May 9, 2017

University researchers continue investigation of Legionnaires’ disease in Genesee County

Note: Wayne State professor Shawn McElmurry and University of Michigan professor Nancy Love will be discussing these topics with Flint Mayor Karen Weaver today at 6:30 p.m. on WFLT 1420 AM Flint Radio. 

A research team led by Wayne State University is sharing findings from testing last fall and will resume sampling Flint water in June. In partnership with the City of Flint, Genesee County Health Department, Genesee County Medical Society as well as the Michigan Department of Health and Human Services, researchers are working to understand and reduce the incidence of Legionnaires’ and other infectious respiratory diseases in Genesee County, Michigan.

Legionella was detected in approximately 12 percent of 188 randomly selected homes in Flint and neighboring areas outside of Flint sampled from Sept. 6 through Oct. 29, 2016.  In most cases, concentrations of Legionella were low. In addition, the occurrence of Legionella in these homes was similar to what researchers have found in other communities.

Through systematic community-based sampling, the Flint Area Community Health and Environment Partnership (FACHEP) obtained 18 Legionella pneumophila isolates from environmental samples collected in 2016.  Sixteen of the 18 isolates were identified as L. pneumophila serogroup 6.

“This is important because the urine antigen test commonly used to detect Legionnaires’ disease in patients targets a different type of L. pneumophila (serogroup 1). Therefore, it is important for medical professionals to continue to analyze sputum samples to diagnose Legionnaire’s disease,” said Dr. Michele Swanson, a microbiologist from the University of Michigan. 

Enhanced monitoring for the disease in 2016 resulted in more than 300 tests – urinary antigen and sputum – being negative for L. pneumophila.

"During 2016, 17 confirmed cases of Legionnaires’ disease were reported in Genesee County, and no deaths were reported; the majority of the cases occurred in residents (13 of 17) living outside of Flint during the two weeks prior to their illness" said Dr. Eden Wells, Chief Medical Executive, from Michigan Department of Health and Human Services.

Through an agreement with the MDHSS that strictly protects patient confidentiality and privacy, FACHEP also obtained 33 Legionella pneumophila bacterial isolates from patients with Legionnaires’ disease. The isolates were from patients treated in Genesee, Oakland, and Wayne counties between 2013 and 2016 but they were not limited to the residents of those counties. Of the 33 patient isolates, there were 16 different strain types of L. pneumophila based on analysis of Legionella DNA.

One of the environmental L. pneumophila serogroup 1 isolates obtained in a residence in the city of Flint was found to be the same sequence type (ST1) as the strains from four patients treated for L. pneumophila infections. Sequence type 1 strains have been isolated from patients in other outbreaks and, according to the work of others, were also isolated from water at McLaren Hospital in Flint. Additional laboratory and epidemiological analysis is required to determine the likelihood that any persons acquired Legionnaires’ disease from water or mist in their home plumbing systems that contained L. pneumophila.

Shawn McElmurry, leader of the FACHEP research group, noted that the investigation is challenging.

“These are very complicated questions, and we are working with a team of investigators including epidemiologists, microbiologists, water engineers and statisticians to understand what happened in Genesee County,” McElmurry said. “Most important is the assistance of residents who continue to work with us on this challenging problem. We look forward to collecting and analyzing additional samples to help us better address questions.”

Legionella bacteria grow best in warm water when adequate disinfection is not maintained. Common locations for the bacteria are cooling towers and plumbing systems of large buildings, hot tubs, hot water tanks, decorative fountains and pools. Legionnaires’ disease is more common in warmer months.

An outbreak of Legionnaires’ disease occurred in Genesee County following the change from water supplied by the Detroit Water and Sewerage Department to water from the Flint River, supplied by the City of Flint. Legionnaires’ disease may occur when individuals inhale water or mist containing Legionella bacteria.

“It is important that all necessary steps be taken to determine why this outbreak occurred so that the health of the residents of Genesee County can be protected,” said Dr. Marcus Zervos, of Henry Ford Health System and a member of the Wayne State team.

The FACHEP research group, a consortium led by WSU that includes the University of Michigan, Michigan State University, Kettering University, Colorado State University, and Henry Ford Health System, is investigating the relationship between changes in the source of drinking water and the Legionnaires’ outbreak.

Legionnaires’ disease is an illness that affects lungs and breathing. The disease starts with flu-like symptoms such as fever, headache, muscle aches, and chills. In some people, typically the elderly, smokers, or those with weakened immune defenses, more serious symptoms can develop in as little as one to two days. People with severe Legionnaires’ disease may develop high fever, a cough that is usually dry but sometimes produces mucus, difficulty breathing, chest pains, chills, and diarrhea. People who experience these symptoms should seek immediate medical attention and may require admission to the hospital. 

Individuals can minimize their susceptibility to developing Legionnaires’ disease by maximizing their lung health. Quitting smoking and receiving the pneumococcal and flu vaccines are three steps people can take to maximize their lung health.

For some residents who are at higher risk for Legionella and also for lead toxicity, the Genesee County Medical Society recommends that they use only reverse osmosis-purified bottled water or other sources of water purified by reverse osmosis (e.g. home units). 

“When we do not have clear data, we err on the side of safety. Residents at higher risk for Legionnaires’ disease and other infections as outlined in our press release of March 29, 2017 should continue to use bottled water,” said Dr. Laura Carravallah of the Genesee County Medical Society. “If you have questions about whether you fall into a high-risk group for Legionnaires’ disease, please ask your health-care provider.”

The Flint Area Community Health and Environment Partnership research team is funded in part by a contract from the MDHHS.

Additional information about Legionnaires’ disease can be found at the Genesee County Health Department, the Michigan Department of Health and Human Services and the Centers for Disease Control and Prevention website.


Kara Gavin
Phone: 734-764-2220
Matt Lockwood
Phone: 248-622-8060

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