Listeriosis: what you need to know
According to a recent statement from Health Minister Dr Aaron Motsoaledi, an outbreak of food-borne listeria bacteria had claimed a number of lives and infected hundreds more in South Africa. For those concerned about this relatively unknown disease we have provided some information to assist in making good food choices.
According to the National Institute for Communicable Diseases (NICD), “Listeriosis is a serious bacterial disease caused by the bacterium, Listeria monocytogenes. The bacterium is widely distributed in nature and can be found in soil, water and contaminated food.”
While there are high risk groups such as newborns, the elderly, immunocompromised individuals, pregnant women and their unborn babies; as well as those with underlying conditions such as HIV, diabetes, cancer, chronic liver or kidney disease, the truth is anyone can contract Listeriosis.
According to the NICD, “Listeriosis is usually spread through the ingestion of contaminated food products most frequently with raw or unpasteurised milk and soft cheeses, but also vegetables, processed foods, ready-to-eat meats and smoked fish products.” Listeria can survive in normal temperatures associated with refrigeration. The Listeria bacterium can also be transmitted from a pregnant woman to her unborn baby during pregnancy or at the time of birth.
While some people (up to 10%) may appear asymptomatic, the incubation period for Listeriosis varies between 3 – 70 days. Symptoms are usually mild and may include fever, muscle pain, 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. The NICD states that pregnant women may present with mild flu-like illness associated with headache, fever and muscle pain. However, infections during pregnancy can lead to premature births, infection of the newborn with permanent disability, and miscarriage or stillbirth.
Gastro-enteritis due to Listeria usually does not require treatment. Meningitis or septicaemia due to Listeria can be life threatening and should be treated with intravenous antibiotics.
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 4oC; and freezer temperatures below -18oC.
According to the NICD there is no vaccine or pre-exposure prophylaxis for preventing infection. The main preventive measure is to always ensure that good basic hygiene is followed. This includes:
- Using only pasteurised 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.
Source: National Institute for Communicable Diseases