Overview

Listeriosis is a rare infection caused by bacteria called listeria. It usually goes away on its own, but it can make some people seriously ill.

How you get listeriosis

Listeriosis is usually caused by eating food contaminated with Listeria bacteria.

Listeria can contaminate a wide range of foods, but most infections are caused by eating chilled, ready-to-eat foods, such as:

• cold, cooked sliced meats and cured meats
• smoked and cured fish – including in sushi
• cooked shellfish
• soft mould-ripened cheeses, such as camembert and brie, and blue-veined cheeses
• pâté
• pre-prepared sandwiches and salads
• pre-cut fruit (e.g., pre-packed melon slices)
• unpasteurised milk
• dairy products made from unpasteurised milk

These foods do not always cause listeriosis. If you have eaten them recently, you do not need to do anything unless you get symptoms of the infection.

Although it's less common, you can also catch listeriosis from:

• someone else who has it – for example, if you eat food they've handled when they've not washed their hands
• close contact with farm animals – especially sheep and cows that are giving birth

Symptoms of listeriosis

In most people, listeriosis has no symptoms or only causes mild symptoms for a few days, such as

• a high temperature 
• aches and pains
• chills
• feeling or being sick
• diarrhoea

If you're pregnant, you may also have a stomach ache or notice your baby moving less than usual.

Babies with listeriosis may also be irritable and feed less than usual.

Risks of listeriosis

Listeriosis is not usually serious for most people.

But some people have a higher risk of serious problems, including:

• people who are pregnant
• newborn babies
• people with a condition that weakens their immune system, such as cancer, diabetes, liver disease or kidney disease
• people having treatment that weakens their immune system, such as chemotherapy or steroid tablets

Older people are also at higher risk of getting seriously ill from listeriosis, and this risk increases with age.

If you get listeriosis while you're pregnant, there is a risk it could cause miscarriage or stillbirth.

In babies and people with a weakened immune system, listeriosis can sometimes lead to serious and life-threatening problems such as sepsis or meningitis.

Ask for an urgent GP appointment or get help from NHS 111 if:

• you're pregnant and think you have listeriosis
• you have a condition that weakens your immune system (like cancer or kidney disease) and think you have listeriosis
• you're having treatment that weakens your immune system (like chemotherapy or steroid tablets) and think you have listeriosis
• you think your baby might have listeriosis

You can call 111 or get help from 111 online.

If you're pregnant, you can also call your midwife for advice.

Call 999 or go to A&E if you or your child:

• have a severe headache and stiff neck
• find it uncomfortable to look at bright lights
• have a fit (seizures)
• feel suddenly confused
• feel very sleepy or difficult to wake
• have a rash that does not fade when a glass is rolled over it – the rash may be blotchy, like bruises or small red pinpricks

These could be symptoms of meningitis caused by listeriosis, which needs to be treated in hospital straight away.

Treatment for listeriosis

For most people, listeriosis is mild and gets better in a few days.

You can usually look after yourself at home by resting and drinking plenty of fluids.

If you're at a higher risk of getting seriously ill (for example, you're pregnant or have a weakened immune system), you may need antibiotics.

Find out how to treat diarrhoea and vomiting at home

How to avoid listeriosis

There are some simple things you can do to reduce your risk of getting listeriosis.

Do

• keep chilled, ready-to-eat foods cold – try to make sure your fridge is working properly and is set to 5C or below
• eat ready-to-eat foods within 4 hours of taking them out of the fridge
• eat, cook or freeze foods by their use-by date
• follow storage instructions on food labels and use opened food within 2 days (unless the packaging says otherwise)
• keep raw and ready-to-eat foods separate
• follow the cooking instructions on packaging when applicable, and cook or reheat (including frozen vegetables) until they are steaming hot right through 
• wash your hands regularly with soap and water

Foods to avoid if you're at risk

Pregnant women and people who have a weakened immune system are more likely to suffer severe symptoms from listeria infection and are advised to avoid eating ready-to-eat cold-smoked or cured fish products, such as smoked salmon or gravlax (unless cooked until steaming hot).

If you're pregnant you should avoid eating foods that have the highest risk of causing listeriosis.

These include:

• some soft cheeses (including brie and camembert) – unless cooked until steaming hot
• all types of pâté – including vegetable pâté
• unpasteurised milk or dairy products
• any undercooked food

Find out which foods to avoid during pregnancy

If you're pregnant, you should also avoid close contact with farm animals that are giving birth or have recently given birth.