Minnesota health officials reported three additional Legionnaires’ disease cases in the city of Hopkins, bringing the outbreak total to 12.

Legionella pneumophila bacteria/CDC
Legionella pneumophila bacteria/CDC

The Minnesota Department of Health (MDH) says two of the three new cases required hospitalization for their illnesses. The investigation into the source of the cases is ongoing.

Minnesota typically sees 50 to 60 cases of Legionellosis each year. More than 60 cases have been reported in the state so far this year, mirroring a national increase in cases in 2016.

Most people contract the disease by inhaling mist or vapor from a water source contaminated with the bacteria, Legionella pneumophila.   The disease is not contracted by drinking contaminated water, and person-to-person spread of legionellosis does not occur.

People of any age may get Legionnaires’ disease, but the disease most often affects persons older than 50.  The disease is rare in people younger than 20 years of age.  People at high-risk of acquiring the disease include current and former smokers, persons with chronic lung disease like emphysema or COPD, or those with compromised immunity (like patients who receive corticosteroids or have had an organ transplant).  People with underlying illnesses, such as cancer, kidney disease, diabetes, or AIDS are also at higher risk.

According to the Centers for Disease Control and Prevention (CDC), it is estimated that between 8,000 and 18,000 people are hospitalized with legionellosis in the United States each year.