y growing specialist literature cannot possibly be surveyed by individuals.
At the same time, we are observing, especially using the example of COVID-19, how complex the relationships and dependencies between people, animals and the environment are. How can we move in the direction of a modern theory of health suited to face the new complex challenges of global change? Health must be viewed as the sphere of influence of human actions within human-environment systems or ecosystems approaches to health. We also speak of “health in social-ecological systems” (see Box below).
Health concepts at a glance
One Health is, in the first place, at the intersection of human and animal health, aiming to demonstrate a benefit from a closer cooperation of human and veterinary medicine. Clearly, large sections of separated human and animal health do not require a One Health approach. Broader approaches, considering interactions of health and the environment, within social-ecological systems (SES) comprehend One Health, which is thus embedded within ecosystem approaches to health (EcoHealth), for which a newer term, “Health in Social-Ecological Systems” (HSES), has been coined. SES are most often delimited by a given context of a country or a region. One Health includes social and environmental (ecological) factors, reaching beyond the strict limits of public and animal health.
Planetary Health conceptual thinking aims to identify co-benefits across targets, but remains centred on human health and does not explicitly include animal health. Planetary Health can be seen as a historical extension from global health and international health. It attempts to demonstrate linkages of global environmental change and health, which are hard to prove, based on the inherent data variability, confounding factors, and the duration and scale of the phenomena. We argue that One Health should still be at the centre of interest, building inter-sectoral cooperation from the inside and gradually expanding it to more complex issues and health security hazards across the whole of the SES, as the evidence base for its effectiveness matures.
This perspective includes scaling of systems biology aspects from the molecular and cellular level up to human and animal populations, which helps us understand health explicitly as a consequence of processes in complex human-environment systems. This also includes unpredictable, emergent phenomena (emerging diseases) in the sense of Alfred North Whitehead’s process philosophy. For example determining the origin of the current COVID-19 pandemic to be able to prevent such outbreaks in the future (see Box below).
Why transdisciplinary approaches are needed – the example of COVID-19
The importance of transdisciplinary approaches can be shown well using the example of the COVID-19 outbreak. Epidemiologists and virologists claim the scientific authority to interpret the current pandemic, but not to recommend how society should deal with it. Governments and scientists cannot solve this dilemma on their own. All actors have interests they are pursuing, so a social consensus can best be achieved through a participatory (transdisciplinary) process including representatives of all interest groups.
Most of the Corona viruses have been found in wildlife and livestock. Only few Corona viruses have adapted to humans. Some of the animal viruses in cattle, dogs and humans are genetically close to SARS-CoV-2, the virus causing COVID-19. It is possible that the exposure to animals carrying Corona viruses may elicit a cross-protection against COVID-19 infection and the severity of the clinical course. More research is needed to elucidate possible cross-protection between human and animal Corona viruses.
From a One Health perspective, human, domestic animal and wildlife disease surveillance should be integrated and closely communicated. Integrated surveillance-response systems show that the earlier a zoonotic agent is detected in the environment, in wild animals or domestic animals, and the better the monitoring data for humans, animals and the