It hides in your fridge, lurking in popular foods, and it has killed up to 61 people already and it is possible the number could grow as more results are collated.
It is listeria monocytogenes, a particularly vicious bacterium which some experts are calling the worst documented listeriosis outbreak in global history.
“South Africa has a massive problem on its hands – this is one of the largest single outbreaks of listeria recorded, and the fact that the department of health (DoH) declared listeriosis as a notifiable disease on December 15, indicates how seriously they take this situation,” said Bridget Day, a food safety expert at Food Focus.
“The DoH states that the evidence in this outbreak points towards food as the vector in the transmission of the pathogen – and since 91% of the cases are presenting with the same strain of listeria (ST 6), it’s highly likely that there is one major food source which is at the heart of the outbreak.”
Yesterday in Pretoria, Minister of Health Dr Aaron Motsoaledi said 727 laboratory-confirmed cases had occurred in the country since January 2017.
“This means that since the last press conference of December 5, 2017, a total of 170 extra cases emerged. Of these 170, a total of 51 had already occurred before December 5, only that we are discovering them now as the search continues; hence they were captured retrospectively,” he said.
This made for 119 new cases in a month.
According to the National Institute for Communicable Diseases’ (NICD) January 4 update, these numbers could change “due to recent challenges with [National Health Laboratory Service] laboratory information system data [since epidemiological week 47] and a possible lag in reporting as a result of the public holidays” and the total results “are likely to change on a daily basis and trends must be interpreted with caution until it has been confirmed that all cases have been captured”.
Dr Patrick Ngassa of Public Health Consultancy said the problem – finding the source – was all the more challenging when only 18.43% of patients had been traced so far.
“The sooner DoH and NICD trace patients the better, because they will be able to reduce the number of potential premises to test as a result of identifying common points during patient interviews,” Ngassa said.
“My concern is that we could have an underestimation of the actual number of deaths since they have only traced 134 patients, of which 45.5% passed away. If you apply that 45.5% death rate to 727 patients you have around 300 patients dead,” Ngassa noted.
Dr Lucia Anelich‚ food microbiologist and director of Anelich Consulting which offers food safety expertise, said foodborne disease outbreaks tended to follow a specific pattern – growing in numbers, peaking at a certain point and then declining in numbers over time.
“This is due to the contaminated product being sold and consumed over time until the product has all been consumed and that batch is no longer available in the market. However, if a processing facility has listeria in the environment of the facility, there may be a continuous contamination of freshly processed product over time,” Anelich said.
“This latter scenario may result in a continued number of cases. This is why it’s important to link the actual outbreak strain to a processing facility, so that adequate control measures can be taken to stop the outbreak and prevent future ones arising from that particular facility.”
Listeriosis cases as of January 8:
- Gauteng 61% (442/727)
- Western Cape 13% (92/727)
- KwaZulu-Natal 7% (51/727)
- 65% of cases occurred in the public sector
- 35% occurred in the private sector