The timing of the illness is another blow for Eddie Howe, who is already dealing with a mounting injury list at St James' Park.
Guimaraes has not featured since February 10, and his period in isolation will further delay his return to training as the club look to navigate a difficult run of results in the Premier League.
With the Magpies struggling for form following their heavy European exit and the derby loss to Sunderland, Howe will be desperate to get his midfield talisman back into the fold.
For now, the Brazilian remains confined to his home, focusing on a recovery that Newcastle fans hope will be swift amid the swirling rumours of a high-profile summer transfer.