Michigan Sees Spike In Legionnaires Cases, Reports 107 Cases In First Half Of July

Michigan authorities are investigating a recent spike in reports of Legionnaires' disease. In the first half of July alone, the state saw 107 cases of the disease.

Between July 1 and 14, 107 cases of the disease were reported from 25 counties, the Michigan Department of Health and Human Services (MDHHS) said Monday. There is a 569% increase in cases this year compared to the same period in 2020 when there were only 16 cases. In 2019, 41 cases were reported in the first half of July.

"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," the MDHHS said.

No common source of the infections has been identified yet.

MDHHS chief executive Dr. Joneigh Khaldun added that the recent "rain, flooding and warmer weather" may also have contributed to the trend.

"We want everyone to be aware of Legionnaires' disease, especially if they may be at higher risk for illness and we ask that healthcare providers remain vigilant, and test and treat appropriately," Dr. Khaldun said in a news release.

Legionnaires' disease

People can contract Legionnaires' disease or Pontiac fever after getting exposed to Legionella bacteria, the Centers for Disease Control and Prevention (CDC) said. Legionnaires is quite similar to other types of pneumonia and can cause symptoms such as cough, muscle aches, shortness of breath, fever and headaches.

People can get infected when they breathe in small droplets that are contaminated with the bacteria. Although most "healthy people" don't fall sick after getting exposed, some are more at risk of getting sick. They include the elderly, those with cancer or underlying illnesses, people with weakened immune systems or who are taking immunosuppressant drugs, those with chronic lung disease and current or former smokers. About one in 10 people who get Legionnaires' disease die, the CDC said.

Legionnaires' risk in man-made water systems

While Legionella bacteria are found naturally in freshwater environments, they can become a "health concern" if they grow and spread in man-made water systems, the CDC said.

In 2020, for instance, health experts warned the public, particularly landlords, to be careful while reopening commercial buildings after the lockdown due to the coronavirus. The lack of flowing water in the pipes, coupled with temperature irregularities, are said to be favorable conditions for the bacteria to survive.

The MDHHS said the extended closures or limited use of buildings can create an environment for "potential amplification and transmission of Legionella bacteria."