PO Box 360
Trenton, NJ 08625-0360

For Release:
November 8, 2023

Kaitlan Baston, MD, MSc, DFASAM
Acting Commissioner

For Further Information Contact:
Office of Communications
(609) 984-7160

NJ Health Department Investigating Legionnaires’ Disease Cases in Middlesex, Union Counties

Case Counts Higher Than Typical Reports During Time Period

 TRENTON – The New Jersey Department of Health (NJDOH) is investigating an increase in Legionnaires’ disease cases in residents across Middlesex and Union counties and encouraging residents who develop symptoms suggestive of Legionnaires’ disease to seek medical evaluation.

As of November 6, NJDOH has been notified of 21 individuals from Middlesex County and 20 individuals from Union County who were sick and tested positive for Legionella, the bacteria that causes Legionnaires’ disease. The onset of symptoms occurred between August 3 and October 24, 2023. To date, no deaths have been reported. On average, each of these counties receives six to eight confirmed reports of Legionnaires’ disease from August to October each year.

NJDOH is actively collaborating with local health departments in Middlesex and Union counties to investigate these cases and any potential sources of infection. In mid-October, NJDOH alerted local health departments, health care providers, and other public health partners in the area regarding the elevated number of reported cases. To date, a common exposure among cases has not been identified.

Legionnaires’ disease is a type of pneumonia (lung infection). It is important to note that Legionnaires’ disease symptoms are similar to those of COVID-19 and other respiratory illnesses such as the flu. Symptoms can include fever, chills, cough, shortness of breath, chest pain, muscle aches, and headache. If Legionnaires’ disease is suspected, only tests ordered by a doctor can confirm the diagnosis. Although Legionnaires’ disease is a serious illness, it is treatable with antibiotics.

As it can take up to two weeks for symptoms to develop, NJDOH recommends that those who develop these symptoms within two weeks of visiting Middlesex or Union county seek medical attention.

“Early diagnosis is key to effectively treating Legionnaires’ disease,” said Acting Health Commissioner Dr. Kaitlan Baston. “Although the risk of contracting Legionnaires’ disease if you live in or have recently visited Middlesex or Union counties remains low, individuals who develop pneumonia-like respiratory symptoms should visit their health care provider immediately to be evaluated.”

It is rare for healthy people exposed to Legionella to develop Legionnaires’ disease. However, people over the age of 50, especially those who smoke, or those with certain medical conditions, including weakened immune systems, chronic lung disease, or other chronic health conditions, are at increased risk for Legionnaires’ disease if exposed to Legionella bacteria.

Legionnaires’ disease is not transmissible from person to person. People can get Legionnaires’ disease by breathing in aerosolized (small droplets of) water containing Legionella bacteria. Aerosolized water can come from cooling towers, hot tubs, cooling water misters, decorative fountains, and plumbing systems. Home air conditioning units (either central or in-window) do not use water to cool and are not a risk for Legionella growth. In rare instances, individuals may also become sick when water containing Legionella is aspirated into the lungs while drinking (“goes down the wrong pipe”), particularly among those with swallowing difficulties.

Cooling tower systems are commonly found in large places like public buildings, offices, commercial spaces, universities, hospitals, community centers, and industrial sites. Cooling tower systems help remove heat from building’s processes like air-conditioning, refrigeration, and industrial manufacturing. If these systems aren't well maintained, they can release water droplets containing Legionella into the air, putting people in the area at risk of exposure.

NJDOH advises that cooling tower system owners and operators review their water management and maintenance plans to reduce the risk of Legionella growth and spread. They should work with their water treatment consultants to test their cooling tower systems for Legionella bacteria. Cooling tower systems that test positive for Legionella should be remediated following CDC’s guidelines. It is strongly recommended to always maintain biocide (chemical) levels in the circulating water, even during low-use periods. If a cooling tower system hasn’t been cleaned and disinfected within the last 12 months (or more frequently if recommended by the manufacturer), then it should be scheduled immediately. More guidance is available on CDC’s website.

NJDOH receives approximately 250-375 reports of Legionnaires’ disease each year and works closely with local health departments to investigate potential sources of infection. Investigations can be lengthy and identifying the exact source is often challenging. Any potential sources found will be addressed and remediated to prevent further transmission.

For more information, visit the NJDOH website.

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Last Reviewed: 11/8/2023