Why Listeria Keeps Sneaking Into Food – And How to Protect Yourself from Listeriosis
It seems that in recent years, we frequently encounter news of product recalls and restaurant closures due to concerns about bacterial contamination. One of the most recent recalls involved goat cheese¹, prompted by a notification from the European Rapid Alert System for Food and Feed about a listeria risk. In the United States, listeria has triggered even more recalls, affecting products ranging from deli meats to frozen waffles².
But what exactly is listeriosis, and how does it get into our food? Find the answers to these questions in our article, and learn how to protect yourself and your loved ones from this potentially serious illness.
What is listeriosis?
Listeriosis, or a listeria infection, is a foodborne illness caused by the bacteria Listeria monocytogenes. It is a potentially life-threatening illness, posing even greater risks to the elderly, pregnant women, and individuals with compromised immune systems³. The incidence of listeriosis increases in people over 50 years of age. If left untreated, listeriosis can lead to complications such as meningitis, blood infections, foetal loss, and even death.
What are the symptoms of listeriosis?
Mild cases of listeriosis are typically accompanied by flu-like symptoms:
- Fever
- Chills
- Nausea
- Diarrhoea
- Muscle aches
However, when listeria spreads to the central nervous system, it can lead to meningitis, which may present with the following symptoms:
- Severe headache
- Stiff neck
- Sensitivity to light (photosensitivity)
- Confusion
- Loss of balance
- Seizures
Listeriosis symptoms can take anywhere from a few days to over 30 days to show up. (Incubation period). This depends on the host immune system and the load of contamination.
How dangerous is listeriosis?
Generally, healthy individuals rarely become severely ill due to listeria infection. However, certain populations, including the elderly, pregnant women, immunocompromised individuals, and newborns, are more susceptible to developing serious illness. As a result, foodborne listeriosis is considered one of the most dangerous foodborne diseases despite its relative rarity, Mortality rate ranging from 20% to 30%³ can be seen in certain high risk populations.
What causes listeria infections?
Listeriosis is caused by Listeria monocytogenes, or listeria for short. This bacteria is commonly found in nature, including in soil, groundwater and animal faeces. Listeria enters the body through the consumption of contaminated food, initially affecting the gastrointestinal tract as it passes through (although not everyone infected with listeria will experience them). If the bacteria invade the intestinal lining, they can enter the bloodstream, spreading throughout the body, leading to other complications.
How does listeria get into our food?
Listeriosis can occur when listeria contaminates the food we eat, such as vegetables, meats or other food products. In the case of processed foods—those that have been modified from their original state to preserve, prepare or package them—listeria can enter undetected through various stages of the food supply chain. As our food supply becomes more complex, the risk of listeria contamination increases, especially with ready-to-eat foods. These foods, such as pre-packaged items kept in cold storage⁴, provide additional opportunities for listeria contamination with the slightest breach in food safety practices. Furthermore, the long shelf life of these products allows the bacteria more time to grow and multiply.
Some common foods⁵ that are more likely to harbour listeria include:
- Unpasteurised dairy products
- Raw or undercooked meat, poultry and seafood
- Refrigerated, smoked seafood
- Deli meats and hot dogs
It is essential to note that listeria can potentially be found in almost any type of food, although commonly associated with certain foods prone to bacterial growth.
What should I do if I own a product recalled due to listeria?
Contaminated products are often urgently recalled to prevent listeria from spreading and affecting large populations. As such, they must be removed from the food supply as soon as possible, even if it’s just a precautionary measure. If you have an item that has been recalled, make sure to discard it and disinfect any surfaces that may have been exposed to it to eliminate the risk of further contamination.
What else can I do to prevent listeriosis?
Practising good food safety and hygiene is one of the best defences against listeriosis. For fresh foods, keep them at the right temperature and make sure to refrigerate or freeze perishable items, such as meats and dairy products, promptly. It’s also crucial to keep your hands and the surfaces that come into contact with food clean to prevent cross-contamination. Washing raw vegetables before cutting or consuming them is integral, as it helps to remove any bacteria present.
Individuals at higher risk of listeriosis should be extra cautious when consuming foods that are more prone to contamination with listeria. Properly cooking foods to a safe temperature using a food thermometer can help reduce the risk of listeriosis, as sufficient heat, specifically above 50°C⁶, can kill listeria. High risk individuals (especially pregnant, immunocompromised) should not consume un pasteurised dairy products, undercooked, raw meats.
Is there treatment for listeriosis?
Listeriosis can be treated with antibiotics, although this is typically used for more serious infections. Mild listeria infections of healthy individuals may resolve on their own without the need for antibiotics. Penicillins or sulphur drugs⁵, either alone or in combination, can be used for treatment of more severe cases.
Contact our specialists at ID Specialists for more information on listeriosis.
References
- Mujibah F. Three types of goat cheese products recalled over likely bacteria presence. The Straits Times. https://www.straitstimes.com/singapore/three-types-of-goat-cheese-products-recalled-over-likely-bacteria-presence. Accessed November 21, 2024.
- Moniuszko S. Why so many listeria recalls lately? A doctor explains what to know and symptoms to look for. CBS News. https://www.cbsnews.com/news/listeria-recall-symptoms-what-to-know/. Accessed November 21, 2024.
- Get the Facts about Listeria! U.S. Food and Drug Administration. https://www.fda.gov/animal-veterinary/animal-health-literacy/get-facts-about-listeria.
- How Listeria Spread: Deli Foods and Prepared Meats https://www.cdc.gov/listeria/causes/deli-ready-to-eat-foods.html. Accessed November 21, 2024.
- Listeriosis. ID Specialists. https://idspecialists.sg/infections-treatments/listeriosis/. Accessed November 21, 2024.
- Listeria in Food. Singapore Food Agency. https://www.sfa.gov.sg/food-safety-tips/food-risk-concerns/risk-at-a-glance/listeria-in-food. Accessed November 21, 2024.