British agent Intermusica confirmed on Thursday that the violist and conductor was in isolation in an Adelaide hospital with the COVID-19 illness.
He was to perform with the Adelaide Symphony Orchestra in a Beethoven concert at the annual Adelaide Festival on Saturday.
Festival executive director Rob Brookman says Dean canceled his appearance at the festival due to pneumonia-like symptoms.
Brookman says three people who had been in contact with Dean have self-quarantined.
The 58-year-old Australian has performed with the Berlin Philharmonic Orchestra and Taiwan's National Symphony Orchestra.
Taiwan's CDC statement said the patient was a composer who had concerts in Taiwan Feb. 28 and March 1 without identifying Dean by name.