17721 Listeriosis

Overview

Listeriosis is an infection caused by the bacterium Listeria monocytogenes. It usually comes from eating contaminated food. In healthy people it often causes only mild symptoms, but it can be serious for pregnant women, newborns, older adults, and people with weakened immune systems.

No, listeriosis is rare compared with many other foodborne infections. In the UK, around 160 to 200 cases are reported each year.

It can affect anyone, but most severe infections occur in pregnant women, newborns, adults over 65, and people with a weakened immune system from conditions such as cancer, diabetes, or kidney disease, or from certain medicines.

Symptoms

Common symptoms

• No symptoms at all in some people
• Mild fever
• Muscle aches
• Nausea or diarrhoea
• Tiredness or feeling run down
• Sometimes a mild headache

Symptoms in children

• Fever and chills
• Vomiting or stomach cramps
• Irritability or unusually fussy behaviour
• Poor feeding in babies
• Tiredness or low energy

Symptoms in older adults

• Confusion or a change in mental state
• Stiff neck
• Loss of balance or difficulty walking
• Severe headache
• Seizures (fits)

Causes

Main causes

• Eating food contaminated with Listeria bacteria
• Unpasteurised milk and dairy products made from unpasteurised milk
• Soft cheeses such as feta, brie, camembert, and blue-veined cheeses
• Chilled, ready-to-eat foods like deli ham, paté, and smoked seafood
• Pre-packaged leafy salads and pre-cut fruit that have not been washed properly

Risk factors

• Pregnancy, especially in the third trimester
• Age over 65
• A weakened immune system from cancer treatment, organ transplant, or conditions like HIV
• Long-term conditions such as diabetes or kidney disease
• Taking medicines that reduce stomach acid
• Being a newborn baby

When to see a doctor

See a doctor urgently if:

• A temperature above 38°C (100.4°F) that lasts more than 24 hours
• Severe headache or a stiff neck
• Confusion or feeling unusually drowsy
• In pregnancy, any fever or feeling unwell after eating a high-risk food
• Vomiting that keeps you from keeping fluids down

Book a routine appointment if:

• You have recently eaten a food that can carry Listeria and you feel unwell, even with mild symptoms
• You are in a high-risk group and have any flu-like symptoms
• You have had diarrhoea that lasts more than 3 days

Diagnosis

Your doctor will ask about your symptoms and what you have eaten recently. Because listeriosis can be serious, they may arrange tests to confirm it.

Tests that may be done

• Blood test to look for the bacteria
• Spinal tap (lumbar puncture) if the bacteria may have reached your nervous system
• Urine or stool tests in some cases
• Listeria testing of amniotic fluid or blood during pregnancy if needed

What to expect at your appointment

The test results may take a few days because the bacteria need time to grow in the lab. If you are very unwell, treatment may be started before the results come back.

Treatment

Most mild cases need no specific treatment, and the infection clears in a few days. For people at higher risk, or if the infection has spread, treatment with antibiotics is needed, usually given in hospital.

Self-care at home

• Get plenty of rest
• Drink fluids little and often to prevent dehydration
• Monitor your temperature with a thermometer
• Avoid alcohol and heavy meals
• Do not take any medicines without checking with your doctor or pharmacist first

Medical treatments

Antibiotics are the main treatment for listeriosis. They are usually given directly into a vein (intravenously) in hospital for two to four weeks, especially for pregnant women, older adults, or people with a weakened immune system. This approach is effective, and in pregnancy it greatly reduces the risk to the baby.

When is surgery considered?

Surgery is not a usual treatment for listeriosis. In very rare cases, an abscess (a pocket of infection) may need to be drained, but this is uncommon.

Living with this condition

If you are being treated for listeriosis, follow your healthcare team’s advice closely. Get enough rest, drink fluids, and keep track of your temperature. If you are pregnant, you will likely have extra checks on your baby’s wellbeing.

Lifestyle tips

• Wait until you feel fully better before returning to work or vigorous activity
• Wash your hands often, especially after using the bathroom and before preparing food
• Avoid high-risk foods while your body recovers
• Follow up with your doctor if symptoms return after treatment

Diet and exercise

A light diet such as soups, toast, rice, and bananas is often easier to manage while your stomach is settling. Gentle movement, like short walks, can help you feel better as you recover, but do not push yourself until you have more energy.

Mental health and emotional wellbeing

It is normal to feel anxious, especially if you are pregnant or caring for a newborn. Worry about the infection can be stressful. Talk to your healthcare team about any fears you have, and lean on loved ones for support.

Prevention

Yes, most cases can be prevented with careful food hygiene and by avoiding foods that are more likely to carry Listeria, especially if you are in a high-risk group.

Vaccines

There is no vaccine for listeriosis, but safe food practices offer strong protection.

Screening programmes

No routine screening test is used for listeriosis, but pregnant women are given food safety advice so they know which foods to avoid.

Complications

If left untreated

• Bacteraemia – infection in the bloodstream
• Meningitis – inflammation of the membranes around the brain and spinal cord
• Sepsis – a life-threatening reaction to infection
• In pregnancy: miscarriage, stillbirth, preterm birth, or infection in the newborn
• Endocarditis – infection of the heart’s inner lining (rare)

Long-term outlook

With prompt antibiotics, most people with severe listeriosis recover fully. Healthy people usually recover in a few days without treatment. In pregnancy, early treatment protects the baby and greatly improves the outcome. Although it can be serious, effective treatment is available and most people make a full recovery.

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