"This is a dreadful tragedy in the true sense of that word," said Cricket South Africa (CSA) chief executive Thabang Moroe. "This is devastating news for all of us.
"Elriesa did so much for the community in which she lived and gave excellent service both as a national player and in the work she did at grassroots level.
"On behalf of the CSA family, I extend our deepest sympathy to her husband, her family, friends and all her cricketing colleagues."
Elriesa Theunissen-Fourie last appeared for South Africa against Bangladesh in the home series in 2013.
Provincially, she represented the North West Dragons and was very active at grassroots level, coaching at the local community hub until she had to take maternity leave ahead of the birth of her first child.