The outbreak, caused by bacteria in the hospital's water system, sickened at least 21 patients in 2011 and 2012, causing five deaths. The Pittsburgh Tribune-Review, using documents obtained under the Freedom of Information Act, reported the legionella bacteria had been discovered in the water system as long ago as 2007.
Several area congressmen told the newspaper they had asked for documents and never received them. The hospital is operated by the U.S. Department of Veterans Affairs.
"I want to work together with the VA. I don't want to be playing a cat-and-mouse game," Rep. Tim Murphy, R-Pa., said Monday.
The Tribune-Review reported it also found the U.S. Centers for Disease Control did not examine records on the water system when it investigated the outbreak.
Legionnaires' disease is a type of pneumonia caused by a bacterium first identified in 1976 when an outbreak occurred among American Legion members who had attended a conference at a Philadelphia hotel. The bacterium thrives in stagnant water and can be found in air-conditioning systems, hot tubs and similar places.
Murphy has co-sponsored a bill to require faster reporting on infectious diseases. The House Veterans Affairs Committee is scheduled to hold a hearing on the measure Wednesday.
"These revelations paint a troubling picture of rampant mismanagement and incompetence among some officials within the VA Pittsburgh Healthcare system," said Rep. Jeff Miller, R-Fla., the committee chairman. "Unfortunately, incompetence and mismanagement -- coupled with an extreme reluctance to come clean about the facts -- have defined the department's response to the tragic Legionnaires' disease outbreak in Pittsburgh."