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Listeria – what you need to know

What is listeriosis?

Listeriosis is a serious bacterial disease caused by Listeria monocytogenes. It is transmitted to people by eating contaminated food. It is a serious illness with high fatalities (deaths) ranging from 20 – 30% in severe cases. It can be treated with antibiotics.

Who is at risk?

Anyone can get listeriosis but certain groups are at risk of developing complications (the more serious kind) of the disease. These are:

  • Pregnant women and their unborn babies
  • New born babies and small children
  • The elderly (over 65 years)
  • People with conditions such as diabetes, cancer, chronic liver or kidney disease
  • People with weakened immune systems due to HIV or chemotherapy

What are the signs and symptoms of listeriosis?

Most people who eat food contaminated with listeria will not get sick. People who do get sick with listeriosis will usually have mild flu-like symptoms such as fever, muscle pain, feeling tired and sometimes nausea or diarrhoea. In the at-risk groups mentioned above, the infection can spread to the nervous system which can cause meningitis leading to headaches, confusion, stiff neck, loss of balance or convulsions. In pregnant women, it can lead to premature births, infection of the new born with permanent disability, and miscarriage or stillbirth. Symptoms usually appear between 3 days and 3 weeks of eating contaminated food.

What has happened with listeriosis in South Africa?

Normally there are about 30-60 cases of listeriosis a year in South Africa. But there is currently a huge outbreak: over 900 cases have been reported and 180 people have died. Cases have been reported from all 9 provinces, but most have been in Gauteng. According to the World Health Organization, this is the largest ever outbreak of the disease.

Ready-to-eat, processed meat – specifically polony and viennas made at two production plants (Enterprise in Polokwane and Rainbow in Germiston) – have been identified as the possible source of the outbreak. The Department of Health has therefore warned the public not to eat polony, viennas or ready-to-eat meats from these companies and to return these products to the shops. Most supermarkets (Checkers, PicknPay, Woolworths) are offering a full refund on these products.

What should we do?

Do not eat or feed your children or your organisation’s beneficiaries polony, viennas or ready-to-eat meat (like salami, ham, pastrami etc). Particularly if your beneficiaries are pregnant women, small children, the elderly or people living with HIV. Remove all these products from your fridges and clean your fridges and food preparation equipment with soapy water followed by a mild solution of bleach (1 teaspoon of Jik to 1 litre of water). Return the products to the shop where you bought them for a refund.

If you or those you care for develop symptoms and you think you may have eaten contaminated food, go to your doctor or clinic immediately. If the doctor suspects listeriosis they will test you for it and start you on treatment.

How can I prevent it?

Unlike most other food-born germs, Listeria monocytogenes can grow in refrigerated foods. However, cooking food destroys Listeria. Those at high risk of listeriosis should avoid the following foods:

  • Raw or unpasteurized milk, or dairy products
  • Soft cheeses (e.g. feta, goat, Brie)
  • Foods from deli counters (e.g. prepared salads, cold meats) that have not been cooked or properly heated
  • Refrigerated pâtés

The main way to prevent becoming sick with listeriosis is to follow good basic hygiene which is:

  • Use only pasteurized dairy products
  • Thoroughly cook raw foods from animal sources, such as beef, pork or poultry
  • Wash your hands before preparing food, before eating and after going to the toilet
  • Wash kitchen surfaces and utensils regularly, particularly after preparing raw meat, poultry and eggs
  • Wash raw vegetables and fruits thoroughly before eating.

This information was adapted from the National Institute of Communicable Diseases Listeriosis Guide for Healthcare Workers