Metallic Trace Elements Associated with Infectious Diseases in European Hedgehogs (Erinaceus europaeus) in Belgium

Wild animals are increasingly exposed to a complex array of environmental stressors, including habitat fragmentation, pollution, and emerging infectious diseases, which can interact in unpredictable ways to influence animal health and survival. The European hedgehog (Erinaceus europaeus), recently classified as near threatened on the IUCN red list, faces many of these challenges. This study investigates the relationships between hepatic concentrations of metallic trace elements (MTEs) and health status in free-ranging Belgian hedgehogs, both juveniles and adults, with a focus on hedgehog diphtheric disease (HDD) and a novel circovirus. We analyzed liver samples for essential (zinc [Zn], copper [Cu]) and nonessential (lead [Pb], cadmium [Cd]) MTEs, comparing levels between healthy and affected individuals. Results showed generally moderate MTE levels (Cd: 2.88±4.27 mg/kg dry weight [dw]; Pb: 1.06±1.34 mg/kg dw; Cu: 31.53±39.01 mg/kg dw; Zn: 365.56±282.10 mg/kg dw) compared with other European populations, with the exception of markedly elevated hepatic Zn concentrations, particularly in adults (576.32±200.20 mg/kg dw). Notably, Zn levels were significantly higher in individuals affected by HDD, across both juvenile (P<0.001) and adult (P<0.01) age classes. Although high environmental Zn exposure may predispose hedgehogs to disease, elevated hepatic Zn could also reflect infection-driven redistribution due to inflammation and host immune responses. These findings align with broader evidence linking altered MTE profiles to disease processes in wildlife and suggest a complex, potentially bidirectional interaction between trace element homeostasis and infectious disease. This study highlights the importance of incorporating MTE dynamics into wildlife health surveillance, and suggests that Zn may serve as a potential indicator and mediator of disease in hedgehogs and other free-ranging species.