Why should conservation biologists consider the interaction between tropical rainforest conservation and human health?

The practice of preserving ecosystems, species, and habitats serves to benefit humans in the future for a variety of reasons: firstly economic, through the ecosystem services we receive from natural resources; secondly environmental stability provided by natural systems such as trees as flood barriers and air purifiers, and the equilibrium of pristine ecosystems maintaining themselves; there’s also benefit to conservation because it brings humans joy to experience nature and its beauty; and if we view ourselves as the caretakers of earth, it is our moral imperative to preserve its health, not for our own benefit, but for the good of all the other organisms which do not have the same autonomy. However, an additional potential benefit to conservation, especially in tropical rainforest habitats, is the possibility to aid human health issues, in an approach called ‘Planetary Health’. This essay will examine the potential for conservation biologists to make positive health changes to the people living in the habitats they aim to protect, thereby protecting the land and its people. I will first lay out the theoretical benefits to this approach, followed by the current progress and case studies, to provide an overview of the health issues associated with conservation strategies.

In 2015, the Rockefeller Foundation and The Lancet medical journal teamed up with the United Nations Framework Convention on Climate Change (UNFCCC) to create a new initiative called the Commission on Planetary Health, which aims to focus on the links between damage to the earth’s natural systems, and damage to human public health. The long-term goal of this initiative, and many other like it, is to integrate conservation and health projects in the tropics, and cooperatively reduce disease and conserve the rainforests.

In the modern world, not only are humans more connected than ever due to globalisation and advancements in technology, but humans are also much closer to our native animals and plants, due to worldwide trends of extensive encroachments on previously wild land. These factors encourage the emergence and spread of zoonotic diseases, such as the current COVID-19 pandemic, as well as others like SARS, Ebola, Zika, HIV, and Nipah virus. As larger populations of humans become more engrained and settled into rainforest habitats, there is an expansion of human-wildlife interface and interaction, which encourages disease transmission, as species that previously never came into contact are now sharing space. If there is a local emergence of a novel contagious zoonotic disease, this is rarely contained, due to large/dense populations, and the prevalence of international travel, therefore spreads to either epidemic or pandemic level. A 2008 study by Jones et al concluded that 75% of new human diseases have animal origins, and the occurrence of these is rising in correlation with the destruction and fragmentation of rainforests. Habitat fragmentation is a huge cause for concern for conservationists, as the increase in ‘edge zones’ means that the regions become more porous to outside factors; for instance, in a rainforest fragmented by logging roads, the surface area of the forest that is now exposed to open, human occupied land is greatly increased, which has a two-way consequence of increasing contact between humans and the forest. Modern modifications to tropical rainforests can be seen as a ‘chronotone’, which is an abrupt change to the natural process of succession, caused by an ecotone, which is an abrupt change in environment (an example of this would be deforestation – where sudden disruption of the natural succession of gap filling interactions that tropical trees go through, is caused by an accelerated and unnatural modification of the space, by the removal of the largest trees).

Prevention of these chronotones would be beneficial for a multitude of reasons, firstly because we predict fewer outbreaks of zoonotic disease, but also because it will benefit the native wildlife, as they will no longer be threatened by culls, to protect human health, and they will be less threatened by human diseases. Instances of these threats have occurred many times: when badgers were named as a possible carrier of Tuberculosis in the UK, as were canines with Rabies, and bats during this current pandemic, have each been met with hostility and culling due to association (no matter how accurate this association may be) with human diseases. Furthermore, it’s known that species such as the endangered mountain gorillas, and many other primates, are extremely vulnerable to contagion from human, or ‘anthroponotic’ diseases, and our common cold can be deadly to whole populations of these valuable creatures.

Additionally, its estimated that 25% of modern medicine was initially discovered/derived from tropical rainforest plants, creating another undeniable link between the maintenance of this habitat and our pharmacological advancements.

Finally, it has been empirically shown that conservation efforts have a higher chance of success if the scientists have the support or cooperation from local people, and one method proven to gain the trust, blessing, and help from them is to incorporate a health care provider into the team. Logging roads often garner support from local native communities because they offer a solution to the remoteness of their location, which often prevents access to healthcare; however, if conservation efforts can offer greater access and reliability of healthcare than the logging companies, this will likely be preferred, and can incentivise local conservation.

Once links have been established between conservation of rainforests, reduced zoonotic diseases, and greater access to healthcare, the momentum towards a planetary health movement can begin. Projects can actively/literally link conservation and human health, by incorporating a health aspect into the arrangement, such as paying for a health centre and local nurse for the region, or bringing rounds of vaccinations or treatments for common illnesses, to generate goodwill within the community, which in turn will benefit the smooth running of conservation efforts. Alternatively, through education, conceptual links can be shown between human health and conservation. For instance, greater understanding of germ theory can display the importance of adequate wastewater management, animal contamination, and personal hygiene, to reduce waterborne diseases.

While there are clear humanitarian reasons for these efforts, which are also extremely valuable, the utility to conservation of acting on human health is significant. There is an obvious disparity between global spending on human health – which totalled $45 billion in 2009 – and spending on environmental issues, which is estimated at ~$3 billion. If we could combine ecological and medical benefits into projects, the source of funding would increase immensely, and would broaden the scope and ambition of conservation projects.

The UNFCCC project previously mentioned has funded and collated hundreds of experiments with a planetary health lens. Livestock-to-human Brucellosis transmission in Mongolia was combated with rounds of sheep and cattle vaccinations, and an agreement to slow the expansion of herd grazed land, which lead to fewer human cases, and less deforestation.

In both SARS and Ebolavirus, tropical bats have been identified as key reservoir and transmission species. Research suggests that regions where rainforest is deeply fragmented have higher infection rates of these diseases, because of increased contact between humans and the carrier species, either indirectly by proximity, or hunting for bushmeat. Reduction of fragmentation, degradation, and encroachment on rainforests, has the potential to limit transmission of these diseases, as well as biological spill-over events of new ones.

A project called Surfaces, integrates the treatment of tropical diseases with the need for mapping and protecting Papua New Guinean rainforests, by creating a team of conservationists and health professionals. While in the Wanang community, scientists combine treating local people (mainly for scabies and other tropical skin conditions), with promoting sustainability in the area.

In a current case, pangolins (which are the most trafficked mammals worldwide), are thought to be the leading reservoir for COVID-19 and were regularly sold at live animal markets across the world, for their scales and meat. China, where COVID-19 is thought to have originated, has recently announced the closure/banning of ‘wet markets’ which sold wild-caught bushmeat, after extensive lobbying from both health and conservation bodies – which will benefit the endangered pangolins, and the humans contracting the disease.

In conclusion, the potential benefits from integrating world health and environmental health are huge. Possible advantages include increased funding, higher probability of successful projects, mutual benefits for researchers and local people, safer environment for native animals, and a greater level of global health justice. Conservation biologists should, and are, considering the interactions between these two scientific fields, and it is becoming increasingly important to view our world as an interconnected organism, with the goal of united planetary health in mind.

Published by amyandkatherine

We are two friends of 12 years, trying to start careers in journalism.

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