Listeriosis is food poisoning resulting from eating foods contaminated with Listeria, a bacterium found in contaminated soil, water, vegetation, certain animals like poultry and cattle, and milk. Listeriosis is a bacterial infection most commonly caused by Listeria monocytogenes (L. monocytogenes) bacterium, although L. ivanovii and L. grayi have been reported in certain cases.
In pregnant women, the infection can result in miscarriage, premature delivery, serious infection of the newborn, or even stillbirth. Babies can be born with listeriosis if their mothers eat contaminated food during pregnancy.
Who is at Risk?
There are two main types of listeriosis, namely; a non-invasive form and an invasive form.
Non-invasive listeriosis is a mild form of the disease affecting mainly otherwise healthy people. You can become infected with Listeria and make a full recovery after about a week as a previously healthy adult or child, and most times, you rarely become seriously ill.
Invasive listeriosis is a more severe form of the disease which causes severe illness, including severe sepsis, meningitis, or encephalitis, sometimes resulting in lifelong harm and even death, affecting at-risk individuals. These include:
People with compromised immune systems
Organ transplant patients
People with HIV/Aids, autoimmune diseases, cancer, liver disease, alcoholism or diabetes
The age groups most affected are neonates (babies under 28 days old) and people between 15 and 49 years of age.
What Causes Listeriosis?
Listeria is found in soil and water.
Vegetables can become contaminated from the soil or from manure (most times from the faeces of infected animal) used as fertilizer.
Animals can carry the bacteria and can contaminate meats and dairy products.
Processed foods, such as soft cheeses and cold cuts, can be contaminated after processing.
Unpasteurized (raw) milk or foods made from unpasteurized milk can be contaminated.
Listeria, unlike many other germs, grows in cold temperatures, which makes your fridge the perfect breeding ground.
What are the Symptoms?
See a doctor immediately if you may have consumed contaminated food and experience the following flu-like symptoms:
If infection spreads to the nervous system, symptoms such as the list below can occur:
Loss of balance
But infected pregnant women may experience only a mild, flu-like illness.
How is Listeria Infection Diagnosed?
Listeriosis is diagnosed based on a medical history and physical exam. Your doctor will ask you questions about your symptoms, foods you have recently eaten, and your work and home environments. A blood test or spinal fluid test may be done to confirm the diagnosis.
How is it Treated?
Treatment is usually symptomatic depending on the severity of infection. Milder cases can be treated at home by bed rest and drinking clear fluids. A healthy person who is not pregnant typically does not need treatment.
However, a severe infection may require prolonged administration of antibiotics, primarily ampicillin and gentamicin, to which the organism is usually susceptible.
If you are pregnant and get listeriosis, antibiotics can often prevent infection of the foetus or newborn. Babies who have listeriosis receive the same antibiotics as adults.
If you suspect listeriosis, see your doctor.
How Can Listeriosis Be Prevented?
You can prevent listeriosis by practicing safe food handling.
Always practice good hygiene in the kitchen. Wash your hands regularly, and clean cutting boards, cutlery and crockery properly, especially after handling uncooked foods.
Thoroughly cook raw food from animal sources, such as beef, pork, fish, or poultry. If you’re unsure, rather overcook than undercook. Foods need to be cooked or heated to at least 70ºC to prevent infection.
Rinse raw produce, such as fruits and vegetables, thoroughly under running tap water before eating, cutting, or cooking. Even if the produce will be peeled, it should still be washed first.
Keep uncooked meats separate from vegetables and from cooked foods and ready-to-eat foods.
Avoid unpasteurized (raw) milk or foods made from unpasteurized milk.
Consume perishable and ready-to-eat foods as soon as possible.
Clean up all spills in your refrigerator right away, especially juices from hot dog and lunchmeat packages, raw meat, and raw poultry.
Recommendations for persons at high risk, such as pregnant women and persons with weakened immune systems, in addition to the recommendations listed above:
Do not eat hot dogs, luncheon meats, or deli meats, unless they are reheated until steaming hot.
Avoid getting fluid from hot dog packages on other foods, utensils, and food preparation surfaces, and wash hands after handling hot dogs, luncheon meats, and deli meats.
Do not eat soft cheeses unless the label states they are made from pasteurized milk. Common cheeses typically made with unpasteurized milk-such as feta, Brie, Camembert, blue-veined cheeses, and Mexican-style cheeses such as "queso blanco fresco"-can cause listeriosis. You can have hard cheeses and semisoft cheeses such as mozzarella along with pasteurized processed cheese slices and spreads, cream cheese, and cottage cheese.
Do not eat refrigerated pâté or meat spreads. But you can eat these foods if they are canned.
Do not eat refrigerated smoked seafood unless it is an ingredient in a cooked dish such as a casserole. Examples of refrigerated smoked seafood include salmon, trout, whitefish, cod, tuna, and mackerel. You may eat canned fish such as salmon and tuna or shelf-stable smoked seafood.
Do not drink raw (unpasteurized) milk or eat foods that contain unpasteurized milk.
Avoid eating salads made in a store, such as ham, chicken, egg, tuna, or seafood salads.
Prognosis of Listeriosis
The prognosis for individuals with listeriosis depends on several factors. Though most cases carry an excellent prognosis, those patients with underlying risk factors and severe disease are at risk for significant morbidity and mortality.