The outbreak occurred at the Pittsburgh Veterans Affairs Hospital in Oakland. In addition to the House committee, the VA's inspector general also is investigating.
The VA has only said that one person has died from contracting Legionella bacteria at the hospital. But the Post-Gazette had learned from two other families that they suspect their loved ones died from contracting the disease at the hospital.
The CDC report appears to confirm not only those two families' suspicions but that there were two more victims, for a total of five.
The subcommittee hearing will include testimony from someone at the Pittsburgh VA who is "most knowledgeable and able to answer questions," said U.S. Rep. Mike Doyle, D-Forest Hills, who is not on the subcommittee but requested the hearing along with U.S. Rep. Tim Murphy, R-Upper St. Clair.
Mr. Doyle said subcommittee staff told him the hearing may also include testimony from water treatment experts called in to help the Pittsburgh VA with the outbreak over the last year, as well as Victor Yu and Janet Stout, former Pittsburgh VA researchers.
Dr. Yu and Dr. Stout, both renowned Legionnaires' experts who left in 2006 and 2007, respectively, in a dispute with the Pittsburgh VA's management, believe the outbreak was the result of the VA's poor management and maintenance in recent years of the water treatment system they installed at the hospital in 1993.
The Pittsburgh VA announced Nov. 16 that four patients had contracted Legionnaires' during stays at the hospital in Oakland, which had been trying to get the spread of the Legionella bacteria under control in its water system for nearly a year at that point.
Six days later, it announced a fifth patient had contracted the pneumonia-like disease in the hospital. A day later, that patient, William Nicklas, 87, of Hampton died.
Two other families later told the Post-Gazette that men in their families -- John McChesney, 63, of Columbus, Pa., who died Oct. 23, and John Ciarolla, 83, of North Versailles, who died July 18, 2011 --also died after contracting Legionnaires' following stays at the University Drive facility.
The CDC report does not list the dates of death of the five people who died over the last two years, listing only age and the date of onset of the disease and the date of diagnosis of the disease.
But the timing and the ages clearly refer to not only Mr. Nicklas, but also Mr. McChesney and Mr. Ciarolla, though it says only in Mr. Nicklas' case was the source of Legionnaires "definitely" at the Pittsburgh VA. It says Mr. McChesney and Mr. Ciarolla "probably" contracted the disease at the hospital.
The identities of two other people who died after contracting Legionnaires are not known, though the report says they were a 74-year-old who contracted and was diagnosed with Legionnaires at the hospital in October 2011 and a 65 year-old who contracted and was diagnosed with the disease at the hospital in June 2012.
Both of those victims are believed to have "probably" contracted the disease at the hospital, according to the CDC report.