The Chicago Department of Public Health is investigating after 49 cases of Legionnaires' disease were reported in Chicago since July 1, resulting in 15 people hospitalized and two dead.
This month's case count is about a three-fold increase compared to the last two years, with 16 cases reported in 2020 and 13 in 2019, according to CDPH.
“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 Dr. Allison Arwady.
Legionnaires' disease is caused by Legionella bacteria, which live in fresh water, health officials noted. People can get the disease when breathing in water droplets containing the bacteria.
Symptoms include cough, shortness of breath, fever, muscle aches and headaches, according to CDPH. Officials said that most healthy people exposed to the bacteria will not get sick.
People over the age of 50, however, as well as smokers, people with lung disease or weakened immune systems are at an increased risk for Legionnaires' disease, CDPH added.
Legionnaires' disease can develop in water systems during "prolonged building shutdowns or periods of limited use," as people saw with the COVID-19 pandemic, health officials said. Warm water, stagnation and low disinfectant levels can also support bacterial growth in waterways.
"People at high risk should see a doctor as soon as possible if they are experiencing unusual respiratory symptoms," CDPH said.