Animals are absolutely a primary vector for infectious disease. No, there's no definitive evidence as of yet of patient 0, though the cluster of early cases in China had strong connections to the wet market in Wuhan. It's not necessarily the eating of the animals directly, but indirectly – because wild animals are kept stressed, in cages, next to other domesticated animals and people.

Even with conventional animal agriculture, things like bird flu and swine flu are a serious threat.