Patrons who stayed at Aria between June 21 and July 4 will be notified that they may have been exposed to Legionnaires' disease, which is a form of pneumonia. While Aria officials are focusing on those specific dates, six former patrons of the Aria who stayed at the hotel from December 2009 to April 2011 have come down with the disease. The disease can be serious and can cause death in 5-30% of cases. Click the link below for more on this.