Novel swine flu discovered in China -- and it has potential to create a second pandemic: report

[magicarpet]

15. Proliferation of wet markets,...

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But researchers of zoonotic diseases — diseases that jump from animals to humans – pinpoint the wet markets in mainland China as particularly problematic for several reasons. First, these markets often have many different kinds of animals – some wild, some domesticated but not necessarily native to that part of Asia. The stress of captivity in these chaotic markets weakens the animals' immune systems and creates an environment where viruses from different species can mingle, swap bits of their genetic code and spread from one species to another, according to biologist Kevin Olival, vice president for research at the EcoHealth Alliance. When that happens, occasionally a new strain of an animal virus gets a foothold in humans and an outbreak like this current coronavirus erupts.

(end snip,.... much more at link)

https://www.npr.org/sections/goatsandsoda/2020/01/31/800975655/why-theyre-called-wet-markets-and-what-health-risks-they-might-pose