Inquiries continue into the source of the illness, which is clustered around the Heads of the Valleys corridor.

The focus is on industrial premises and large air conditioning systems.

"Most of the cases of Legionnaires' disease that are notified to us are isolated cases, but outbreaks can occur.

"People become infected when they inhale Legionella bacteria which are spread through the air in the form of a fine mist or droplets from a contaminated water source.

"Legionnaires' disease cannot be passed from person to person."

Legionnaires' disease begins with flu-like symptoms and can lead to pneumonia, usually in adults.

Anyone worried about their health should contact their GP.

The councils involved in the investigation include Cardiff, Merthyr Tydfil, Rhondda Cynon Taf, Caerphilly, Blaenau Gwent, Torfaen and Monmouthshire.

The outbreak control team, which also includes representatives from Cwm Taf Health Board, Aneurin Bevan Health Board, and Cardiff and Vale University Health Board, will continue to monitor the situation closely.

(Read More) Source: BBC News