A new study from Japan provides further evidence that invasive raccoons (Procyon lotor) can play an important role in the environmental circulation of pathogens with potential implications for human health. Using genomic analyses of bacterial isolates collected from both wild raccoons and river water, researchers from Osaka Metropolitan University identified strong links between invasive raccoon populations and the presence of the emerging zoonotic bacterium Escherichia albertii in freshwater systems.
E. albertii is an emerging food- and waterborne pathogen capable of causing gastrointestinal disease in humans. The bacterium was isolated in more than half of the raccoons examined and in a large proportion of environmental water samples across multiple river systems in Osaka Prefecture. Whole-genome analyses revealed close genetic relationships between strains isolated from raccoons and those detected in river water, suggesting that raccoons may contribute to the contamination of aquatic environments and potentially facilitate pathogen transmission through environmental pathways.
Although the research was conducted in Japan, its findings are highly relevant to Europe. The raccoon is a widely established invasive alien species in several European countries (you can check the distribution of this species using the EASIN search and mapping tool), where populations continue to expand and increasingly interact with urban, agricultural and natural environments. The study highlights how invasive mammals can have a negative impact not only on biodiversity and ecosystem functioning, but also cause epidemic of infectious diseases through complex wildlife -environment - human interactions.
The findings also reinforce the importance of adopting a One Health approach while addressing biological invasions. Monitoring should consider invasive species’ ecological impacts and also their role as reservoirs and vectors of pathogens that may affect wildlife, domestic animals and humans.
In the case of raccoon, species considered of Union concern under EU Regulation 1143/2014, this concern is not limited to E. albertii, since it is known carrier of several zoonotic pathogens, including the roundworm Baylisascaris procyonis, a parasite capable of causing severe neurological disease in humans, currently spreading in Europe. The coexistence of multiple pathogens associated with invasive raccoon populations further underlines the need for integrated surveillance strategies, bridging biodiversity management, veterinary science, environmental monitoring and public health.
Since invasive alien species continue to expand their ranges globally, studies such as this provide valuable evidence that effective management requires collaboration across sectors and disciplines—an essential principle of the One Health approach.
References
Hinenoya, A. et al. (2026). Integrated study on the occurrence and genomic features of Escherichia albertii in environmental water and raccoons in Japan. Applied and Environmental Microbiology. DOI: 10.1128/aem.00076-26.
Magliozzi, C., Artois, M., Bertaccini, A. et al. European primary datasets of alien bacteria and viruses. Sci Data 9, 403 (2022). https://doi.org/10.1038/s41597-022-01485-1