Seven New Jerseyans in Passaic and Bergen counties have been diagnosed with Legionnaires’ disease since early November, according to the New Jersey Department of Health.

The state and county health departments are investigating the cases to see where they came from and if they’re related. All seven individuals were hospitalized, health department spokesperson Dalya Ewais said.

New Jersey Health Commissioner Judith Persichilli said in a statement that the risk to residents of, and visitors to, the counties was low.

But the health department still recommended “out of abundance of caution” that people who live or work in the area and who have respiratory symptoms visit their health care providers for evaluation immediately. Those could include fever, chills, cough, shortness of breath, chest pain, muscle aches and headache, the health department said.

Ewais stressed people could also be exposed when spending time in the area for other reasons — like shopping, work and other social activity.

Legionnaires' disease is an infection caused by breathing in tiny water droplets containing Legionella bacteria. The microbes can lurk in water from plumbing, building climate control systems and even fountains. Older adults, immunocompromised people and those with chronic health conditions are more vulnerable to infection. Otherwise, the disease is uncommon.

Symptoms can take weeks to develop, and resemble those of other respiratory illnesses, according to the Centers for Disease Control and Prevention. About 10% of Legionnaires’ patients die from complications of the illness, according to the CDC, but most recover after receiving antibiotics. Legionella bacteria can also trigger a less severe disease called Pontiac fever, with a shorter onset and milder symptoms.

The diagnosed individuals were six men and on woman, ages 52-77, Ewais said.

Local health officials reported the cases to the state health department between Nov. 9 and Dec. 21 of this year. One additional case is still being investigated, the health department statement said. It didn’t specify which municipalities had cases, but Ewais said the cases were in the areas "roughly to the west and south of the High Mountain Park Preserve."

Fair Lawn Health Officer Carol Wagner confirmed one of the cases was in her borough, but said she couldn’t provide more details without violating patient privacy protections. A Passaic County spokesperson told NorthJersey.com there were cases in the city of Passaic, the city of Paterson and the township of Wayne.

Wagner stressed “no commonality was found between any of the cases, and there’s no common source.”

“They just want to get the word out to the medical providers that if anybody comes in with a breathing issue, to consider that it possibly could be Legionnaires' disease,” she said.

It’s hardly the state’s first Legionnaires’ scare. The health department says it gets hundreds of reports of the disease each year. Earlier this month, Camden County’s health department reported a handful of cases among Pennsauken residents. And in October, health officials announced they had found the bacteria in water samples from more than a dozen homes across Ewing, Trenton, Lawrence and Hopewell Township, all within the service area of Trenton Water Works.

This story has been updated with additional details about Legionnaire's cases provided by the New Jersey Department of Health.