Zoonoses, diseases that originated in animals and started to infect humans, are again in focus due to COVID-19 and the SARS-CoV-2 virus. But smallpox, measles, influenza and many others also came this way so we should by now know this happens and why:
[…] the likely source of SARS-CoV-2 is horseshoe bats. How, then, did the virus travel from a bat’s body to one of China’s most populous cities?
There are many possibilities: Bats may routinely infect people, wildlife, & livestock in rural areas of China; those people & animals may then travel to larger urban areas. Someone hunting bats or collecting guano may have started a chain of infection. Bats or other vectors may have been smuggled into China.
The fact that most of the early cases had some link to the Wuhan seafood market does not mean the outbreak began w/ bats sold there. It’s entirely possible the market was instead an amplifier: that someone(s) arrived at the market already infected and further spread the virus.
One could imagine thousands of possible trajectories & permutations, but if bats are the source of SARS-2, then some pathway involving the farming/hunting/trading of wildlife/livestock—& possible hybridization of a bat virus w/ another creature’s virus (pangolin?)—is probable.
Asia is not the only place where people hunt, breed, and eat wildlife. These are global practices.
Ferris Jabr continues with examples of the Nipah virus (reduced habitats -> more contact with humans), Lyme disease (reduced habitats -> more contact with humans) or the West Nile virus outbreak in California some years ago (the financial crisis -> swimming pools left abandoned -> breeding grounds for mosquitoes).
As we restructure Earth’s biosphere to suit our whims, we open hidden conduits between other animals’ microbiomes and our own…Other animals’ diseases have not so much leapt onto us as flowed into us through channels we supplied.
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