The City of Hopkins reported today that state health officials have  confirmed three additional cases of Legionnaires’ disease, bringing the total to 20. The latest (most recent) illness onset date is consistent with exposure before remediation began on Sept. 9 and 10.

This image shows Legionella colonies growing on a Petri dish. Image/Otto Schwake
This image shows Legionella colonies growing on a Petri dish.
Image/Otto Schwake

The new cases fall into the age range for all cases of late 20s to late 90s (median age 59). Most of the cases (14) are male, which is consistent with other Legionnaire’s outbreaks. Sixteen (16) of the 20 cases were or are hospitalized. One fatality has been reported.

The Minnesota Department of Health  is continuing to investigate potential sources of the outbreak. None has been confirmed nor ruled out at this point.

This is the largest Legionnaires’ disease outbreak in Minnesota in two decades. 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.

Legionellosis is a bacterial disease of the lungs caused by Legionella pneumophila. The disease can range from a mild respiratory illness to severe pneumonia and death. The most common form of legionellosis is known as “Legionnaires’ disease,” named after an outbreak in 1976 when many people who attended an American Legion conference in Philadelphia became ill.

Most people contract the disease by inhaling mist or vapor from a water source contaminated with the bacteria.   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.