<<What fascinates me is the thesis that this may be a disease naturally
hosted in big game (e.g. leopards or elephants) and that, because numbers
of the natural host are dwindling, it's jumping species to something more
I'm unclear as to what mechanism might prompt a virus to jump from one species to another when hosts become scarce. That would
suggest a level of intent beyond the capacity of your typical virus, wouldn't it? Am I missing something?
However, as humans press further into the rain forests, we may come into closer contact with virus carriers we prevously encountered
only rarely. It wouldn't matter how large the population of, for example, leopards was, as long as we come into contact with them.
I think influenza is a good example of a virus, the precursors of which have plentiful host populations (pigs and geese, if I remember
correctly), but which still infects humans as a consequence of our close proximity to those hosts (predominantly in China).