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Two treks through the mountains and one day in Padova were all that separated Spratt from a potential place on the podium, having sat sixth through seven stages with her preferred terrain still to come.
Instead, the Australian's recovery tour will now take a brief hiatus, as will teammate Georgia Baker, who was ruled out after being deemed a close contact.
"My Giro is over," Spratt said on Twitter. "I felt a bit off in the stage yesterday and woke up this morning not feeling well.
"A test confirmed positive for Covid. So sad and disappointed when my favourite stages were finally here. Heading home and will focus on recovery."
It remains to be seen whether Spratt will compete at the Tour de France Femmes, though it appears form certainly won't be a concern judging from the 34-year-old's performances in Italy.
Spratt delivered podium places in 2018 and 2019 respectively, before bowing out of the following two editions due to injury.