Health officials in a Virginia county are investigating an increase of Legionnaires’ disease cases.

The Virginia Department of Health on Thursday announced that the Chesterfield Health District (CHD) is investigating an increase in Legionnaires disease cases in the northeast part of the county.

The Virginia DOH said in a statement there have been 10 confirmed cases of Legionnaires’ disease since May 1 “among older adults and people with other medical conditions.”

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Legionnaires' disease is a “severe form of pneumonia,” according to the Mayo Clinic, which explains pneumonia is the inflammation of the lung that is typically caused by an infection.

“You can't catch Legionnaires' disease from person-to-person contact. Instead, most people get Legionnaires' disease from inhaling the bacteria,” the Mayo Clinic states, noting that older adults, those who smoke, or those with “weakened immune systems” are the most susceptible.

Legionella pneumophila, a bacterium, is usually the cause of the illness. It can be found in soil and water, but more commonly causes infection when it multiplies in water systems (e.g., hot tubs and air conditioners.)

The disease is treatable with antibiotics.

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“The CHD is working with the Centers for Disease Control and Prevention (CDC) to identify possible sources of exposure to Legionella. If any sources are identified, CHD will recommend strategies to stop the spread of Legionella. Investigations into increased cases of Legionnaires’ disease are complex. It is often not possible to determine the origin of the bacteria that infected people. The investigation is currently aimed at ruling out possible sources,” the statement added.

Alexander Samuel, the director of the Chesterfield Health District, told the Richmond Times-Dispatch that cooling towers may be the source of exposure — but was quick to note a definitive source may never be determined.

“The risk to residents or visitors to Chesterfield County is very small,” Samuel said in a statement. “Out of an abundance of caution, the health district recommends that individuals who become ill with pneumonia-like or respiratory symptoms, such as fever, chills, cough, shortness of breath, muscle aches and headache promptly seek medical care.”