Interesting theory about where the MAC came from - according to my doc, and the reading I have done, the bacterium is endemic in MANY places - in fact, just about everywhere. I too was diagnosed after several winters in South Texas and Arizona - and several bouts of what appeared to be desert fever or valley fever. But with long-term asthma & now the bronch and MAC diagnosis/treatment, I'm pretty sure location isn't going to make any difference unless I choose to live in a sterile bubble. So I take precautions like staying away from sick people & staying inside with filtered air when the yukky soil around me is being disturbed by raking, mowing, wind etc. I have also switched my South Texas gardening from in-ground to pots with sterilized soil, and wear gloves & mask when doing it. Pretty sure I look ridiculous, but my friends know how sick I was for the last few years, the rest I don't care about...