A small number of cases of Legionnaires' disease have been identified in Rotherham following a higher-than-usual number of reports over the past month.
The UK Health Security Agency is working with Rotherham Council and other partners to establish whether the cases are connected and whether there is a common source.
Officials have stressed that the overall risk to the wider public is low, and that Legionnaires' disease is not usually passed from person to person.
The illness is normally contracted by breathing in droplets of water containing legionella bacteria.
Symptoms can include a high temperature, a cough, shortness of breath, chest pain or discomfort, and flu-like symptoms.
Anyone experiencing symptoms is being advised to contact NHS 111 or their GP.
The investigation remains ongoing.
Source information
Source: UK Health Security Agency, Rotherham Council