Anglicare announced the positive test this morning.
The staff member was working exclusively in the COVID-19 positive area of the facility, after residents without the virus were moved to different areas of the building last week.
“It is our understanding that this staff member was asymptomatic,” Anglicare said in a statement.
“The positive test result was discovered during our now daily, rigorous testing regime which is now being applied to all staff working at Newmarch House.”
The carer is now self-isolating.
There are now 64 cases of coronavirus linked to Newmarch House.
Fifteen residents have died, including a 71-year-old man whose death was announced on Monday afternoon.
The latest fatality takes Australia’s death toll to 96.