Bacteria that the CDC found in October when investigating the most recent outbreak match five of seven genes with the 1982 bacteria.
“This indicates the Legionella found in the hospital in 1982 is almost identical to the Legionella found in this outbreak, suggesting that the pathogenic strain may have persisted in the hospital's water system for many years,” the CDC said.
Layers of slime and calcium in pipes could shelter the bacteria, said Janet Stout, a microbiologist who worked on the research team that responded to the 1982 outbreak.
“It's never completely killed because, as you can imagine, a water distribution system has many pipes, many sections” that disinfecting treatments might not reach, said Stout, who later worked in the VA Oakland pathogens lab before it was abruptly closed.
VA spokesman David Cowgill declined to comment, citing “pending investigations and legal claims.”
The VA Inspector General's Office and a subcommittee under the House Committee on Veterans' Affairs are separately reviewing the outbreak. U.S. Attorney David J. Hickton in Pittsburgh pledged to look into it when the inspector general's report is completed in March.
The family of veteran William E. Nicklas of Hampton said it plans to sue the VA. Nicklas, 87, died of Legionnaires' disease in November in the Oakland hospital.
The recent outbreak in the VA's Oakland and O'Hara facilities sickened as many as 21 patients from January 2011 through October 2012. Five of them died within 30 days of testing positive for Legionnaires' disease, an acute respiratory infection.
Another veteran infected with Legionella died in January in the Oakland hospital, but tests have yet to show where the patient contracted the bacteria.
The CDC did not test the water in the VA's H.J. Heinz campus in O'Hara. Asked whether Legionella found in the VA Butler facility's water in December were the same strain as that which caused the Oakland outbreak, the CDC referred questions to the Butler VA.
Amanda Kurtz, spokeswoman for the Butler VA, said she was “checking on the answer” on Friday afternoon but did not later respond.
The previous outbreak in VA Oakland occurred during a three-year period ending in 1982, when the hospital diagnosed about 100 cases of Legionnaires' disease — 30 percent of them fatal, Stout said.
Dr. Victor Yu led the 1982 research team for the VA Pittsburgh Healthcare System, which fired him in 2006. The VA should have known this strain lurked in its water system and done more to monitor it, Yu said.
“We know that it will come back if we don't monitor it,” Yu told the Trib. “They should've monitored, but they didn't, and that's the whole scandal — but you already know that.”
Epidemiologists say it's not surprising that the bacteria strain survived for so long in the hospital's water system. What sets this strain apart, however, is the key role it played 30 years ago in helping scientists learn how to detect and prevent outbreaks of Legionnaires' disease.
From the disease's discovery — as a result of a 1976 outbreak in the Bellevue-Stratford hotel in Philadelphia — until the 1982 study of the outbreak in the VA in Oakland, doctors believed mist from building cooling towers was the primary culprit in spreading Legionnaires' disease, Stout said.
In Pittsburgh, though, the disease occurred year-round, even when air conditioning was not in use. Yu, Stout and other Pittsburgh VA researchers tied the infections to the Oakland hospital's water system, Stout said.
“It was a game changer,” said Stout, who left the VA six years ago to co-found with Yu the Special Pathogens Laboratory, Uptown.
Because of the 1982 study by the Pittsburgh VA researchers, doctors look first to water systems when testing and preventing Legionnaires' disease, she said.
Dr. Lauri Hicks, a CDC epidemiologist, said the bacterium in the recent outbreak could be considered a “granddaughter or grandson” of the 1982 strain. The CDC has not seen this strain elsewhere, Hicks said.
“That was very important because it was very clear, given what we had from the patients and what we had from the environment, that this was a health care-associated outbreak. We have not investigated other outbreaks with that same strain,” Hicks said.
Dr. Ronald Voorhees, acting chief of the Allegheny County Health Department, said the recent outbreak in the Oakland VA points to the need for national standards to monitor and treat water-distribution systems in health care facilities.
“Unfortunately, there's not a national standard to say, ‘This is what you should do to minimize the problem,' ” Voorhees said. “People are trying different methods, and different methods are going to have different requirements.”
Legionella bacteria tend to survive in pipes, trapped in thin layers of micro-organisms called biofilms, he said.
“It's there, and it will re-establish itself, which is why treatments either have to be continuous or periodic to try to knock it back down,” Voorhees said. “But you never completely get rid of it.”
Because of that, hospitals that experience Legionella outbreaks should step up surveillance and testing, according to an August 2005 paper in the American Journal of Infection Control co-authored by the late Allegheny County Health Department Chief Bruce Dixon, who died on Wednesday.
In his last interview with the Trib on Feb. 13, Dixon advocated aggressive monitoring for Legionella, including testing hospital water systems, even if the disease was not identified in patients.
“They tried to minimize and obfuscate the problem,” Dixon said of the Pittsburgh VA system. “If I were associated with the VA, I'd be embarrassed as to what came out.”
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