And if you read the fox news article it specifically says the Lung event was NOT (excuse me for 'shouting' I can't get italics to work on this) at the governors mansion and there is no msytery about what the infection is; just how people got it.

Health officials worked to narrow the potential locations and connecting factors to the outbreak and determined many of those affected had attended an American Lung Association event at Terrace Hill on November 29th.

Hundreds of pages of e-mails, correspondence and other documents obtained by The Associated Press under Iowa's freedom of information law, as well as interviews with health officials, show a methodical inquiry into the outbreak. The investigation led to the 139-year-old governor's mansion just west of downtown Des Moines.