The source of the unique strain of listeria that has caused the world’s biggest documented listeriosis outbreak has finally been revealed. Here are seven things you need to know about Listeria and the outbreak:

1. Enterprise Foods Polokwane factory has a serious problem with food safety

Inspectors from the municipality‚ department of health and agriculture and three experts from the World Health Organisation went to this factory on February 2 and took over 300 samples from it.

But about 100 samples‚ or 30%‚ tested positive for others strain of listeria monocytogenes: a bacteria that can cause food-borne illness.

Head of the Centre for Enteric Diseases at the National Institute for Communicable Diseases (NICD)‚ Dr Juno Thomas‚ said there should not be any listeria in a factory that produces processed meat‚ as the products can so easily be contaminated with this bacteria.

2. The case against Enterprise’s Polokwane Factory is rock solid

While Tiger Brands – which owns Enterprise Food – said it was awaiting its own results to confirm the type of strain of listeria it found in its Polokwane factory‚ the NICD has built a firm case against it.

The ST6 strain – linked to the outbreak – was found in the factory by the NICD and in Enterprise polony eaten by children at a creche who became ill and developed listeriosis. Of 109 patients with the disease interviewed by the NICD‚ 85% reported eating ready-to-eat meat such as polony and sausages‚ adding to the evidence the NICD needed.

3. You don’t need to panic if you have eaten polony

Listeriosis affects people with weakened immune systems‚ the elderly‚ pregnant women and babies in the womb or infants who contract it from their mothers during birth. Head of the outbreak response team at the ‎NICD, Dr Kerrigan McCarthy, urged people not to panic.

“The vast majority of people who consumed these products will in fact be fine. There is absolutely no reason to worry.”

She elaborated‚ saying: “In the absence of symptoms‚ one should not worry. If someone with a weakened immune system has consumed these foods and developed stomach problems or fever and diarrhoea‚ go to the doctor and be tested.”

4. Listeria loves your fridge

Listeria can continue to multiply in uncooked food kept in the fridge. This is why processed meats‚ smoked meats and soft cheeses that are not cooked are often linked to outbreaks.

The NICD recommended the use of diluted bleach to clean areas where you may have kept viennas or polony.

5. Cooking kills the listeria bacteria

Food should be heated above 70 degrees Celsius as heat kills the listeria bacteria.

Cooked food must be kept separate from raw food and utensils used on raw food must not touch cooked food‚ in order to avoid cross-contamination.

6. Listeria can be very difficult to find in food processing plants

The microscopic bacteria can live in nooks and crannies in factories and it can survive cleaning with detergents‚ said Professor Lucia Anelich‚ a food consultant.

The bacteria is not spread homogeneously through food so scientists can test one slice of polony and find nothing‚ then test another slice and find the bacteria.

7. Food safety is the responsibility of local government

Health inspectors‚ now called environmental health inspectors‚ do spot checks at food facilities. They are employed by local government. But many understaffed‚ overwhelmed municipalities do not hire or prioritise health inspectors‚ said Health Minister Aaron Motsoaledi. He wants to change the Constitution to remove this power from local government.