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Synopsis: With worsening trajectory of climate change parameters across the world, an increased incidence of zoonotic diseases is also being witnessed.
What are the key drivers of increased incidence of zoonotic viruses?
Viruses account for almost 50% of new and emerging diseases. Since mid-20th century about 75% of all emerging viruses are zoonotic, they spill over into humans from wild animals.
The key drivers of this process are deforestation and climate change.
| The 20th century had three pandemics (Influenza 1918, 1957 and 1968) but the 21st century has already experienced two (Swine Flu 2009 and Covid-19) with a few narrow misses like SARS, Ebola and Zika. |
Why zoonotic disease incidence is increasing?
Though humans comprise only 0.01% of the Earth’s biomass, we have changed this planet so much that we are in Anthropocene, or the Age of Man since the mid-20th century.
Increasing livestock population, with genetic links to wild animals and proximity to humans, acts as a natural intermediary for the spillovers. South and Southeast Asia with high densities of human and livestock populations are particularly at risk.
Deforestation brings wild animals near both livestock and humans, increasing the risk. For example, Malaysia cleared about 5 million hectares of primary forests between 1983 and 2003 for industrial logging, palm oil plantations etc.
Redistribution of species: Climate change is leading to increased global expansion and redistribution of the Aedes mosquito, which is the vector for several known human diseases such as yellow fever, dengue, chikungunya, rift valley fever, Zika and lymphatic filariasis.
Source: This post is based on the article “COP26, Covid & our species” published in Business Standard on 1st Nov 2021.
