The chat in the corridor that raised the flag on listeriosis
Paediatrician says a 'serendipitous' meeting with a colleague led to the discovery of the outbreak
As lovers of polony and other processed meat faced a sudden change in dietary habits on Sunday, it is worth remembering that a chance conversation led to the first suggestion that there was a listeriosis outbreak.
The conversation took place between doctors at Chris Hani Baragwanath Hospital in 2017 and led to the alarm being raised about the listeriosis outbreak.
South Africa is facing the world's largest documented outbreak of listeriosis, with just under 1,000 cases. Since January last year 180 patients are known to have died.
On Sunday, Health Minister Aaron Motsoaledi announced that the epidemic could be traced to polony and other products from an Enterprise Foods factory in Polokwane‚ Limpopo.
More than 16 environmental samples from the factory tested positive for the listeriosis monocytogenes strain ST 6.The disease has killed one in three newborns who contract it from their mothers. This higher percentage is because newborns’ immune systems are believed not to be as strongly developed to fight the disease as those of adults.
Patterns in the data
South Africa is indebted to the enquiring mind of paediatrician and Wits lecturer Dr David Moore, who works in the hospital's mother and child HIV clinic.
It was in the middle of 2017, as he walked down the corridor to his office, that he stopped to chat to a colleague who treats premature babies in the hospital's neonatal ICU, and who told Moore about seven cases of listeriosis in newborns that had occurred in the first half of 2017.Being someone who “enjoys the numbers” and sees patterns in data, this made Moore think.He says listeriosis is so rare that when a case arises, doctors are “excited” by the chance to look the bacteria that behaves “unusually”. Moore guesses that at Baragwanath Hospital they only have one case a year in a newborn.
Moore was intrigued when he realised the numbers were unusually high, and raised the alarm with Dr Kerrigan McCarthy, a pathologist and head of the outbreak responses section at the National Institute for Communicable Diseases (NICD).
“It was a serendipitous meeting,” says Moore of the chat with his colleague, adding that sometimes it takes a doctor outside of the situation to see a pattern.
“Doctors working long hours with huge patient loads don’t always notice the pattern. They are inundated with patients.”The doctors “at the coalface” work at least 12 hours a day in what Moore describes as the busiest neonatal ICU in the southern hemisphere.
“Listeria doesn’t happen every week. The cases were intermittent so it wasn’t immediately obvious there was a problem or easy to notice,” Moore explains.
Nevashan Govender, the NICD’s operations manager, said the institute also received a call from a pathologist working with a huge number of test results at Tshwane’s Steve Biko Hospital, who thought there may be more cases of listeria than usual.
He says it takes a very special mind to see the pattern in huge amounts of data.
The NICD contacted private laboratories testing medical aid patients and reviewed the state laboratory’s hospital results, and realised there was an outbreak of the food-borne disease.
By December 2017 the law was changed so that listeriosis became a notifiable disease, which means that every listeriosis case and patient must be reported to the NICD.
In its hunt for the source of the listeriosis outbreak, the NICD tested about 1,500 food samples for the bacteria. More than 100 patients who had the disease were interviewed by epidemiologists who use questionnaires to probe their food history.
People at risk of listeriosis, including pregnant mothers and those with a weakened immune system, are urged by the NICD not to eat processed meats, and to heat ready-to-eat meats above 70 degrees celsius before eating.
Soft cheeses should also be avoided by pregnant women.
Moore, who is studying towards a PhD, jokes that he missed his “true calling” in epidemiology.Chasing down a strain
Staff at Chris Hani Baragwanath Hospital have been integral in fighting the outbreak.
In January 9, a paediatrician at the hospital reported five cases of food-borne disease after five children from the same creche presented with suspected food poisoning.
By January 29, Enterprise polony and Rainbow Chicken polony taken from the creche on the same day had tested positive for listeria monocytogenes strain ST6.
This strain has caused about 91% of cases in the country.
Environmental health practitioners, accompanied by World Health Organisation technical experts and members of the departments of agriculture, forestry and fisheries and health, then took more than 300 samples at the Enterprise Polokwane factory on February 2.
Of these, 16 tested positive for listeria monocytogenes strain ST6.But at least 100 samples tested positive for listeria, showing a factory that was not following adequate food safety procedures, according to Dr Juno Thomas of the National Institute for Communicable Diseases.
All foods made in that factory will have to be recalled and removed from consumers’ shelves, said the National Consumer Commission.
Thomas said that even though Rainbow Food’s chicken polony factory in Sasolburg tested positive for a different strain of listeria, there were some patients who also got sick from this strain. This is why Rainbow Chicken polony is being recalled.
Additionally, more than one Enterprise factory is implicated. Listeria bacteria was found in an Enterprise processed meat factory in Germiston on the East Rand and results on the type of listeria strain are outstanding.
National Consumer Commission deputy commissioner Thenzi Mabuza said Rainbow Chicken and Tiger Brands, which owns Enterprise, would have to come up with a plan to recall all products made in these factories.
The must present this plan on Monday morning.
The commission is investigating whether the companies withheld information about the listeria outbreak.