The Centre for Health Protection is investigating a case of Legionnaires' disease involving a 58-year-old man.
He fell ill on April 9 and was admitted to Alice Ho Miu Ling Nethersole Hospital and tested positive for the disease.
He is in stable condition.
He has no recent travel history and his home contacts are asymptomatic.
It is the sixth case reported this year. There were 28 cases each in 2013 and 2012.
