(WSYM) — The Michigan Department of Health and Human Services is warning about an increase in reports of Legionnaires' disease.
MDHHS says that from July 1 to July 14, 107 cases of Legionnaires have been reported in 25 counties in Michigan. While that is a 56% percent increase over the same period in 2020, it also represents a 161% increase over 2019 when COVID-19 restrictions were not in place.
In southeastern Michigan, the confirmed cases include 19 in greater Wayne County, as well as another 17 in the City of Detroit, 17 in Oakland County, and 15 in Macomb County.
“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 in a news release. “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.”
Legionella bacteria causes two forms of legionellosis respiratory infections. 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.
While legionellosis cases are most common in the summer and early fall when warming, stagnant waters present the best environment for bacterial growth in water systems, this increase is higher than expected for Michigan for this time of year.
As many buildings are currently reopening after extended COVID-19 closures or periods of limited use, this may also create an environment for potential amplification and transmission of Legionella bacteria. Legionella bacteria are found naturally in freshwater lakes and streams but can also be found in man-made water systems. Potable water systems, cooling towers, whirlpool spas and decorative fountains offer common environments for bacterial growth and transmission if they are not cleaned and maintained properly. Warm water, stagnation and low disinfectant levels are conditions that support growth in these water systems.
Transmission to people occurs when mist or vapor containing the bacteria is inhaled. Legionnaires’ disease does not spread person to person. Risk factors for exposure to Legionella bacteria include:
- Recent travel with an overnight stay.
- Recent stay in a healthcare facility.
- Exposure to hot tubs.
- Exposure to settings where the plumbing has had recent repairs or maintenance work.
Most healthy individuals do not become infected after exposure to Legionella. Individuals at a higher risk of getting sick include the following:
- People over age 50.
- Current or former smokers.
- People with chronic lung disease.
- People with weakened immune systems from diseases, such as cancer, diabetes or liver or kidney failure.
- People who take immunosuppressant drugs.