Guides

Listeria, Salmonella and E. coli: the basics

Three bacteria account for many of the outbreaks in this reference. They differ in how quickly symptoms appear, who is most at risk and which foods are most often involved.

• Listeria monocytogenes causes listeriosis. WHO says that unlike many foodborne bacteria it can survive and multiply at refrigerator temperatures.¹
• WHO says the invasive form of listeriosis typically appears one to two weeks after exposure but can take from a few days to 90 days, and has a death rate of 20 to 30 percent.¹
• WHO and EFSA both list pregnant women, older people and people with weakened immune systems among those most at risk of listeriosis, and EFSA also lists newborns.^1,4
• WHO says Salmonella symptoms appear 6 to 72 hours after ingestion, usually 12 to 36 hours, and the illness typically lasts 2 to 7 days. Eggs, meat, poultry and milk are the main sources.²
• Shiga toxin-producing E. coli (STEC) symptoms typically appear 3 to 8 days after exposure. WHO says up to 10 percent of patients may develop haemolytic uraemic syndrome, which can cause acute kidney failure.³
• WHO lists undercooked ground meat, raw milk and raw produce such as sprouts, spinach and lettuce among the foods linked to STEC outbreaks, and says the bacteria are destroyed when all parts of food reach 70 degrees Celsius.³
• EFSA says heating food above 65 degrees Celsius kills Listeria, but food can be contaminated again after production, for example between cooking and packaging.⁴

Sources

1. World Health Organization, Listeriosis fact sheet (20 February 2018)
2. World Health Organization, Salmonella (non-typhoidal) fact sheet (20 February 2018)
3. World Health Organization, E. coli fact sheet (7 February 2018)
4. European Food Safety Authority, Listeria (topic page) (11 February 2026)