[FreeFull]

The thing about mad cow disease is that it's a prion disease, which operate very differently from viral and bacterial diseases. Prion diseases can just appear out of nowhere, and can be spread by consumption or contact with affected tissue/fluids. Viruses don't appear from nowhere but are rather subject to evolution. The way humans do make the spread of viral diseases worse is by cramming lots of animals together. So while humans aren't at fault for the existence of the virus itself, they can be at fault for its spread. It seems though that Newcastle disease is hard to control.

[proy24]

Yes a prion disease that is caused by forced cannibalism in animals. I understand, viruses evolve over time whereas prions are mutations of proteins...but my point is people are often directly or indirectly related to the cause and then they slaughter animals by thousands or even millions as in this case to cover their cause. PS: Not a very scientific argument but my general feeling. No need for the downvotes.

[autokad]

we prevent many diseases, we help many others, both directly and indirectly. its impossible to disambiguate things. Its almost as if assigning blame to something bad that happened is a pointless endeavour.