A semi-quantitative framework to prioritize the zoonotic risks of invasive alien species
This study introduces a semi-quantitative framework that integrates epidemiological and spatial data to prioritize zoonotic risks from invasive mammals in Europe, revealing that most assessed species pose a major human health impact and highlighting the need for targeted management under a One Health perspective.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer
Wildlife and humans have always shared the same world, but when animals move into new territories where they do not naturally belong, the balance can shift in dangerous ways. These non-native animals, known as invasive species, are often studied for how they disrupt local ecosystems or damage crops. However, a growing concern is their ability to carry diseases that can jump from animals to people. This possibility is not just a theoretical risk; many new infectious diseases that have emerged in recent decades originated in wildlife. When an invasive animal enters a region, it can bring along pathogens it carries without getting sick itself, acting as a hidden reservoir for viruses, bacteria, or parasites. If these animals live close to human populations, the chances of a disease spilling over increase. This is especially true for mammals, which are biologically similar enough to humans that they can sometimes transmit infections more easily. As climate change and land use alter where animals can live, these interactions are becoming more frequent, making it vital to understand which invasive animals pose the greatest threat to human health.
A team of researchers set out to create a practical way to sort through the many invasive mammals in Europe and identify which ones require the most urgent attention regarding disease risk. Instead of relying on vague descriptions, they built a scoring system that combines four specific pieces of information: how common the diseases are within the animal populations, how severe those diseases are for humans, how much of the European landscape the animals can live in, and how many people live in those same areas. The severity of a disease was judged by the level of safety precautions scientists must take to handle the germ in a lab, a standard measure that indicates how dangerous the pathogen is. The researchers applied this system to eight specific mammals that are already regulated by the European Union because they are considered invasive. These animals include the coypu, the raccoon dog, the raccoon, the American gray squirrel, the Siberian chipmunk, the muskrat, the coati, and the small Asian mongoose.
The results of this assessment revealed a clear hierarchy of risk. Six of the eight species were found to have a major potential impact on human health. The raccoon dog and the muskrat received the highest scores, followed closely by the coypu. These animals were flagged as high-risk not just because they carry many different types of germs, but because they are widespread across Europe and live in areas where large numbers of people reside. The coati was rated as having a moderate impact, while the small Asian mongoose was considered to have a minor impact. None of the species fell into the lowest or highest possible categories of risk. The study showed that the animals causing the most ecological disruption are not always the same ones posing the biggest health threats. For instance, the small Asian mongoose had the maximum standardized EU biodiversity score but a relatively low score for human health risk, while another species had a very high health risk score but was not previously highlighted as a top priority for health reasons in existing reports.
This mismatch suggests that current management strategies, which often focus on protecting nature and the economy, might be missing the full picture of the danger these animals present. The researchers compared their new health scores with existing official assessments and found only partial agreement. While some species were consistently ranked as high-risk across all systems, others were overlooked by traditional methods that do not specifically look at disease transmission. The study also looked at the countries where these animals live. It found that while some nations with high exposure to these mammals are well-prepared to handle health emergencies, others face a combination of high exposure and lower levels of public health readiness. This uneven landscape means that in some places, the potential for a disease outbreak is high, but the systems to detect and stop it are not yet strong enough.
The framework developed in this study offers a clear, repeatable way to identify which invasive species and which regions need more focus. By bringing together data on where animals live, how many people they live near, and what diseases they carry, the researchers have provided a tool that helps public health officials and conservation managers work together. This approach supports a "One Health" perspective, which recognizes that the health of people, animals, and the environment are deeply connected. Rather than waiting for an outbreak to happen, this method allows authorities to prioritize prevention and early detection for the species that pose the greatest threat. The study does not claim to solve the problem of zoonotic diseases, but it provides a solid, evidence-based starting point for making smarter decisions about how to manage invasive species in a way that protects human health.
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