Harris, who played eight county championship matches for Warwickshire this year, has replaced fellow slow left-armer Nicky Boje, who announced his retirement from international cricket last week despite being selected for the first Test against India.
Wrist-spinner Paul Adams and batsman Jacques Rudolph, both of whom were released for domestic action last weekend, remain in the 15-man squad, while uncapped paceman Morne Morkel has been placed on standby for the injured Dale Steyn and Andrew Hall.
''We needed someone to replace Nicky Boje and I initially went to Claude Henderson but he indicated he was not available,'' selection convenor Haroon Lorgat told reporters today.
Henderson is also an orthodox left-arm spinner, who played seven Tests for South Africa between 2001/02 and 2002/03, but he has indicated he does not wish to risk his status as a local player with Leicestershire.
''Paul Adams is the only wrist spinner in South Africa with any sort of record but he has been brought in as the 15th member of the squad and I have no doubt he has some way to go to make the starting XI,'' Lorgat added.
The 28-year-old Harris, who plays for the Titans franchise in South Africa, has taken 17 wickets in four SuperSport Series matches this season at an average of 27.94.
South Africa, who were bowled out for 84 in their first innings en route to losing the first Test by 123 runs, could also shuffle their batting order following the continued failure of openers Herschelle Gibbs and Graeme Smith.
''The opening pair definitely need some runs and we are going to have to talk hard about top-order alternatives in Durban,'' Lorgat said.
Squad: Graeme Smith, Herschelle Gibbs, Hashim Amla, Jacques Kallis, Ashwell Prince, AB de Villiers, Mark Boucher, Shaun Pollock, Andre Nel, Makhaya Ntini, Dale Steyn, Jacques Rudolph, Andrew Hall, Paul Harris, Paul Adams, Morne Morkel (on standby).