TTwo patients died after contracting a fungal infection linked to pigeon droppings in a hospital.
NHS Greater Glasgow and Clyde (NHSGCC) launched an investigation into the death of a patient at the Queen Elizabeth University Hospital in Glasgow, with the cause still to be determined.
The health council said the second affected patient – who was elderly – died of an unrelated problem.
Control measures were immediately implemented after the two cases of Cryptococcus were detected.
A spokesman said: "Our thoughts are with families at this distressing time.
"Due to patient confidentiality, we can not share more details of the two cases.
"The organism is harmless to the vast majority of people and rarely causes disease in humans."
The infection is caused by the inhalation of the fungus Cryptococcus, found mainly in the soil and excrement of pigeons.
The NHSGCC said a likely source was found in a non-public area away from the wings and excreta were removed.
The health council said that a small number of children and adults who are vulnerable to infection are receiving medication and this has proved effective.
Teresa Inkster, the NHSGCC's chief infection control consultant, said: "Cryptococcus lives in the environment around the world. It rarely causes infection in humans.