How is the legionnaire disease contracted and is it found more commonly in people in the war zone?

Legionnaires' disease is the most severe of two forms an
infection of legionellosis that manifests as pneumonia.  The less severe pontiac fever
is caused by the same infection; however, it produces a condition much more resemblant
of influenza.

The infection usually occurs after inhaling
an aerosol that has the bacteria, which originates from any infected water source.  When
the infected water is disturbed the bacteria is evaporated into the air that are then
inhaled.  Areas with poor ventilation like prisons are the most vulnerable to spreading
the infection because it spreads through the entire room.  The disease is mostly
associated with hotels, cruise shops, hospitals with old ventilation systems because of
the number of people in a smaller space in all of them.

It
is not isolated just to war zones, the name is an historical one dating to the first
outbreak in Philadelphia in 1976 in the Bellevue Stratford Hotel where members of the
American Legion had gathered for the American Bicentennial.  Outbreaks since then have
been in the UK in 1985, the Netherlands in 1999, Australia in 2000, Spain in 2001, the
UK again in 2002, and Norway in 2005.