4 links between deforestation and disease

Author: Natalie long
Instagram: @natalielei_

Can deforestation have an effect on disease? Yes, but how?

Today, worldwide, we appear to be witnessing an increase in many zoonotic (from animals) infectious diseases. This could reflect the combined impacts of our rapidly changing demographics, environment, social, technological and other changes in our ways-of-living. One key driver of emergence of dangerous zoonotic disease in humans is linked to changes in the environment as a result of human activity. The COVID-19 outbreak has demonstrated that unsustainable practices, no matter where they occur on the globe, are capable of putting the entire human population’s health at risk. This means that changes in the way we behave within the environment can have a positive impact on the future of human health. Deforestation is a major factor linked to the increased emergence of new zoonotic diseases in human population. There are 4 key reasons for this:

  1. The destruction of habitat as a result of deforestation is giving little option to wildlife but to live closer to human populations. This increases opportunities for animal-human interaction, and as a result this provides more opportunity for a disease to jump. The Ebola outbreak in West Africa is an instance of forest loss which led to closer and more frequent interactions between wildlife and human settlements. A 2017 analysis of the Ebola epidemic in Africa, found that Ebola outbreaks were more likely to occur in areas where forests had recently been cleared. This was because the destruction of the natural habitats of wildlife that carry the disease, pushed them into new areas which were closer to humans where the disease jumped to our population.
  2. Deforestation changes the structure of an ecosystem and new conditions could become favourable to disease. Disease is a natural part of ecosystems, and when we alter the environment, we also alter the entire network of that ecosystem. For instance, deforestation increases the incidents of malaria as it results in several favourable conditions for the Anopheles mosquito (the malaria carrying mosquito). One study has found that for every square kilometre of forest lost we can expect about six new cases of malaria. This could be due to deforestation exposing pools of water to sunlight. This results in increasing temperatures leading to a more ideal breeding ground for malaria. Mosquitoes are attracted to bodies of water. Deforestation creates ditches and puddles which are more likely to pool less acidic water which is more conductive to Anopheles larvae development. In additional to this, when tree stumps are left behind water can gather in pools in these stumps, attracting more mosquitoes.
  3. Deforestation for agriculture and livestock production. People have converted nearly half of the world’s land into agriculture. A study, by the School of Earth, Energy & Environmental Sciences at Stanford University suggests that when forests are cleared for agricultural use, the chances for transmission of zoonotic disease increases. The emergence of avian influenza has been linked to poultry farming; and the Nipah virus was linked to the intensification of pig farming and fruit production in Malaysia. This is due to the close and frequent interaction of humans and/or livestock with wildlife, increasing risk of spill over of disease.
  4. Deforestation exacerbates climate change which leads to increase risk of disease. Climate change is already having significant implications for human health, due to an increase in severe weather events and changing climatic conditions across the Earth. Drought, for example, leads to water scarcity and can result in poor sanitation. This increases the risk for a population to be exposed to potentially contaminated water. This can be seen currently in Northern Kenya where an epidemic of cholera spreads as severe drought takes over the region. At the same time, excess rainfall and flooding can also contribute to epidemics of waterborne diseases. One instance of this, occured in Milwaukee, USA where heavy rain resulted in contaminated runoff, which led to an epidemic of a disease named cryptosporidium. Changing climatic conditions also changes the reach of disease. This can be observed through the tropical mosquitoe anopheles, which carries malaria. As climates become warmer, the anopheles mosquitoes will increase its range, and therefore malaria will reach new regions. This is because anopheles thrive in warm, humid temperatures. As more regions reach suitable temperatures so will the opportunity for disease to thrive.

Deforestation is not only an ecological disaster but also a major threat to human health. Right now, we still have the opportunity to turn things around for the worlds rainforest in order to protect both environmental health as well as human health. The good news is, we all have the chance to have an impact on this. Just like the spread of COVID-19, what we do at home far away from the rest of the world, can have long-term impacts on the entire globe.

How can we turn this around?

Deforestation is driven by demand for products and this demand is driven by consumer choice. In order for us to end deforestation, we must realise the potential we have as consumers to influence demand and therefore influence deforestation. When you shop, you have an option to choose sustainable and/or deforestation free alternatives. By doing this, you will be reudcing the demand for deforestation, while also having a positive impact on human health. Everyone can seize this opportunity to lessen the risk of future outbreaks of disease. It’s as simple as supporting sustianable options when you shop.

Is the COVID-19 crisis enough for us to change and tackle the root of the global health crisis? Or will we go back to business as usual?

NOTE: Health and the environment are global issues, meaning it will take all of us working together, while being understanding of our differences. This means apprecciating that sustainable changes are only realistic for those who can afford it, have the access to it and the time and engery to make these changes. Those that are hit hardest by disease may also be the ones who do not have access to as many sustainable alternatives. It is crucial we be compassionate, and do our best for each other.

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