Unlike tuberculosis (TB), which is spread from person to person, nontuberculous mycobacteria (NTM) infections are not considered contagious. There is no evidence that the infection can be transmitted from one person to another. How and why people become infected with NTM is not clear and the nontuberculous mycobacteria (NTM) causes are still under investigation.
Although the germs are found easily in water and soil, they do not affect most people. Doctors believe that some people who become infected have an unknown defect in their lung structure or function or in their immune systems. People who have damaged lung tissue from diseases such as emphysema, bronchiectasis, adult cystic fibrosis or previous TB infection appear to be at greater risk for developing a NTM infection. People who are immunocompromised such as those who receive strong immunosuppressant medications such as prednisone or remicaid have a greater risk of developing an NTM infection that affects all organs of the body, not only the lungs. Patients with AIDS may also develop NTM infections.
Currently there is a "hypothesis" or "theory" about acquiring NTM from a shower. In considering an apparent increase in the number of NTM lung disease cases seen over the past 25 years, it has been noted by researchers in the field, such as Dr. Pace in Boulder and Dr. Falkinham in Virginia, that NTMs may be commonly recovered from home water systems.
We speculate that in the recent past people tend to take showers rather than bathe in a tub, and when showering in a closed stall the concentration of NTMs could be higher. Additionally, to save energy, water heaters have lower temperatures now, which could allow more NTM growth in the water. These are preliminary findings and further research is required to confirm these theories.