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Health condition · Clinically reviewed

Listeria infection, a food-borne risk that matters most in pregnancy.

Usually mild in healthy adults, but capable of serious harm in pregnancy, older age and immunosuppression - and it can grow quietly in the fridge.

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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against UKHSA, RCOG and BASHH sources you can see at the end.

  • 03

    Current for 2026

    Reflects UK notification duties, pregnancy pathways and first-line antibiotic choices.

Key facts

Listeria infection at a glance.

The essentials, in plain English - what it is, where it comes from, and who needs to take extra care.

  • What it is

    Listeriosis - a bacterial infection caused by Listeria monocytogenes, usually picked up from contaminated food.

  • Where it hides

    Unpasteurised dairy, soft cheeses, deli meats, smoked fish, pre-packed salads and refrigerated pâté - and it can grow at fridge temperatures.

  • Who it hits hardest

    Pregnant women, older adults, newborns and anyone immunocompromised - most healthy adults barely notice it.

  • Notifiable disease

    Listeriosis is notifiable in the UK - every confirmed case goes to UKHSA for surveillance and outbreak tracing.

  • First-line treatment

    IV amoxicillin or ampicillin, often with gentamicin - listeria has natural resistance to cephalosporins.

  • Pregnancy risk

    Placental tropism means it can trigger miscarriage, stillbirth, preterm labour or neonatal sepsis - specialist care is essential.

Why this guide matters

Mild for most, serious for some.

Listeria rarely troubles a healthy adult. But for a small number of people, the same exposure can be genuinely dangerous. The three points below shape everything else on this page.

  • It hides in ordinary foods

    Soft cheeses, pâté, smoked fish and pre-packed salads are everyday items - the risk is invisible unless you know to check.

  • Pregnancy changes the stakes

    Listeria crosses the placenta more readily than most bacteria, which is why pregnancy advice is so specific.

  • Speed matters once symptoms start

    Invasive disease in a high-risk patient is a specialist emergency - blood cultures and IV antibiotics start without delay.

How the diagnosis is made

From suspicion to a confirmed diagnosis.

The steps a UK clinician will normally follow when listeria is suspected - so you know what to expect and why.

  1. 01

    Assessing

    Food and exposure history

    What was eaten, when, and whether the patient is pregnant or immunosuppressed shapes everything that follows.

  2. 02

    Assessing

    Symptom and risk review

    Fever, muscle aches and flu-like illness in a high-risk group are taken seriously even when they look mild.

  3. 03

    Confirming

    Blood cultures

    The mainstay investigation for suspected invasive disease - taken before antibiotics whenever possible.

  4. 04

    Confirming

    CSF culture if meningitis suspected

    A lumbar puncture and specialist microbiology input when headache, neck stiffness or confusion point to the brain or its coverings.

  5. 05

    Confirming

    Placental and amniotic fluid culture

    In pregnancy-associated cases, samples from the placenta or amniotic fluid help confirm transmission to the baby.

  6. 06

    Coordinating

    UKHSA notification

    Confirmed cases are reported to UKHSA, who may trace the food source and investigate wider outbreaks.

  7. 07

    Coordinating

    Specialist obstetric and neonatal input

    Pregnancy cases involve joint obstetric and neonatal planning around delivery timing and newborn monitoring.

Typical timeline: blood cultures and specialist input within hours, not days, once invasive disease is suspected.

Symptoms

What listeria infection actually looks like.

From a mild stomach upset to bloodstream infection or meningitis - and the pregnancy pattern that deserves particular care.

  • Non-invasive gastroenteritis

    Diarrhoea, cramping and fever in an otherwise well adult - usually self-limiting and settles without antibiotics.

  • Bacteraemia and sepsis

    Fever, chills and feeling generally unwell as the bacteria enter the bloodstream - a specialist emergency in at-risk groups.

  • Meningitis and meningoencephalitis

    Headache, neck stiffness, confusion or seizures - more common in the elderly and immunocompromised.

  • Flu-like illness in pregnancy

    Fever, aches and tiredness in the mother, often mild, but with serious potential consequences for the pregnancy.

  • Early-onset neonatal disease

    Infection acquired in utero, present at or shortly after birth - a specialist obstetric and neonatal emergency.

  • Late-onset neonatal disease

    Meningitis appearing days to weeks after birth, thought to be acquired around delivery.

  • Immunocompromised and elderly patients

    Higher risk of invasive disease from the same food exposure that a healthy adult would shrug off.

  • Red flag - pregnancy or neurological signs

    Fever in pregnancy, or any confusion, stiff neck or severe headache, needs same-day specialist assessment.

Treatment

How listeria infection is treated in the UK.

IV amoxicillin or ampicillin first, with specialist obstetric, neonatal or neurology input where the case demands it.

  • IV amoxicillin or ampicillin

    First-line for invasive disease - listeria has intrinsic resistance to cephalosporins, so these are avoided.

  • Combined with gentamicin

    Often added for a synergistic effect in severe bacteraemia or sepsis, under specialist guidance.

  • Meningitis - prolonged course

    A longer IV antibiotic course than for bacteraemia alone, led by specialist microbiology and neurology input.

  • Pregnancy - IV antibiotics

    Started promptly alongside specialist obstetric review, with delivery timing planned around the mother and baby.

  • Neonatal team involvement

    Babies born to an infected mother, or showing signs themselves, need specialist neonatal assessment and treatment.

  • Supportive care

    Fluids, monitoring and symptom control alongside antibiotics, particularly in sepsis or meningitis.

  • Dietary prevention advice

    Avoiding high-risk foods - unpasteurised dairy, soft cheeses, pâté, pre-packed salads - and reheating food thoroughly.

  • UKHSA outbreak investigation

    Food traceability and cluster analysis when cases suggest a shared source, alongside public health teams.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP, midwife or specialist knows your history and can tell you which parts apply to you. If in doubt, get seen.

  • UK Health Security Agency (UKHSA). Listeriosis: guidance, data and surveillance.

  • Royal College of Obstetricians and Gynaecologists (RCOG). Guidance on listeriosis in pregnancy.

  • British Association for Sexual Health and HIV (BASHH). Management of invasive bacterial infection.

  • NICE. Clinical guidance on antimicrobial prescribing for invasive infection.

Red flags

When listeria infection needs urgent attention.

Most exposures pass unnoticed. These are the situations that need same-day or emergency care.

  • Fever in pregnancy

    Any unexplained fever in pregnancy, especially with a history of high-risk food, warrants urgent assessment.

  • Reduced fetal movements or contractions

    Alongside fever or flu-like illness, these need same-day obstetric review to check for pregnancy-associated infection.

  • Neck stiffness, confusion or severe headache

    Possible meningitis or meningoencephalitis - especially in older or immunocompromised patients - needs emergency care.

  • Sepsis signs

    Fast breathing, low blood pressure, mottled skin or extreme drowsiness alongside fever - call 999 or attend A&E.

  • Neonatal illness after birth

    A newborn who is floppy, feeding poorly, or has a fever or breathing difficulty needs immediate neonatal review.

  • Known unpasteurised food exposure

    In pregnancy or immunosuppression, even mild symptoms after eating a high-risk food deserve a call to a GP or midwife.

  • Seizures

    A new seizure with fever points to possible central nervous system involvement and needs emergency assessment.

  • Failure to improve on treatment

    Ongoing fever or deterioration despite antibiotics should prompt urgent specialist microbiology review.

  • Suspected outbreak

    Several unrelated people becoming unwell after the same food product should be reported to UKHSA or local health protection teams.

Living with it

Prevention is mostly about a short list of foods.

Four habits that make the biggest difference if you are pregnant, older or immunosuppressed - knowing the risky foods, respecting the fridge, reheating properly and speaking up early.

A quiet reminder

A little caution with food goes a long way.

You do not need to fear every meal - just a short, specific list of higher-risk foods worth avoiding or heating through.

  1. 01 Avoid

    Know the high-risk foods

    Unpasteurised milk and soft cheeses, pâté, smoked fish and pre-packed salads carry the highest risk - check labels if pregnant or immunosuppressed.

  2. 02 Fridge

    Fridge cold does not mean safe

    Listeria can grow slowly even at normal fridge temperatures, unlike most food-poisoning bacteria - use dates, not smell, as your guide.

  3. 03 Reheat

    Heat food through properly

    Thorough reheating until steaming hot kills listeria - useful for ready meals, cold meats and leftovers.

  4. 04 Speak up

    Tell your midwife or GP early

    If you are pregnant and unwell after eating a higher-risk food, mention it straight away rather than waiting to see if it passes.

Frequently asked

Everything we get asked about listeria infection.

Quick answers on food sources, pregnancy risk, notification and treatment.

  • What is a listeria infection?

    Listeriosis is a bacterial infection caused by Listeria monocytogenes, usually picked up from contaminated food such as unpasteurised dairy, soft cheeses, deli meats or pre-packed salads. Most healthy adults get mild or no symptoms, but it can be serious in pregnancy, older age and immunosuppression.

  • Why is listeria more dangerous in pregnancy?

    Listeria has a particular affinity for the placenta, which means it can cross into the pregnancy and cause miscarriage, stillbirth, preterm labour or neonatal infection. This is why pregnant women are advised to avoid specific high-risk foods and to seek prompt assessment for any fever.

  • Can listeria grow in the fridge?

    Yes - unlike most food-poisoning bacteria, listeria can survive and slowly multiply at normal fridge temperatures. This is part of why ready-to-eat chilled foods such as pâté and smoked fish carry a particular risk for vulnerable groups.

  • What foods should pregnant women avoid?

    Unpasteurised milk and soft cheeses, pâté (including vegetable pâté), smoked fish, and pre-packed salads or cold cooked meats that will not be reheated are the main foods to avoid or heat thoroughly before eating.

  • How is invasive listeria infection treated?

    IV amoxicillin or ampicillin, sometimes combined with gentamicin, is first-line treatment. Cephalosporin antibiotics are avoided because listeria has natural resistance to them. Meningitis needs a longer course under specialist care.

  • Is listeriosis notifiable in the UK?

    Yes - confirmed listeriosis is a notifiable disease reported to UKHSA. This allows public health teams to spot clusters, trace contaminated food sources and investigate potential outbreaks.

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