Would you be able to list every single thing you've eaten in the past month?
That's what victims of South Africa's massive listeriosis outbreak - the biggest on record globally - are being asked to do by the National Institute for Communicable Diseases (NICD) in an attempt to pinpoint the source.
The number of confirmed listeriosis cases is now 872, and 164 of those have died - up from 107 last week. The current mortality rate is a staggering 27%.
Of those confirmed cases, 43% were babies of less than a month old – pregnant women being 20 times more likely to get listeriosis than other healthy adults.
Contracted by eating food containing the listeria pathogen, listeriosis is by far the most deadly of food-borne diseases. Given the scale of our mystery outbreak, it has led to what one delegate termed "listeria hysteria", at a listeriosis workshop hosted by the South African Association of Food Science and Technology (SAAFoST) in Johannesburg on Wednesday.
While patés, soft cheeses and guacamole have been found to be the source in listeriosis outbreaks in other countries, our outbreak is unlikely to be a "high-end luxury food item", said the NICD's Dr Juno Thomas at the workshop.