Legionnaires’ Disease On The Rise In Michigan: What To Know

LANSING, MI — A recent increase in reports of Legionnaires' disease across Michigan is being investigated by the Michigan Department of Health and Human Services, state officials said Monday.

More than 100 cases of Legionnaires’ disease have been reported across 25 Michigan counties between July 1-14, health officials said.

“Recent weather trends including rain, flooding and warmer weather may be playing a role in the rise of reported legionellosis cases this summer,” said Dr. Joneigh Khaldun, MDHHS chief medical executive and chief deputy director for health. “We want everyone to be aware of Legionnaire’s disease, especially if they may be at higher risk for illness and we ask that healthcare providers remain vigilant, and test and treat appropriately.”

State authorities said environmental factors — such as the heat or rainfall — often are tied to increased reporting. But the state has seen a 569 percent increase in reports from the same timeframe in 2020 when 16 cases were reported. Forty-one cases were reported during that stretch in 2019, the state said.

Health authorities said Wayne County has reported 19 of the cases, while 17 cases have been reported in Oakland County and in Detroit. Fifteen have been reported in Macomb County.

What is Legionnaires Disease?

Legionella bacteria causes two forms of legionellosis respiratory infections, state health officials said. Legionnaires’ disease is an infection with symptoms that include fever, cough and pneumonia. A milder form of legionellosis, Pontiac fever, is an influenza-like illness without pneumonia that resolves on its own.

With many buildings reopening after extended closures due to the coronavirus pandemic, some of these environments may present the potential for amplified transmission, officials said. Stagnant water presents the best environment for bacterial growth in water systems, the state said.

How Does Someone Contract the Disease?

MDHHS officials said transmission to people occurs when mist or vapor containing the bacteria is inhaled. Legionnaires’ disease does not spread from person to person. Risk factors for exposure to Legionella bacteria may include recent travel, recent stays in a healthcare facility, exposure to hot tubs or exposure to settings where the plumbing has had recent repairs of maintenance work.

Most healthy people do not become infected after exposure to Legionella, officials said. People at a higher risk of getting sick may be over age 50, current or former smokers, have chronic lung disease, have weakened immune systems, or take immunosuppressant drugs.