Listeria outbreak: Why your back-to-school lunch box staples may be dangerous

South Africa’s ongoing spate of listeria cases has claimed more than 60 lives in what the World Health Organisation (WHO) is now calling the world’s biggest outbreak of the food-borne illness, according to an podcast interview with WHO spokesperson Christian Lindmeier recorded by the United Nations News Centre.

Listen: “SA is experiencing the largest outbreak of listeria ever reported worldwide”

Listeria is caused by the bacteria Listeria monocytogenes, which occurs naturally in soil, water, plants and the faeces of some animals. The bug’s ability to make its home in so many different places means few foods are above suspicion as the National Institute for Communicable Diseases (NICD) continues to try to trace the source of the outbreak that has now hit all nine provinces.

Since the national body first reported a spike in patients with listeria in October, about 750 laboratory-confirmed cases have been recorded largely among people with compromised immune systems.

Although most people who eat listeria-infected food will not get sick, people with weaker immune systems caused by, for example, HIV, diabetes or chemotherapy, are at risk. Pregnant women are also more susceptible to the disease as are newborn babies who can contract it from their mothers in the womb.

Almost 40% of cases in South Africa have occurred among children younger than one month.

But older, school-going children, whose bodies are better equipped to fight off diseases because their immune systems are more developed, made up only 4% of the cases, says Juno Thomas, head of the NICD’s Centre For Enteric Diseases. The unit studies viruses and bacteria that affect the intestines.

You cannot contract listeria by touching people who carry the bacteria, the NICD emphasised in a statement.

In the meantime, here are three habits you can adopt to limit your family’s chances of contracting listeria.

1. Give those counters and hands an extra scrub

Listeria monocytogenes is a stubborn organism, says Thomas.

She explains: “Once the bacteria settles on a surface, it produces a layer of slime that sticks it down firmly.”

Parents and guardians should make sure to clean kitchen surfaces and hands properly before preparing food. Everyone should wash their hands before eating. 

It’s not just the kitchen counter that could do with a scrub, Thomas says. WHO food safety guidelines recommend knives and forks, cutting boards, and drying cloths should be cleaned with boiling water and a sanitising agent like bleach. This helps to avoid cross contamination or prevents bacteria from being transferred between objects, such as from a dirty cutting board to freshly prepared vegetables.

If your child reaches for their favourite fruit, encourage them to wash the fruit thoroughly. The same goes for vegetables.

2. Get cooking more often

Until the NICD knows more, meat, poultry, dairy and produce such as fruit and vegetables could all be likely culprits fuelling the listeria outbreak and that includes ready-to-eat products and lunchbox staples such as viennas, polony and cold meat. 

Because the bacteria can survive in fridge and even freezer temperatures, any meat should be cooked to decrease the risk of infection, a NICD statement warns.

3. Watch out for these symptoms

Symptoms of a listeria infection can start to show anywhere between six hours and 70 days after eating contaminated food, Thomas says.

Most children with healthy immune systems won’t get sick. If they however do, they’re likely to develop symptoms of gastroenteritis such as fever and diarrhoea, which will typically pass without the need for medical attention.

But in more severe cases – which mostly occur in people with weakened immune systems – the bacteria can cause blood poisoning or bacterial meningitis, a potentially deadly inflammation of the tissue surrounding the brain and spinal cord.

A fever, severe headaches, sensitivity to light and confusion can all be signs of bacterial meningitis and could require emergency care, says the United States medical research nonprofit the Mayo Clinic.

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Joan van Dyk
Joan Van Dyk
Joan van Dyk graduated with an honours degree in journalism from Stellenbosch University in 2017. She was the top performing student in the class of 2016.

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