Outbreak of listeriosis in South Africa
The Minister of Health, Dr Aaron Motsoaledi, issued a media release on the current outbreak on 5 November. This followed the release of a situation report by the Centre for Enteric Diseases (CED) and Division of Public Health Surveillance and Response, Outbreak Response Unit (ORU), National Institute for Communicable Diseases (NICD)/ National Health Laboratory Service (NHLS) on 4 December 2017.
The report can be downloaded from http://www.nicd.ac.za/…/situation-report-on-listeriosis-out….
Cause of listeriosis
Listeriosis is a serious, but treatable and preventable disease caused by the bacterium, Listeria monocytogenes. The bacterium is widely distributed in nature and can be found in soil, water and vegetation. Animal products and fresh produce such as fruits and vegetables can be contaminated from these sources.
Signs and symptoms of listeriosis
• Flu-like illness with diarrhoea including fever, general body pains, vomiting and weakness
• Meningoencephalitis (infection of the brain)
People at risk of developing severe disease
These include newborns, the elderly, pregnant women, persons with weak immunity such as HIV, diabetes, cancer, chronic liver or kidney disease.
The current outbreak
Listeria monocytogenes is a disease that occurs every year. Typically, 60 – 80 cases are detected and treated annually in South Africa. However, in July 2017 doctors from neonatal units in Chris Hani Baragwanath and Steve Biko Academic hospitals alerted the NICD about the unusually high number of babies with listeriosis. This triggered a review of all cases diagnosed in both public and private hospitals.
Between 1 January 2017 and 29 November 2017, a total of 557 laboratory-confirmed listeriosis cases were reported from all provinces. Most cases were reported from Gauteng (62%) followed by Western Cape (13%) and KwaZulu-Natal (7%), a total of 82 per cent of reported cases. The remaining 18 per cent was distributed in the remaining six provinces.
The age groups that are most affected are neonates, i.e. the first 28 days of life (37%) and the age group between 15 to 49 years (33%). These two groups comprise 70 per cent of all cases.
Of the 557 laboratory confirmed cases, 34 per cent were from private health facilities and 66 per cent were from public health facilities. This indicates that the source of the outbreak is likely to be a food product that is widely distributed and consumed by people across all socio-economic groups.
Out of 557 cases, the final outcome (discharge or death) is known for 70 cases. Of these 70 cases, 36 people died.
Food safety in South Africa is managed intersectorally by the Departments of Health, Agriculture, Forestry and Fisheries, as well as Trade and Industry. Local government is responsible for municipal health services which include the enforcement of food safety legislation. The DTI looks after all aspects of fish and fishery products while DAFF manages meat safety and animal health.
There are four possible sources of listeriosis in general. These are:
• directly at origin e.g. farm
• food processing plant
• food preparation at home
For this particular outbreak, the most likely possible source is contamination food at origin, e.g. farms and agriculture, as well as food processing plants.
The source of this outbreak is currently being investigated, and all the stakeholders are cooperating with the investigation led by the NICD. Environmental Health Officers are following up diagnosed cases and are visiting their homes to sample food where available. Private food testing laboratories have been requested to provide data on listeria to date, as well as to provide isolates to the NICD. Thus far two have voluntarily submitted isolates from food samples. In addition, five food and laboratory associations have also been requested to provide information to their members that have been testing for listeria. Government Laboratory Systems are also communicating their information to the NICD.
The NICD has made information available on their website regarding Listeriosis, including frequently asked questions (FAQs), clinical management guidance, and laboratory testing methodology.
Keys to food safety from the World Health Organisation
• Keep clean. Hands must be washed before handling food and often during food preparation.
• Separate raw and cooked food.
• Cook food thoroughly. Food that does not usually need cooking before eating, needs to be thoroughly washed with clean running water. Families with no source of clean running water need to boil their water before domestic use.
• Keep food at safe temperatures. Food to be kept cold should be refrigerated and food to be served hot should be served hot.
• Use safe water and raw materials at all times. Milk products should be pasteurized, but where this is not possible, milk should be boiled prior to use.
For members of the public: NICD Emergency Operations Centre during working hours (011 386 2000)
For healthcare workers: NICD Hotline for Clinical Emergencies after hours (082 883 9920)