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Listeriosis and food safety: an insight into the current outbreak in South Africa. The Agricultural Research Council (ARC). Contents. Classification of Listeria monocytogenes Listeria monocytogenes and food safety Implications of and possible sources of listeriosis
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Listeriosis and food safety: an insight into the current outbreak in South Africa The Agricultural Research Council (ARC)
Contents • Classification of Listeria monocytogenes • Listeria monocytogenesand food safety • Implications of and possible sources of listeriosis • Current status of the Listeriosis outbreak in South Africa • ARC involvement with Listeriosis • ARC Listeriosis study • Pervasiveness of listeria and other pathogens • Poor Food Safety Practices • Food Regulation and surveillance systems • Food handling tips to minimize chances of contamination
What is Listeria? • The genus Listeria belongs to the class Bacilli and the order Bacillales, which also includes Bacillus and Staphylococcus • The genus consists of at least 17 recognized species that includes Listeria monocytogenes • Listeria monocytogenes is the species of pathogenic bacteria that causes the infection listeriosis • It can grow and reproduce inside the host's cells and is one of the most virulent foodborne pathogens • Listeriamonocytogenes organisms are short, gram-positive, rod-shaped, non-spore-forming, facultative anaerobic, non-branching, etc bacteria. • Listeria species can grow in a temperature range of 0-45°C and within a pH range of 5.9-9.6. • These growth conditions contribute to its versatility to propagate in many food products. • Although rare, the mortality rate of listeriosis is 30% worldwide and hospitalization rate of >95%.
Listeria monocytogenes and food safety • L. monocytogenes is a foodborne pathogen causing listeriosis in animals and humans- 20 to 30% of food borne listeriosis infections in high-risk individuals may be fatal • Listeriosis is characterized by fever, muscle aches, and nausea. If infection spreads to the nervous system, symptoms such as headache, stiff neck, confusion, loss of balance even death. • Vulnerable groups are pregnant women, elderly, infants and individuals who are immunocompromised. • In pregnant women, the infection can result in miscarriage, premature delivery and serious infection of the newborn or even stillbirth. • Although rare, the mortality rate of listeriosis is 30% worldwide and hospitalization rate of >95%.
Possible sources of listeriosis • L. monocytogenes is an environmental pathogen that is found in soil, water, sewage, and decaying vegetation. • Listeriosis is caused by eating foods contaminated with the Listeria monocytogenes. • Listeriosis infections are linked to diverse foods including fresh produce, dairy and meat products. • The vast majority of human listeriosis cases are commonly linked to ready to eat (RTE) food products because they are not heat treated before eating.
Implications of listeriosis • Listeriosis ranks amongst the deadliest foodborne diseases worldwide due to fatality rates of 25-30% and hospitalization rate of >95%. • Socio-economic implications due to food recalls, litigations, hospitalization and death amount to a huge burden to the nation. • This is evident in the current outbreak in the country which cost Tiger brand an estimated R 350 million in food recalls. • Economic losses due to South African RTE products being banned for export market.
Current status of Listeriosis outbreak in South Africa • As of 04 March 2018, an outbreak of human listeriosis recently reported by National Institute for Communicable Diseases (NICD) had identified a total of 984 laboratory-confirmed human cases from all provinces across the country which resulted in 180 deaths. • The source has been linked to RTE processed meat products (polony, viennas/sausages and other cold meats). • The conclusion was made by the Department of Health that the source of the outbreak was the Enterprise Food production facility in Polokwane, (Germiston?) and RCL Wolwehoek, Sasolburg.
ARC involvement with Listeriosis • At the time of the recent outbreak ARC assisted by sending 77 isolates to NICD for whole genome sequencing. • ARC provided metadata to NICD/DoH for the total number of samples tested. • At the time of the outbreak ARC was the only institution that had metadata and isolates of Listeria monocytogenes. • Sequence data from our isolates were compared to those from field samples in order to establish a relationship and assist in tracing the source of the current outbreak. • The isolates and metadata would therefore help the NICD make accurate diagnosis of the L. monocytogenesstrain or strains responsible for the listeriosis outbreak • Without the data and isolates from the ARC it is most likely we would still be trying to resolve the issue to this day.
ARC Listeriosis Study • In 2014-2016 ARC conducted a research project for profiling, quantification and characterization of bacterial foodborne pathogens isolated from local and imported meat and meat products in South Africa. • A total of 2 017 meat and meat product samples were collected across 9 provinces and three ports of entry (Durban, Cape Town and Port Elizabeth). • Samples were tested for Listeria species (including L. monocytogenes) among other foodborne pathogens. • Total of 582 samples tested positive for Listeria spp., (296 were L. monocytogenes). • The overall occurrence of L. monocytogenes was 14.7% (296/2017); domestic market (15.0%; 264/1758) and ports of entries (12.4%; 32/259).
What does this mean? • What we saw with the most recent outbreak of listeriosisis the tip of the iceberg- L. monocytogenesand other pathogens are always a threat in the environments that our foods go through • Ready-to-eat foods were found to be the main vehicle for transmission of the Listeria through contamination somewhere in the food chain • Because of improper handling or processing or storage ready to eat and other foodstuffs can be vehicles for transmitting other food-borne pathogens like Salmonella, E. coli and even clostridium botulinum • We know that many people in rural areas, small towns and townships consume meat and milk that have not been subjected to any method of destroying pathogenic microorganisms • We also know that meat and milk because they are good media for the growth of microorganisms are on paper some of, if not, the most regulated foodstuffs but many municipalities do not enforce the regulations and as a result unscrupulous operators get away with selling foodstuff that are not suitable for consumption
Poor Food Safety Practices • We also know that at taxi or bus ranks in townships and small rural towns people are able to buy all kinds of foodstuffs that range from fruit and vege to livestock and live chickens. Often these are next to one another, which promotes easy contamination • There are millions of livestock that are slaughtered annually at our households for ceremonies, rituals and funerals • We consume fresh milk form our cows, goats, sheep and other animals that we keep around the house • These practices present a certain degree of exposure to mircroorganisms that can cause us harm • What we are sold especially in products like burgers, pies and processed meats is not always what we expect or is claimed to be by the manufacturers
Food Regulation • Departments of Health, Agriculture, Forestry and Fisheries, the Dept of Health, Dept of Trade and Industry and municipalities are involved with food regulation but little or no coordinating mechanism • Many unscrupulous operators cut corners with impunity • We need to improve our regulatory and monitoring efforts if we want promote food safety in the country • We need to have properly coordinated surveillance systems • We need to have severe penalties for those operators who are not compliant • Should we have food control agency that will be tasked with all these activities that are currently in the hands of various departments and municipalities?
The Case for Surveillance • Focused training and capacity building-training and human capital development are critical for continuous and effective diagnostic and surveillance programmes • Strengthen national capacity- regulatory departments and industry control programs should be strengthened. • Surveillance by entities like DAFF should not be limited to ports of entry alone. • The entire value chain in the food industry and agriculture sector be focus of the surveillance programs.
Targeted Surveillance activities • Ready-to-eat foods are the main vehicle for transmission of Listeria through contamination somewhere in the food chain during the last outbreak • Meat, poultry and dairy products have been most frequently implicated in the past in this country and elsewhere, • But other foods including produce may also have been vehicles of transmission. • Outbreaks may also be linked to errors in food processing plants, such as contaminated machines, environment, water, followed by opportunities for growth of the pathogen. • Fresh produce such as vegetables, fruits are also implicated as source of outbreaks.
Surveillance proposal/laboratory diagnosis • Primary production • Farm and feedlot levels • Sample type: feed, faeces, milk, water, fruits and vegetables • Secondary • Abattoir, food processing plants, fruits markets • Sample type: meat, meat products, dairy products, environmental swabs, fruits and vegs • Tertiary • Wholesale, butcheries, retail outlets • Sample type: meat, meat products, dairy products, environmental swabs, fruits and vegs • Test methods proposed: • Detection and enumeration using culture-based and DNA-based methods
Hygiene practices at slaughter and consumption facilities • Heighten awareness about food poisoning • Develop awareness materials on safe and hygienic handling of food, animals and animal products. Food storage and preparation. • Sensitise the public that consumption of raw and uncooked food items is a risk to health. • Milk should be boiled before consumption. • Avoid slaughtering of animals in unsafe and unclean areas • Promote use of mobile abattoirs that are manned by a meat inspector for slaughtering for ceremonies and rituals
Food contamination prevention tips at household level • Instil practice of safe handling and preparation of food. • Keep different meat items from the shop in separate bags. • Always cook meat thoroughly to kill bacteria, and maintain careful hygienic practices in the kitchen. • Always wash your hands before and after handling fresh produce. • Wash fresh produce thoroughly before peeling, cutting, and cooking. • Store your food at below 0 degrees Celsius, and clean up any spills in the fridge immediately.
