Expert shares insights into outbreak trends in South Africa
The real burden of foodborne disease and outbreaks in South Africa is not clear, according to a specialist from the country’s public health institute.
Juno Thomas, from the National Institute for Communicable Diseases (NICD), said there were a lot of unknowns about food and waterborne disease in the country.
“The data we have really represents the tip of the iceberg. The true burden of disease is the great unknown. We try to improve on sources of data and completeness but it is a mammoth task and it is going to be a labor of love for many of us for years to come,” she said during a presentation at the South African Food Safety Summit, which was sponsored by Marler Clark, the publisher of Food Safety News.
“Until there is a coordinated approach to looking at the data more holistically, we will continue to have these narrow perspectives and not be able to get a true understanding of what the food safety issues are in South Africa and where we need to focus research on food borne disease.”
Lack of a complete picture
Thomas said one of the problems was very little data was available.
“The data sources we do have vary in completeness for particular pathogens. The best data, the most complete epidemiological, laboratory and molecular data, is for Salmonella Typhi and Salmonella Paratyphi A, B and C and Listeriosis. For non-typhiodal Salmonella, Shigella, Campylobacter and E. coli we rely on data from lab-based surveillance through the GERMS-SA platform at the NICD. This relies on voluntary submission of isolates from public and private sector labs. We really have no way of knowing how many cases of these organisms we are missing,” she said.
“The use of PCR and cultural-independent diagnostic tests means there won’t be isolates for those cases and they won’t be counted by us. There are no sources of aggregated national data for enteric viruses, for toxin producing bacteria, such as Staphylococcus aureus, Bacillus cereus and Clostridium perfringens, and enteric parasites. We know that just relying on the notifications that come through the system underrepresents even the recognized outbreaks that are there.”
Data and isolates from private sector labs are no longer always shared with the NICD after the 2017 to 2018 listeriosis outbreak linked to polony made by Tiger Brands and Thomas said this “unfortunate collateral damage” meant everyone was working in siloes.
Overall, 355 outbreaks were reported to NICD from 2018 to 2021 but only 146 were investigated. The majority occurred in the household followed by educational settings like schools and universities.
“2019 was a bumper year for foodborne outbreak reporting and in the first few months of 2020, preceding the hard lockdown, there were a number of outbreaks. Since the lockdown, and continuing into 2021, there have been relatively few outbreaks and months at a time were not a single outbreak was reported,” said Thomas.
“We aren’t sure whether this is due to changed health-seeking behavior during the COVID-19 pandemic or whether the non-pharmaceutical measures we implemented as part of the controls, which includes hand hygiene, restaurants not open and events being closed, are factors that resulted in a real decline in foodborne disease.”
There were a number of common themes in these outbreaks, Thomas said.
“Firstly, the most commonly identified pathogen is always non-typhiodal Salmonella and is typically associated with meat, poultry and eggs. We haven’t yet seen an outbreak where the Salmonella in patients can be directly linked to another type of food such as fruit or vegetables,” she said.
“We’ve seen an association of Salmonella outbreaks with informal and ritual slaughter of food animals, in particular goats. We’ve seen an emergence of Salmonella Newport associated with goats used in ritual slaughter but we see a range of Salmonella serovars from informal slaughter of goats and cows.”
Eating meat not fit for human consumption is another growing problem.
“This speaks to food insecurity and issues around animal health. We’ve seen an increasing number of outbreaks associated with eggs, in some cases we’ve had informal caterers that buy cracked eggs from producers at a reduced price and then use them in mass catering. We’ve also seen outbreaks in hospitals were non-irradiated eggs are used and patients are allowed to choose whether they would like their eggs soft or not, which is a major food safety issue in a healthcare facility environment,” said Thomas.
“Poor food safety practice in the home is an ever present problem. There is much to be done in terms of health education and improving basic food safety practice throughout the country. We’ve seen an increase in outbreaks associated with events like funerals and weddings. Informal caterers or members of a family that do mass catering and often there are major problems with hand hygiene, food storage and reheating. School feeding schemes are also of great concern as these types of outbreaks are second only to household outbreaks, again there are problems with basic food safety practice.”
The virtual event also had sessions on big data, cybersecurity and ransomware and food defense as well as panel discussions on food fraud and product recalls in South Africa.
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