By NewsDesk  @infectiousdiseasenews

On Friday, the Chicago Department of Public Health (CDPH) reported an increase in cases of Legionnaires’ disease in the city this month.


In the first three weeks of July (1-21), 49 cases of Legionnaires’ disease were reported in Chicago, which is about a 3-fold increase in cases compared to the same period in 2020 (16 cases) and 2019 (13).

Among the 49 people with Legionnaires’ disease to date in 2021, 15 (31%) were admitted to the ICU and two individuals died.

A similar increase in illness has also been reported in Michigan. CDPH is investigating to find any common geographic or facility exposures. Legionnaires’ disease follows a seasonal pattern in Chicago, with an increased number of cases reported from June to October each year.

To date, no common sources of infection have been identified. CDPH continues to investigate cases and will provide updates if any common source is identified.

“This is a reminder to keep your water systems flushed and clean. Those with risk factors should seek care early if they develop symptoms, and clinicians should do appropriate testing and treat empirically,” said CDPH Commissioner Allison Arwady, M.D.

Legionnaires’ disease is caused by Legionella bacteria which live naturally in fresh-water. People can get Legionnaires’ disease when they breathe in water droplets containing the bacteria. It is not typically spread person-to-person. Symptoms of the illness include cough, shortness of breath, fever, muscle aches, and headaches. Most healthy people exposed to Legionella bacteria do not get sick, but people over 50-years-old, current or former smokers and people with chronic lung disease or weakened immune systems are at increased risk of Legionnaires’ disease.