Bacteriophages in the bloodstream is different from our gut. Our gut has a lot of bacteria too but the immune system rarely bothers with them till they start po

Bacteriophages in the bloodstream is different from our gut. Our gut has a lot of bacteria too but the immune system rarely bothers with them till they start popping up outside the guy. We've coevolved with phages for a long time. So our immune system knows that they are mostly benign but don't like them hanging around the bloodstream and flush them out pretty quick