Most of the infectious germs jumped from other animal host to human host. So-called zoonoses. Spillover is a single event during which a pathogen from 1 species moves into another species; such movement can result in an outbreak.
https://pmc.ncbi.nlm.nih.gov/articles/PMC5960580/
So: why not reduce the chance of next global pandemic and stop keeping exhausted animals in huge prisons?
Note to self: read Book - Spillover Animal Infection and the Next Human Pandemic