At the National Institute for Communicable Diseases (NICD) scientists are picking apart a monster that claimed the lives of 212 people. That monster is sequence type 6 (ST6) listeriosis, and now that the outbreak is over scientists are trying to understand what made this bacteria so deadly
Just this week they published the genome of the ST6 listeriosis responsible for the deaths in the American Society for Microbiology journal.
“There is a lot of work going on, but the reason this was expedited for publishing is so we could share the sequences with the scientific fraternity worldwide,” said Dr Juno Thomas, head of the Centre for Enteric Diseases at the NICD.
What genome revealed was that the ST6 listeriosis recovered from patients was a unique variant of the disease.
With the genome available, countries will be more able to quickly identify the strain and this will give them a clue to the origin of the disease.
The release of the genome comes as several countries across Europe are battling their own listeriosis outbreaks. The suspected source is frozen sweetcorn.
But the DNA of the South African strain of ST6 is likely to reveal more about this killer, as researchers slowly unravel its secrets.
Somewhere along the way the ST6 variant mutated, turning the bacteria deadly.
“What we want to do is see if it has genes associated with resistance to antibiotics, and disinfectants,” said Thomas. “We want to know how it persisted in the environment for so long.”
The outbreak that plagued the country is over and in the past couple of weeks there has been a sharp decline in the number of cases of the diseases.
This occurred after health authorities identified the source of the outbreak as Enterprise Food’s Polokwane production facility.
On March 4 a recall of products, including polony and other ready-to-eat processed meats, was initiated.
Now, according to Thomas, the number of listeriosis cases are down to pre-outbreak levels, with about five reported incidents a week.
Between January 2017 and June 20 2018 there were 1053 laboratory-confirmed cases of listeriosis.
Recently measures have also been put in place to prevent a similar outbreak from recurring.
On June 25 a strategy for listeriosis screening was introduced. It will involve district environmental health practitioners examining 190 food processing facilities across the country.
An emergency response plan is also being developed.
“The aim of the plan is to control and end the current listeriosis outbreak and to strengthen systems to facilitate prevention and early detection of outbreaks,” reads the latest listeriosis outbreak situation report.
However, hospitals are likely to continue to see listeriosis cases in the near future. This is because the incubation period for the disease is up to 70 days.
Also these products have long shelf lives, and there is still the possibility of cross contamination in shops or even in homes.
With the inner workings of the bacteria laid bare, the hope is that enough will be learnt so that it doesn’t make a return.