The death toll from an outbreak of the food-borne disease listeria in South Africa has more than doubled from previous numbers given in January. The outbreak has now claimed 172 lives. And 915 laboratory-confirmed cases have been reported to the National Institute of Communicable Diseases. CGTN's Yolisa Njamela has the story.

Listeriosis is caused by a bacterium found in soil, water and vegetation. It can contaminate a wide variety of food types, including meat and meat products, dairy products. This is the worst outbreak recorded in South Africa.

DR. JUNO THOMAS NATIONAL INSTITUTE OF COMMUNICABLE DISEASES "This is extremely concerning, not only is it the largest listeriosis outbreak that our country has ever experienced but it is now the largest outbreak of confirmed cases anywhere in the world. So the concern is that despite intensive investigation for many months now, the cause of the outbreak, the source of contaminated food has still not been identified, however, there're numerous leads being followed at the moment."

South Africa's economic hub, Gauteng remains the hardest hit province with fifty-nine percent of laboratory-confirmed cases. Health authorities say babies, pregnant women and those with compromised immune systems like the elderly or those infected by HIV, are most at risk.

DR. JUNO THOMAS NATIONAL INSTITUTE OF COMMUNICABLE DISEASES "The apparent sudden increase in the number of deaths reported is just because we are getting more and more data every day on what happened to all of the patients that were admitted to hospital during last year and we expect that with the listeriosis outbreak of the size and severity that we are seeing, that anywhere between twenty and thirty percent of patients are likely to die."

The National Institute for Communicable Diseases is the leading the hunt for the cause of the outbreak.

DR. JUNO THOMAS NATIONAL INSTITUTE OF COMMUNICABLE DISEASES "In the meantime, what the public should do is follow the world health organizations five keys to safer food. These are basic commandments that everyone should be aware of and following as a matter of routine every day because they protect us against food borne diseases in general of which there are many. Obviously our focus right now is listeriosis.

Listeriosis can cause flu-like symptoms, stiff neck, confusion and convulsions. In pregnant women, it can cause stillbirths, miscarriages or premature delivery. The bacterium is treated with antibiotics.

YOLISA NJAMELA JOHANNESBURG, SOUTH AFRICA "The National Institute for Communicable Diseases says it remains optimistic that the source of this outbreak will be found, and urged members of the public not to panic. Yolisa Njamela, CGTN, Johannesburg, South Africa."