In April of 2023, health officials in Grand Rapids, Minnesota, began investigating an outbreak of Legionnaires' disease. A total of 34 cases of the disease were associated with this outbreak. Thirty people required hospitalization, and two people died as a result of their illness. The investigation by the Minnesota Department of Health (MDH) determined that the municipal water system was the only common exposure reported by those who got sick.
To address the issue, a chlorine disinfection system was installed at the public water supply and went into use in June 0f 2024. No cases of Legionnaires' disease have been reported since that time.
Legionella is a bacteria found in freshwater sources all over the world. However, it is the conditions in built water systems that most often allow Legionella to thrive in large enough amounts to cause Legionnaires' disease. These conditions include water temperatures between 77° and 108° F, stagnant water, the presence of sediment and biofilm in pipes and fixtures, and the absence of disinfectant.
Legionnaires' disease is a serious type of pneumonia caused by the Legionella bacteria. It spreads when people inhale tiny water droplets (such as those produced by showers, misting stations, and hot tubs) that contain the bacteria. It does not spread from person to person.
Common symptoms of Legionnaires' disease include:
While anyone can get Legionnaires' disease, people who are over 50 and are current or former smokers are at increased risk. Other factors, such as lung disease, kidney disease, liver disease, cancer, and conditions or medications that affect the immune system, can also increase a person's risk.
If you develop pneumonia symptoms, see a doctor right away. Be sure to mention if you may have been exposed to Legionella, have used a hot tub, spent any nights away from home, or stayed in a hospital in the last two weeks.
Legionnaires' disease is typically treated with antibiotics, and cases often require a hospital stay. Approximately 1 in 10 cases result in death.
Proper maintenance of building water systems and devices is the best line of defense against Legionnaires' disease. Monitoring water temperatures, maintaining proper disinfectant levels, and preventing stagnant water conditions are key.
Building owners and managers can consult the toolkit "Developing a Legionella Water Management Program" which was developed by the Centers for Disease Control and Prevention (CDC). This toolkit provides information on the American Society of Heating, Refrigerating and Air-Conditioning Engineers standards for water management programs.
The University of Alabama at Birmingham's Alabama Regional Center for Infection Prevention & Control, Training and Technical Assistance recently hosted the webinar "Legionella Prevention and Water System Management in the Nursing Home."