injuries from traffic and pets, which seem to contribute to the population decline observed across many European countries. On the other hand, urban hedgehogs may also act as reservoirs for zoonotic pathogens and their vectors (e.g., ticks and fleas), potentially facilitating pathogen transmission to humans and domestic animals. Wildlife rescue centres (WRCs), where diseased hedgehogs receive care, represent a critical interface for human-animal interactions. In WRCs, hedgehogs are exposed to altered diets, contact with other species, and medical treatments, promoting antimicrobial resistance (AMR) acquisition and potentially influencing gut microbiota composition. This PhD project investigates human-hedgehog interactions in urban contexts, focusing on four aspects: 1. Human impact on mortality: necropsies and histopathological examinations were performed on 271 hedgehogs (162 from two WRCs in north-western Italy and 109 from the Zurich area - Switzerland). Infectious diseases were the leading causes of death (60.5%), followed by trauma (27.7%), often linked to human activity. 2. Zoonotic pathogen carriage: tissue and ectoparasite samples were analysed using molecular techniques. Among zoonotic agents, hedgehogs mainly carried Anaplasma phagocytophilum (8.3% in the skin, 4.5% in the spleen), Bartonella spp. (22.7% in the spleen), Borrelia burgdorferi (9.1% in the skin, 1.5% in the spleen), Leptospira spp. (22.0% in the kidneys), and Rickettsia spp. (66.7% in the skin, 3.8% in the spleen). No major differences were observed between urban and rural individuals, suggesting that hedgehogs contribute to pathogen persistence not only in natural environments but also in cities. 3. Antimicrobial resistance in WRCs: commensal Escherichia coli isolates from rectal swabs were analysed before and after 10 days of hospitalisation. Resistant strains were 2 already present upon arrival, and hospitalisation promoted further resistance, especially to doxycycline, enrofloxacin, and trimethoprim-sulfamethoxazole, including an increase in extended-spectrum beta-lactamase-producing E. coli. 4. Gut microbiota alterations in WRCs: intestinal microbiota was sampled through rectal swabs from adult hedgehogs at admission to WRCs and after 10 days of hospitalisation. 16S rRNA sequencing revealed that the habitat of origin did not significantly affect hedgehog gut microbiota diversity, whereas hospitalisation resulted in marked changes in both alpha and beta diversity. This multidisciplinary research highlights how urban environments shape hedgehog ecology and health and underlines the role of this mammal in One Health dynamics, offering insight for public health and conservation strategies.