Humans have always been attacked by novel pathogens. This process has been going on for millennia. But it does seem to be happening very fast in these modern times.
We most likely will get it from an animal and it will probably be the result of changes in human ecology --humans moving into new areas of the world and coming in contact with unknown pathogens.
A total of 38 apparently new pathogen species associated with infectious diseases of humans have been reported in the past 25 years.
Although we are developing a better understanding of the biology, epidemiology and evolution of species jumps, we are not yet able to predict future infectious disease threats.