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 \u2013 including in sushi
• cooked shellfish
• soft mould-ripened cheeses (such as camembert and brie) and blue-veined cheeses
• p\u00e2t\u00e9
• pre-prepared sandwiches and salads
• pre-cut fruit (such as pre-packed melon slices)
• unpasteurised milk
• dairy products made from unpasteurised milk

These foods do not always contain listeria. 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 \u2013 for example, if you eat food they've handled when they've not washed their hands
• close contact with farm animals \u2013 especially sheep and cows that are giving birth

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.

Listeriosis is not usually serious for most people.

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

• anyone who is 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.

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• \n you're pregnant and think you have listeriosis\n
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• \n you have a condition that weakens your immune system (like cancer or kidney disease) and think you have listeriosis\n
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• \n you're having treatment that weakens your immune system (like chemotherapy or steroid tablets) and think you have listeriosis\n
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• \n you think your baby might have listeriosis\n
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\n You can call NHS 111 or\n \n get help from 111 online\n \n .\n

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

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• \n have a severe headache and stiff neck\n
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• \n find it uncomfortable to look at bright lights\n
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• \n have a fit (seizure)\n
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• \n feel suddenly confused\n
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• \n feel very sleepy or are difficult to wake\n
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• \n have a rash that does not fade when a glass is rolled over it \u2013 the rash may be blotchy, like bruises or small red pinpricks\n
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\n These could be symptoms of meningitis caused by listeriosis, which needs to be treated in hospital straight away.\n

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.

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

• keep chilled, ready-to-eat foods cold \u2013 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 any cooking instructions on packaging, and cook or reheat (including frozen vegetables) until they're steaming hot right through

• wash your hands regularly with soap and water

If you're pregnant or have a weakened immune system, you should 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 also avoid eating other foods that have the highest risk of causing listeriosis.

These include:

• some soft cheeses (including brie and camembert) \u2013 unless cooked until steaming hot
• all types of p\u00e2t\u00e9 \u2013 including vegetable p\u00e2t\u00e9
• unpasteurised milk or dairy products
• any undercooked food

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

Listeriosis does not always cause symptoms. If it's mild, it can cause flu-like symptoms including a high temperature, chills and diarrhoea.

Listeriosis is usually caught from contaminated food. It's also possible to catch it from someone else who has it or from contact with farm animals.

Listeriosis can cause serious problems for some people, such as a miscarriage if you're pregnant or sepsis if you have a weakened immune system.

Most people with listeriosis will get better after a few days at home. People at risk of getting more seriously ill may need antibiotics.

If you're pregnant, you can reduce your risk of getting listeriosis by avoiding certain foods, including p\u00e2t\u00e9 and some uncooked soft cheeses.