Not yet investigated
What we have so far
It lives inside amoebae in plumbing. The 1976 outbreak that named it was traced to a hotel cooling tower, and it is still a plumbing disease.
This star is on the map because the show intends to take the question apart properly — the trials, how it is actually tested, whether the thing sold is the thing studied. That work is not done yet, and nothing here should be read as a conclusion. When the investigation is published it will appear on this page.