Health Minister Dr Aaron Motsoaledi announced on Tuesday morning that while Listeriosis is a serious disease, it can be treated with antibiotics.
The department has not found the origin of the outbreak but suspects food contamination at the source, such as farms or food processing plants.
Motsoaledi said the cause of the outbreak was now being investigated and urged South Africans to wash their hands and keep food at safe temperatures.
"The source of this outbreak is now being investigated, and all the stakeholders are cooperating with the investigation led by the NICD (National Institute for Communicale Diseases)", he said.
Health Minister Dr Aaron Motsoaledi called on South Africans to be vigilant and immediately report flu-like symptoms including diarrhoea, fever, general body pains and weakness at the nearest hospital. This triggered a review of all cases diagnosed in both public and private hospitals.
Out of the 557 cases reported, 345 cases were reported in Gauteng, followed by the Western Cape which reported 71 cases, and 37 cases of Listeriosis reported in KwaZulu-Natal.
Motsoaledi further explained that they concluded that the disease was an outbreak when it reached 500 cases.
Dr Rufaro Chatora, country representative of the World Health Organisation, said the the global body is "satisfied" that since the outbreak was detected, South Africa has been following set procedures as set in the worldwide health regulations. "The remaining 18% is distributed in the remaining six provinces‚" Motsoaledi said.
People usually contract it through animal products and fresh fruits and vegetables.