A CDC microbiologist pours water samples from a building experiencing a Legionnaires' disease outbreak into a filtration system to test for Legionella. Credit: Courtesy of the U.S. Centers for Disease Control

State health officials are investigating whether six cases of Legionnaires’ disease that have been reported in the greater Bangor area since late last year can be traced to a common source.

Area health care providers have diagnosed approximately one new case a month of Legionnaires’ disease in the area since November 2018, according to the Maine Center for Disease Control and Prevention.

All six people were hospitalized and one of them died, but the agency has not determined whether the bacteria caused the death, said Jackie Farwell, spokesperson for the Maine Department of Health and Human Services.

Maine CDC classified the recent group of cases as a cluster because they have occurred in a single geographic area but don’t have a common source of exposure that state health officials have identified. That’s not the same as an outbreak, which refers to a group of cases that can be traced to a common source.

Legionnaires’ disease is a type of pneumonia that can result when people breathe in droplets of water contaminated with a type of bacteria that naturally occur in freshwater environments such as lakes and streams, but that can spread to infrastructure such as air conditioning and large plumbing systems, according to Maine CDC.

Its symptoms include coughing, shortness of breath, fever, muscle aches and headaches, but most healthy people exposed to the bacteria don’t get sick.

The six diagnoses since last November mark an uptick for the region. Over the last five years, Penobscot County has averaged just three cases of Legionnaires’ disease annually, Farwell said.

The agency is also warning the public that Legionnaires’ disease can’t be spread from person to person and that residents of the greater Bangor area don’t need to do anything out of the ordinary because of the disease cluster.

“Maine CDC is announcing this investigation to make the public aware, but residents in the area do not need to take any specific actions in response,” Farwell said. “Maine CDC has alerted area health care providers so they can consider testing for the illness, which could lead to the identification of additional cases. All cases must be reported to Maine CDC.”

Farwell said that all the diagnosed people lived in the greater Bangor area, but didn’t specify what communities are included in that area. She also said the cases were not isolated to a single facility such as a nursing home.