Experts uncertain over source of listeria outbreak

“A widely available common food source” distributed from the Gauteng province could be behind the recent outbreak of listeria, say experts. However, they are not sure what the culprit is.

The bacterial disease, listeriosis, which infects the blood stream and the nervous system, has led to 557 confirmed cases and 39 reported deaths. This was the highest number of reported cases in South Africa’s history, according to the National Institute for Communicable Diseases (NICD).

Typically, only about 80 cases of listeriosis were reported per year. The institute said in Gauteng, the rate of known infections increased from two per million to eight per million.

The highest incidence was recorded in the City of Johannesburg at 12 cases per million. Of the 345 cases in Gauteng, over 60% were new-born babies.

Dr Juno Thomas, a pathologist and head of the centre for enteric diseases at the NICD, said the most likely cause was a food source available to everyone – regardless of their social status.

“Because we see cases from both public and the private health sector and the fact that initially we first saw cases in Gauteng predominantly and then in the Western Cape and KZN, this indicates to us the likely burden of exposure was firstly among persons living in Gauteng. It’s more likely that the contaminated foodstuff was distributed further afield, but it originated here,” said Thomas.

Where those infected died, the usual causes were septicaemia or meningitis as a result of infection.

The most vulnerable, according to the institute, were pregnant women and people living with HIV. Of the patients where the HIV status was known, 63% of those infected were also HIV positive. Infants accounted for 37% of the cases.