Saturday 31 March 2018

Listeria outbreak kills at least 189 in South Africa.

A total of 982 people have been infected with Listeria, with 189 known to have died, in an outbreak in South Africa, according to the National Institute for Communicable Diseases. The outbreak was first detected in January 2018 when children attending a daycare centre at a Johannesburg hospital began to fall ill with the sickness. This prompted an investigation which found the Bacterium in sandwich meat in a fridge at the centre, then at the plant which produced that meat, an Enterprise Foods operated facility in Polokwane. Since this time instances of Listeria (which has an incubation period of up to two months) across South Africa have been linked to the plant, and there is concern that other countries may have been effected, as meat is exported across Southern Africa from the site, though to date only a single case outside South Africa (in Namibia) has been associated with the outbreak. The incident is currently the largest Listeria outbreak ever recorded, according to the World Health Organisation, and it is feared there may have been many more unreported cases, as Listeria only became a notifiable disease (a disease that requires doctors to report cases to the authorities) in South Africa in December 2018.

Processed meat products from the Enterprise Foods plant in Polokwane being removed from shop shelves in South Africa following a product recall. Siphiwe Sibeko/Reuters.

Listeria monocytogenes is a facultative anaerobic Bacterium (Bacterium that does not need oxygen to survive, but which is not poisoned by it either) that is one of the most common causes of food-poisoning in Humans, causing an estimated 1600 infections and 260 fatalities in the US each year. It is a form of Firmicutes, tough cell-walled Bacteria that produce endospores capable of surviving desiccation and other extreme conditions, making the Bacteria very hard to eradicate.

Electron micrograph of a flagellated Listeria monocytogenes Bacterium, Magnified 41 250 times. Elizabeth White/Centers for Disease Control and Prevention/Wikipedia.

Listeria monocytogenes is particularly associated with unpasteurised dairy products (such as raw milk cheeses), as it is primarily an infection of Ruminant Mammals. It can cause meningitis-type infections in Humans, and is particularly dangerous to the very old, very young and those with compromised immune systems. However it can also thrive in Human gastrointestinal tracts without harming the host (it is estimated that about 10% of people are infected) raising the possibility of direst Human-to-Human transmission.

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