What is Legionnaires' disease? Deadly outbreak prompts health alert in Sydney CBD - Check causes, symptoms and high-risk age groups

A Legionnaires’ disease outbreak has prompted a health alert in Sydney’s central business district, with authorities urging people to remain vigilant for symptoms. A fourth case of the potentially deadly Legionnaires’ disease has been confirmed in Sydney, prompting health authorities to issue a fresh alert, reported 9News. The warning follows a rise in infections earlier this week, with three additional cases reported Sunday. According to 9News, all four people linked to the cluster had spent time in the Sydney CBD, specifically around Clarence Street near Wynyard, between December 9 and December 18.

Investigations are continuing to determine the source of the outbreak, with health authorities advising anyone who was in the affected area during the specified period to monitor for symptoms and seek medical attention if they feel unwell. Speaking on Sunday, Professor Mark Ferson, acting director of the local health district’s public health unit, said the source had not yet been identified and that it was still possible the reported cases were not linked, according to The New Daily.

WHAT IS LEGIONNAIRES' DISEASE?

Legionnaires’ disease is a severe form of pneumonia caused by breathing in water droplets contaminated with Legionella bacteria and does not spread from person to person. People who are infected can begin to show symptoms anywhere from two to 10 days after exposure and may include fever, chills, cough, shortness of breath, muscle aches, and headaches. In more serious cases, the illness can lead to severe chest infections and require hospital treatment.

Legionnaires’ disease outbreaks can occur when Legionella bacteria from environmental sources, such as soil or cooling towers on top of large buildings, become contaminated. According to The New Daily, NSW Health said it is working closely with the City of Sydney to test and inspect cooling towers in the affected area.

Health experts warned that certain groups are more vulnerable to severe illness.

"Those most at risk include elderly people, people with underlying lung or other serious health conditions, and smokers," Dr Vicky Sheppeard said as quoted by 9News.