I am very curious as to whether the prevalence of NTM is some areas is also linked to the knowledge and expertise of doctors in recognizing and diagnosing it.

In other words, "if you look for it, you will find it." For example, although dry, dusty conditions and soil types in New Mexico would seem right for pockets of infection, little is diagnosed, but much of the state has limited access to medical care, so is it there and we don't know it? On the other hand, I know two people recently diagnosed who are totally asymptomatic - tests were done for something else and revealed NTM.

So until there is a simple, universally available test for NTM, do we really know it's prevalence?