New York City health officials have declared a Legionnaires' disease outbreak on Manhattan's Upper East Side, with 23 confirmed cases and 17 hospitalisations recorded as of 6 July. No deaths have been reported. Officials are urging anyone who has visited the east side of Central Park or the Upper East Side since late June to watch for symptoms, warning that early detection is crucial to avoiding life-threatening complications, particularly among high-risk groups.

Investigators believe contaminated cooling towers are the likely source and have stressed that the illness does not spread from person to person and is not linked to the city's drinking water. Legionnaires' is a form of pneumonia caused by Legionella bacteria, which thrive in stagnant water systems such as cooling towers, plumbing and hot tubs; people become infected by inhaling or swallowing contaminated water droplets. Symptoms typically appear two to 14 days after exposure, and those over 50, smokers and people with chronic lung conditions face the greatest risk. Health Commissioner Dr Alister Martin said the disease is deadly but treatable if caught early.