Durban
According to a BBC report, Root stayed at the team hotel while players rehearsed in Port Elizabeth for the match which starts on Thursday.
England's tour to South Africa has seen many players getting affected by illness with Rory Burns and James Anderson ruled out with injuries.
Ollie Pope, Chris Woakes and Jack Leach were ruled out of the 107-run first-Test defeat in Centurion, while Root, Jos Buttler and Ben Stokes spent time off the field.
The four-match series is locked 1-1 after England's 189-run win in Cape Town.
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