A common mould has killed two people, and left four others seriously ill, at one of Sydney’s largest hospitals.

Health authorities are investigating a cluster of fungal infections at the Royal Prince Alfred Hospital’s transplant unit.

Six patients developed infections between October and December 2025 after being exposed to Aspergillus, a common mould found in soil, plants, dust and damp environments.

In a statement, a hospital spokesperson suggested the mould may have been present at nearby construction sites, part of the hospital’s A$940 million redevelopment.

So what is Aspergillus? And should you be concerned?

Yes. Aspergillus moulds are a type of filamentous fungi, meaning they form long chains, and are usually found in soil, plants and damp areas.

This type of mould is usually harmless to healthy people. But it can cause a severe respiratory disease called aspergillosis. Aspergillosis affects about 250,000 people around the world.

How can Aspergillus harm?

This type........

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