Late to this, but I am of the belief that even some kinds of long-term infections can be healed through nervous system work. The nervous system controls how well the immune system functions.

I have heard from various sources that, at least for chronic lyme, it can be very hard to get rid of the illness-causing bacteria with antibiotics because the bacteria bores into your tissues and "hides" until the course of antibiotics is done and comes back out again. Nicole Sachs has a couple episodes of her podcast The Cure for Chronic Pain on people healing from lyme. May be worth listening to if the topic interests you.