What are Listeria bacteria?
Listeria are a naturally occurring bacteria, that live generally harmlessly in the soil, water and natural environment. However, Listeria do have a species that is dangerous to our health, known as Listeria monocytogenes.
Listeria monocytogenes is a gram-positive, rod-shaped bacterium, and are most infamous for surviving and even growing well in refrigeration temperature ranges. This bacterium affects foods such as raw chicken, dairy, processed (deli) meats as well as smoked seafood. This bacteria can also survive in oxygen-poor conditions, meaning even vacuum-packed foods are not free from concerns.
This Listeria monocytogenes bacterium is known as an opportunistic pathogen, meaning those that are already ill or have a low immune system are most likely to suffer from an infection.
Listeria monocytogenes is a food-borne illness-causing bacteria. The disease is known as Listeriosis. Listeria monocytogenes is often isolated in cattle, sheep, and fowl, and is also found in dairy products, fruits, and vegetables.
What are the Symptoms of Listeria Infection?
A person with Listeriosis usually has a fever, muscle aches, and gastrointestinal symptoms such as nausea or diarrhoea. If the infection spreads to the nervous system, symptoms such as headache, stiff neck, loss of balance, confusion or convulsions can occur. With brain involvement, Listeriosis may mimic a stroke.
Infected pregnant women will ordinarily experience only a mild, flu-like illness; however, infection during pregnancy can lead to miscarriage, infection of the newborn or even stillbirth. Pregnant women are about 20 times more likely than other healthy adults to get Listeriosis.
How to Prevent a Listeria monocytogenes Infection?
General recommendations include:
- Cook raw food from animal sources completely
- Keep raw meats separate from vegetables and ready-to-eat foods
- Avoid unpasteurised (raw) milk or foods made from unpasteurised milk
- Wash hands, knives, and cutting boards after handling uncooked foods
- Wash raw vegetables thoroughly before eating
- And consume perishable and ready-to-eat foods as soon as possible.
Recommendations for persons at high risk, such as pregnant women and persons with weakened immune systems include:
- Do not eat soft cheeses (such as feta, Brie, Camembert) unless they have labels that clearly state they are made from pasteurised milk.
- Don’t eat hot dogs or deli meats, unless they are reheated until hot.
- Wash hands after handling these products.
- Do not eat meat spreads or smoked seafood from the refrigerated or deli section of the store.
The Listeriosis Outbreak in South Africa Preview
We know that raw meats, especially chicken are almost always synonymous with the presence of L.mono. This is generally not a concern, as raw meats are not sterile and it would not be realistic to expect them to be, due to the nature of the product. This may not be a concern for the manufacturing industry but could be a problem for home consumers.
We know from ongoing food poisoning outbreaks, that food safety in the home is always at an acceptable standard, and the potential for cross-contamination and poor hygiene is high. Therefore L.mono has a great opportunity to establish itself in the fridge and kitchen.
The Science Behind An Outbreak Preview
When a food-borne disease outbreak is detected. Such as the Listeriosis outbreak in South Africa. Health officials and scientists work quickly to collect as much information as possible to find out what is causing it. So they can take action to prevent more people from all ill.