Not so. There are plenty of things in your home environment to keep your immune system busy. Most of its activity appears like nothing is attacking you because

Not so. There are plenty of things in your home environment to keep your immune system busy. Most of its activity appears like nothing is attacking you because it’s just so good at what it does most of the time. Without humans to infect, there really isn’t a way for new pathogens to readily emerge naturally that are able to infect humans. Anytime you let a pathogen use your body to reproduce then pass it to someone else you are taking part in its evolution and adaptation to the human immune system which does not really change much unless there is a big human extinction like the Black Plague. Western Native tribes were highly susceptible to European pathogens not because they were isolated but because the pathogens had a lot of time to evolve various nasty traits by freely spreading throughout the European and other populations prior to being introduced to the natives. Viruses don’t just become highly lethal to humans without spending considerable amount of time being spread around by humans or an organism very closely related to humans.