WHO on Wednesday warned Nigeria and 15 other African countries of a listeriosis outbreak that started in South Africa in 2017, confirming that they are preparing to deal with an eminent outbreak. Haven’t heard about listeriosis? Wondering what it is? Here, we tell you exactly what it is and how to best protect yourself against it.
The other African countries listed as being at risk are Angola, Botswana, the Democratic Republic of Congo, Ghana, Lesotho, Madagascar, Malawi, Mauritius, Mozambique, Namibia, Swaziland, Tanzania, Uganda, Zambia and Zimbabwe.
What is listeriosis?
Listeriosis is a series of diseases caused by the bacteria L. monocytogenes, outbreaks of which occur in all countries. There are two main types of listeriosis: a non-invasive form and an invasive form.
Noninvasive listeriosis (febrile listerial gastroenteritis) is a mild form of the disease affecting mainly otherwise healthy people. Symptoms include diarrhoea, fever, headache and myalgia (muscle pain). The incubation period is short (a few days). Outbreaks of this disease have generally involved the ingestion of foods containing high doses of L. monocytogenes.
Invasive listeriosis is a more severe form of the disease and affects certain high risk groups of the population. These include pregnant women, patients undergoing treatment for cancer, AIDS and organ transplants, elderly people and infants. This form of disease is characterized by severe symptoms and a high mortality rate (20%–30%). The symptoms include fever, myalgia (muscle pain), septicemia, meningitis. The incubation period is usually one to two weeks but can vary between a few days and up to 90 days.
The initial diagnosis of listeriosis is made based on clinical symptoms and detection of the bacteria in a smear from blood, cerebrospinal fluid (CSF), meconium of newborns (or the fetus in abortion cases), as well as from faeces, vomitus, foods or animal feed. Various detection methods, including polymerase chain reaction (PCR), are available for diagnosis of listeriosis in humans. During pregnancy, blood and placenta cultures are the most reliable ways to discover if symptoms are due to listeriosis.
Pregnant women are about 20 times more likely to contract listeriosis than other healthy adults. It can result in miscarriage or stillbirth. Newborn may also have low birth weight, septicaemia and meningitis. People with HIV/AIDS are at least 300 times more likely to get ill than those with a normally functioning immune system.
Due to the long incubation period, it is challenging to identify the food which was the actual source of the infection.
What are the symptoms?
The symptoms of listeriosis include fever, muscle aches, and sometimes nausea or diarrhea. If infection spreads to the nervous system, symptoms such as headache, stiff neck, confusion, loss of balance, or convulsions can occur. But infected pregnant women may experience only a mild, flu-like illness.
How is listeriosis 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?
An otherwise healthy person who is not pregnant typically does not need treatment. Symptoms will usually go away within a few weeks.
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, although a combination of antibiotics is often used until your doctor is certain the cause is listeriosis.
How can you prevent listeriosis?
You can prevent listeriosis by practicing safe food handling (adapted from the U.S. Centers for Disease Control and Prevention).
- Shop safely. Bag raw meat, poultry, or fish separately from other food items. Drive home immediately after finishing your shopping so that you can store all foods properly.
- Prepare foods safely. Wash your hands before and after handling food. Also wash them after using the bathroom or changing diapers. Wash fresh fruits and vegetables by rinsing them well with running water. If possible, use two cutting boards-one for fresh produce and the other for raw meat, poultry, and seafood. You can also wash your knives and cutting boards in the dishwasher to disinfect them.
- Store foods safely. Cook, refrigerate, or freeze meat, poultry, eggs, fish, and ready-to-eat foods within 2 hours. Make sure your refrigerator is set at 40°F (4°C) or colder. But listeria can grow in the refrigerator, so clean up any spills in your refrigerator, especially juices from hot dogs, raw meat, or poultry.
- Cook foods safely. Use a clean meat thermometer to determine whether foods are cooked to a safe temperature. Reheat leftovers to at least 165°F (74°C). Do not eat undercooked hamburger, and be aware of the risk of food poisoning from raw fish (including sushi), clams, and oysters.
- Serve foods safely. Keep cooked hot foods hot [140°F (60°C) or above] and cold foods cold [40°F (4°C) or below].
- Follow labels on food packaging. Food packaging labels provide information about when to use the food and how to store it. Reading food labels and following safety instructions will reduce your chance of becoming ill with food poisoning.
- When in doubt, throw it out. If you are not sure whether a food is safe, don’t eat it. Reheating food that is contaminated will not make it safe. Don’t taste suspicious food. It may smell and look fine but still may not be safe to eat.
If you are pregnant:
- Do not eat hot dogs, luncheon meats, or deli meats, unless they are reheated until steaming hot.
- Do not eat soft cheeses unless the label states they are made from pasteurised milk. Common cheeses typically made with unpasteurised 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 semi-soft cheeses such as mozzarella along with pasteurised 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 (unpasteurised) milk or eat foods that contain unpasteurised milk.
- Avoid eating salads made in a store, such as ham, chicken, egg, tuna, or seafood salads.