With back to school in full swing and the listeriosis outbreak still continuing, there is a lot of news out there - but misinformation can spread panic. So here is some practical information to help parents, teachers and preschools.
Some facts about listeria:
- Listeria monocytogenes is a bacterium is widely distributed in nature and can be found in soil, water and contaminated food. Animals and food products such as vegetables can become contaminated from these sources.
- This bacterium causes Listeriosis which usually results in gastro-enteritis with symptoms ranging from mild to severe. However, in persons with weak immunity, Listeriosis can lead to meningitis or septicaemia. In pregnant women, Listeriosis may results in pregnancy loss (abortion) along with meningitis of their infant.
- The incubation period varies and can be between 3 – 70 days but in most cases is 21 days. In the average healthy adult, infection is usually asymptomatic – you don’t even know you have had it.
- Symptoms are usually mild and may include fever, myalgia, malaise and sometimes nausea or diarrhoea. In at-risk patients, spread of infection to the nervous system can cause meningitis leading to headaches, confusion, stiff neck, loss of balance or convulsions.
- Pregnant women may present with mild flu-like illness associated with headache, fever and myalgia. However, infections during pregnancy can lead to premature births, infection of the newborn with permanent disability, and miscarriage or stillbirth.
How is Listeriosis diagnosed?
- A simple blood test can be used.
How is Listeriosis treated?
- Gastro-enteritis due to Listeria usually does not require treatment and can be treated symptomatically with fluids.
- Meningitis or septicaemia due to Listeria can be life threatening and should be treated with intravenous antibiotics.
How can Listeriosis be prevented?
- Unlike most other foodborne pathogens, Listeria monocytogenes can grow in refrigerated foods that are contaminated. To prevent this, it is recommended to have fridge temperatures below 4 o C; and freezer temperatures below -18o C.
Those at high risk of listeriosis should avoid the following foods:
- Raw or unpasteurized milk, or dairy products that contain unpasteurized milk;
- Soft cheeses (e.g. feta, goat, Brie);
- Foods from delicatessen counters (e.g. prepared salads, cold meats) that have not been heated/reheated adequately;
- Refrigerated pâtés.
Is there a vaccine?
- There is no vaccine or pre-exposure medications for preventing infection.
What can you do as a parent/school teacher/pre-school owner?
The main preventive measure is to always ensure that good basic hygiene is followed. This includes:
- Using only pasteurized dairy products;
- Thoroughly cooking raw foods from animal sources, such as beef, pork or poultry;
- Washing your hands before preparing food, before eating and after going to the toilet;
- Washing and decontamination of kitchen surfaces and utensils regularly, particularly after preparing raw meat, poultry and eggs, including industrial kitchens;
- Washing raw vegetables and fruits thoroughly before eating
For more information on the Listeria Outbreak and associated news, Food Focus has a dedicated page:
References: Information adapted from the NICD website