The Centre for Health Protection is investigating a case of Legionnaires' disease affecting a 67-year-old man.
He fell ill on July 5 and went to Queen Elizabeth Hospital on July 7.
He was transferred to intensive care on July 9.
The clinical diagnosis is pneumonia and he is now in critical condition.
He tested positive for the Legionella pneumophila serogroup 1 antigen.
He has no recent travel history and his home contact is asymptomatic.
