Harold Kestenholz
Tommy Tyler, a web search for the word Legionella brings untold numbers of such references, for instance: http://www.dhmh.state.md.us/publ-rel/html/0800legion.htm
Like most pathogens, they need to be in sufficient numbers to overcome immune systems.
Most gas hot water heater manufacturers do not provide controls on new products that are able to be set below 120F.
