The provincial health authority in the South African province of Gauteng revealed 19 new cases of cholera, including 10 deaths, in Hammanskraal on Sunday.
South Africa recorded its first cholera fatality in February, shortly after the virus arrived from Malawi.
It was unknown how many cases there were nationwide as of Sunday, but Gauteng, which includes Johannesburg and Pretoria, has been hardest impacted.
It is caused by contaminated food or water and can cause severe diarrhoea, vomiting, and weakness. If left untreated, it can kill within hours.
The last outbreak in South Africa was in 2008/2009, when about 12,000 cases were reported following an outbreak in neighbouring Zimbabwe, which led to a surge of imported cases and subsequent local transmission.