Listeriosis (Human)
Primary reference(s)
WHO, 2018. Listeriosis. World Health Organization (WHO). Accessed 19 November 2019.
Additional scientific description
There are two main types of listeriosis: a non-invasive form and an invasive form.
Non-invasive 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). Outbreaks have generally involved the ingestion of foods containing high doses of Listeria monocytogenes (WHO, 2018).
Invasive listeriosis is a more severe form of the disease and affects certain high-risk groups of the population, including pregnant women, immunocompromised individuals (such as those with HIV/AIDS, leukaemia, cancer, kidney transplant and steroid therapy), elderly people and infants. This form of disease is characterised by fever, myalgia, septicaemia and meningitis, and other severe symptoms, including abortion in pregnant women. It is associated with a high mortality rate (20%–30%). The incubation period of listeriosis is usually one to two weeks but can vary from a few days up to 90 days (WHO, 2018).
Unlike many other common foodborne diseases causing bacteria, L. monocytogenes can survive and multiply at the low temperatures usually found in refrigerators. In past outbreaks, foods involved have included ready-to-eat meat products, such as frankfurters, meat spread (paté), smoked salmon and fermented raw meat sausages, as well as dairy products (including soft cheeses, unpasteurised milk and ice cream) and prepared salads (including coleslaw and bean sprouts) as well as fresh vegetables and fruit. Eating contaminated food with high numbers of L. monocytogenes is the main route of infection (WHO, 2018).
Infection can also be transmitted between humans, notably from pregnant women to unborn babies. Pregnant women are about 20 times more likely to contract listeriosis than other healthy adults. It can result in miscarriage or stillbirth. Newborn babies 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 (WHO, 2018).
Owing to the long incubation period, it is challenging to identify the food which was the actual source of the infection (WHO, 2018).
Metrics and numeric limits
Listeriosis is a relatively rare disease with 0.1 to 10 cases per 1 million people per year depending on the countries and regions of the world. Although the number of cases of listeriosis is small, the high rate of death associated with this infection makes it a significant public health concern (WHO, 2018).
The European Centre for Disease Prevention and Control (ECDC) has published case classification for outbreak management and national epidemiological surveillance (ECDC, 2018).
Key relevant UN convention / multilateral treaty
International Health Regulations (2005), 3rd ed. (WHO, 2016).
Codex Alimentarius (FAO and WHO, no date).
Examples of drivers, outcomes and risk management
The control of Listeria monocytogenes is required at all stages in the food chain and an integrated approach is needed to prevent the multiplication of this bacteria in the final food product (WHO, 2018).
The World Health Organization (WHO) and Food and Agriculture Organization of the United Nations (FAO) have published an international quantitative risk assessment of Listeria in ready-to-eat foods. This formed the scientific basis for the Codex Alimentarius Commission Guidelines on the Application of General Principles of Food Hygiene to the Control of Listeria monocytogenes in Food (FAO, 2009).
In general, guidance on the prevention of listeriosis is similar to guidance used to help prevent other foodborne illnesses. This includes practicing safe food handling and following the WHO Five Keys to Safer Food (WHO, 2006).
References
ECDC, 2018. Commission implementing decision (EU) 2018/945 of 22 June 2018 on the communicable diseases and related special health issues to be covered by epidemiological surveillance as well as relevant case definitions. European Centre for Disease Prevention and Control (ECDC). Accessed 19 November 2019.
FAO, 2009. Guidelines on the application of general principles of food hygiene to the control of Listeria Monocytogenes in foods. Food and Agriculture Organization of the United Nations (FAO). Accessed 19 November 2019.
FAO and WHO, no date. About Codex Alimentarius. Food and Agriculture Organization of the United Nations (FAO) and World Health Organization (WHO). Accessed 19 September 2020.
WHO, 2006. Five key ways to safer food manual. World Health Organization (WHO). Accessed 19 November 2019.
WHO, 2016. International Health Regulations (2005), 3rd ed. World Health Organization (WHO). Accessed 26 September 2020.
WHO, 2018. Listeriosis. World Health Organization (WHO). Accessed 19 November 2019.