The protection of forests plays a key role in protecting human health, from providing nutrition to helping us manage disease.
Infectious diseases that find a home in people have always existed and probably always will. But something about COVID-19 and the rate at which it has spread compared to other outbreaks seems new. While many pathogens are present in wildlife and have been for longer than people generally know, some emergent infectious viruses that have spilled over from animal populations include SARS, MERS, HIV, and many more localized outbreaks of even deadlier diseases such as Nipah and Ebola.
The transmission of disease has changed because of how interconnected people are across the world. The protection and restoration of species habitat, combined with reducing human pressures on wildlife, is a critical step in preventing emergent infectious disease. These actions also have some interesting and positive impacts on two of the more persistent challenges to life on Earth, climate change and global biodiversity loss.
For decades conservation professionals have been working with governments, smallholders, businesses, and each other to protect and restore nature. For some the primary mission is climate change; for others it is food security, saving threatened species, or empowering Indigenous peoples and local communities. Research is starting to demonstrate that this work should also include health professionals and attend to the risk of acute and chronic human health disasters.
We know that the cause and effect between disease and deforestation are far from consistent. The complexity of disease and the complexity of landscapes themselves create a tangled web of opposing and reinforcing interactions. In many places, deforestation or forest degradation increases human risk of malaria or other mosquito-borne diseases. In others, the same conditions that scientists predict would increase disease transmission do not seem to apply.
With a decent amount of evidence to date, it's clear that there are some tangible, verified and lasting connections between human health and the extent and condition of forests. These include at least six outcomes: dietary health, environmental exposure (e.g. air pollution), communicable diseases, hazard risk reductions, mental health, and access to natural compounds or medicinal products.
The protection, conservation, and restoration of forests and their broader landscapes contribute to positive human health outcomes for each of these six components. Forests are often critical in supplying micronutrients through access to wild foods, can mitigate air pollution in some contexts, and can provide the necessary habitat and biodiversity to limit human exposure to and infection by viruses and pathogens present in widespread animal populations. Forests can prevent excessive runoff and reduce ambient temperatures, have a demonstrated ability to help people reduce stress and manage mental health, and are the greatest library of natural compounds with potential and realized medicinal products in the universe.
The conservation and restoration of forests is a necessary component of a future where humanity is better able to manage and cope with the emergence of new infectious diseases. Without landscapes that balance the needs of both nature and people, the world will continue only to react to global health crises instead of preventing them.