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Most of the more than 90 Legionnaires’ disease cases during the deadly 2014-15 outbreak in the Flint area were caused by changes in the city’s water supply — and the epidemic may have been more widespread than previously believed, according to two studies published Monday.

The risk of acquiring Legionnaires' disease increased more than six-fold across the Flint water distribution system after the city switched from the Detroit area water system’s Lake Huron source to the Flint River in April 2014, according to a report in the Proceedings of the National Academy of Sciences.

Researchers concluded the increase in Legionnaires’ cases — which killed at least 12 people and sickened another 79 individuals over two years — “was consistent with a system-wide proliferation of Legionella bacteria.” The report estimates that 80 percent of Legionnaires’ cases during the outbreak can be attributed to the change in water supply.

Both studies were conducted by the Flint Area Community Health and Environmental Partnership, a research team that includes scientists from Wayne State University, the University of Michigan, Colorado State University and other institutions.

The Michigan Department of Health and Human Services disputed results of the studies. “By publishing these inaccurate, incomplete studies at this point, FACHEP has done nothing to help the citizens of Flint and has only added to the public confusion on this issue,” said Health and Human Services spokeswoman Geralyn Lasher, who forwarded the statement.

The department hired an outside firm, KWR Watercycle Research Institute, to provide an “external, independent third party” review of the research and gave a detailed rebuttal of the Academy of Sciences article.

“Both MDHHS and KWR found numerous flaws in the articles which were brought to (the research team’s) attention and appear to remain unaddressed,” Lasher said.

The department also noted it has discontinued state funding for the research partnership because the group rejected KWR’s oversight. State officials in 2016 promised to provide $4.1 million to the group.

The state provided $3.1 million in 2016, but discontinued funding in December after the partnership refused to have its work overseen by KWR, said Shawn McElmurry, an environmental engineering associate professor at Wayne State University who leads the research partnership.

The study found “there was clearly a large proportion of cases that can be attributed to the switch in the water,” McElmurry said.

“While there may not have been a good enough epidemiological investigation at the time, and the data may not have been collected..., this makes it very clear that the increase in the Legionnaires’ cases is attributable to the change in water quality.”

Legal impact of studies

The Academy of Sciences study will hurt the defense cases for six current and former state and local officials facing involuntary manslaughter charges related to the outbreak, including state Health and Human Services Director Nick Lyon and state Chief Medical Executive Dr. Eden Wells, a legal expert said.

The study “could be helpful to the prosecution,” said Peter Henning, a professor of law at the Wayne State University School of Law and a former federal prosecutor.

“The standard for this kind of a conviction is whether a rational juror could find there is sufficient evidence of guilt,” Henning said. “Under this standard you don’t have to have absolute certainty” that the failure to issue a public health warning about the Legionnaires’ outbreak helped lead to the deaths.

Michigan State University law professor Adam Candeub told The News in September: “You are going to have to show that these increased, dangerous impurities in the water present a clear and immediate danger, and you have to show that these impurities in the water actually caused the Legionnaires’ disease.”

Wayne State’s McElmurry has testified for Flint Special Prosecutor Todd Flood in the preliminary exams for Lyon and Wells, saying state health officials stalled his team and gave it insufficient funding to sample for bacteria in Flint area water in 2016. Gov. Rick Snyder requested the partnership do the Legionnaires’ research.

The report tested the state’s claim that the outbreak originated at McLaren Flint Hospital — a contention the hospital vigorously rejected. The Michigan Department of Health and Human Services last February issued an order demanding McLaren "immediately correct conditions" to reduce Legionella bacteria.

State officials noted that a genetic link was found between Legionella bacteria isolated from the sputum of three Flint residents, two of whom had been treated at the hospital, and Legionella found in water at the hospital. McLaren contended the Legionella entered the hospital from the city’s water supply.

To test the state’s hypothesis, McElmurry’s group repeated their analysis after excluding all Legionnaires’ disease cases that could plausibly be related to Flint McLaren Hospital. The results showed that the hospital could not possibly have accounted for the increase in Legionnaires’ disease during the water crisis, according to the study.

 Water switch spike

An analysis of data on Legionnaires’ cases in Genesee, Wayne and Oakland counties from 2011 to 2016 found that cases of Legionnaires disease spiked after the water switch, according to the study. The risk decreased after public announcements urging residents to boil their water, when people began avoiding use of the water.

On Jan. 13, 2016, Snyder publicized the Legionnaires’ outbreak for the first time to the public at a hastily arranged Detroit press conference.

A Detroit News review of state and Genesee County emails found that six U.S. Environmental Protection Agency officials were told in late March 2015 the state would alert the public about the rise in Legionnaires’ cases. But two months later, there was no announcement, and a Michigan health official’s email to the Centers for Disease Control and Prevention declared “the outbreak is over.”

The likelihood of getting Legionnaires’ disease also increased in communities adjacent to Flint, where many residents commute to Flint for jobs, according to the NAS report. Prosecutors have charged the six current and former government officials with helping to cause the death of Robert Skidmore, an 85-year-old Genesee Township man.

Researchers concluded the levels of chlorine added to the city’s water supply were not enough to combat the proliferation of Legionella that followed the city's water switch.

As Flint increased levels of chlorine added to the water during the outbreak, the number of cases declined, according to the NAS study. After the city switched back to the Detroit area water system known as the Great Lakes Water Authority in October 2015, the number of Legionnaires’ cases dropped to historically low levels. Lead levels in the water have also fallen below the federal standard of 15 parts per billion that triggers mitigation.

As Flint increased levels of chlorine added to the water during the outbreak, the number of cases declined, according to the NAS study. The city switched back to the Detroit area water system known as the Great Lakes Water Authority in October 2015, and lead levels in the water have fallen below the federal standard of 15 parts per billion that triggers mitigation.

Flint residents still are being urged to drink bottled water or only water from taps equipped with approved filters.

Study: Undetected cases

Another study published by the partnership Monday in the journal mBio found that the Legionella bacteria collected from Flint residents’ homes is from a strain that is not readily detected by urine-antigen tests, the most commonly used diagnostic test for Legionnaires’ disease. This means many cases of this severe form of pneumonia may have gone undetected.

The state disputed both the methodology and conclusions of the mBio study in a detailed memo released to the media Monday.

Most U.S. cases of Legionnaires’ disease are caused by Legionella pneumophila bacteria classified as Serogroup 1, which can be detected by urine-antigen testing. But the majority of strains found in Flint were Serogroup 6, which can’t be detected in the urine.

Diagnosis of Serogroup 6 requires a throat culture. But American health care workers rarely swab throats to test for Legionella since most cases are Serotype 1 and are detected by the cheaper, faster urine-antigen test.

“If hypothetically somebody had become infected with Serogroup 6 and they went to the hospital with pneumonia symptoms, they might get the urine antigen test and be told, ‘No, you don’t have Legionnaires’ disease,’” said Dr. Michelle Swanson, a professor of microbiology and immunology at the University of Michigan and a co-author on both studies published Monday.

“They would then just be given a broad spectrum antibiotic and be treated, and just be said to have community-acquired pneumonia, without stating what microbe is causing this.”

Staff Writer Leonard N. Fleming contributed

kbouffard@detroitnews.com

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