No trees: What the landscapes where all recent pandemics originated have in common - 0 views
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pandemics ecosystems capitalism deforestation disease analysis
shared by Ed Webb on 31 Oct 20
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yellow fever, zika fever, dengue, chikungunya, ebola, SARS, Nipah virus, Kyasanur Forest disease, MERS, rabies, Rocky Mountain spotted fever, sleeping sickness, hantavirus-caused diseases, Japanese encephalitis, malaria
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All these diseases emerged – or re-emerged, more virulent and dangerous – as a result of human encroachment on forests. Historically, we might trace them to tropical rainforests, but right now we must look closer to home. Because the forest was, till very recently, right here somewhere, in and about your housing colony, around that gated high-rise and its adjacent slum.
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Diseases emerge when we clear forests, cut down trees, flatten hills, dam rivers, and squat on all this usurped territory. Within a 5 km radius of my home are breeding grounds for at least seven of those listed diseases. It’s not something we think about.
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Many emerging diseases, like those listed above, are zoönoses – diseases transferred from other vertebrates. Their origins can usually be traced to wildlife. They may have stayed on, unnoticed, in the wild and never made the species jump to infect us if a stable ecosystem had been left undisturbed
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The urban push into the forest forces bat populations to colonise human spaces and increases their vulnerability – and ours.
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Urbanisation provides new roosts, new sources of food and new company. Bats are sociable creatures. They form lasting relationships with home, and their urban circle of friends may embrace species that won’t roost together in the wild. And this commingling means a richer, more diversified stew of bat-borne viruses.
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When a bat flies, its metabolic rate rises to meet the exorbitant energy demand of flight, and its body temperature spikes to a high fever. In all mammals, fever upticks the immune process and slows viral replication. As the only mammal capable of sustained flight, the bat has evolved this pattern of spiking body temperature. The benefit is a more efficient immune system.
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Bats also spend a great deal of time in torpor – a state of suspended animation, when the body’s temperature drops. Was it this that encouraged viruses to co-evolve the ability to flourish across a wide range of temperatures?
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Coronaviruses are 30 per cent of the healthy bat’s virome. They cause diseases in other species – diarrhoeas and dysenteries; respiratory infections in cattle, dogs and swine; even peritonitis in cats. But before 2002, the worst illness they gave us humans was the common cold. Then, in 2002, SARS emerged. It had a death rate of 10 per cent. What had changed?
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Words like “coincidental” and “fortuitous” have no place in the narrative of an emerging disease. Instead, we must look for the motive force, the driver that brought about disease. Southeast Asia has lost 30 per cent of its forests in recent years. The deforested land is intensively cultivated. Urban growth is invasive. This abrupt proximity between humans and bats allows greater exposure to the viruses shed in bat saliva and guano, and provides an environment conducive to a rapidly diversifying spectrum of viruses. And since bat coronaviruses cause infections in domesticated species, intermediate hosts are aplenty.
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when there is a spillover, humans are immunologically naïve to the virus. This results in a virulent infection, and the virus quickly adapts to rapid spread between humans.
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At present, there are thousands of coronaviruses circulating in bats. Just seven of them have declared themselves in humans. As crowding increases, more may emerge. Can we predict what the next one will be like?
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The West has long jeered at Asia and Africa as “virus machines”. Such a label is deeply offensive to more than half the people on this planet, besides being scientifically untrue. Viruses are everywhere. Asia and Africa have been historically impoverished by European nations, either through genocide or colonisation. Disease was driven by conquest in the past, and racism in science is rooted in that memory. The language of science often echoes that inequality of power, and, thankfully, we’re growing more sensitive to it.
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Disease is driven by capitalism today: the forests of Asia, Africa, Central and South Americas are enslaved to richer nations to produce goods that serve few and bankrupt millions.