Listeriosis is an infection that usually develops after eating food contaminated by listeria bacteria.
In most people, listeriosis is mild and causes symptoms including a high temperature (fever), vomiting and diarrhoea. These symptoms usually pass within three days without the need for treatment.
However, in rare cases, the infection can be more severe and spread to other parts of your body, causing serious complications, such as meningitis. Common signs of severe listeriosis include a stiff neck, severe headache and tremors.
Read more about the symptoms of listeriosis.
Where is listeria found?
Listeria bacteria have been found in a range of chilled "ready-to-eat" foods, including:
- pre-packed sandwiches
- soft cheeses – such as Brie or Camembert, or others with a similar rind
- soft blue cheese
- cooked sliced meats
- smoked salmon
The bacteria may also be passed on through contact with the stools of infected animals or human carriers.
Read more about what causes listeriosis.
Looking after yourself at home
Over-the-counter painkillers, such as paracetamol and ibuprofen, can offer some relief for muscle pain and fever, if you need it.
If you have diarrhoea, it's important to drink plenty of fluids to replace those that have been lost. Read about the treatment of diarrhoea.
If you've been vomiting or feeling sick, it should be fine to avoid eating for a short while. However, make sure you continue drinking fluids, and eat as soon as you can. Eat small, light meals and avoid fatty or spicy foods.
Contact your GP if your symptoms don't improve within a few days.
Some people are particularly vulnerable to severe listeriosis.
- people over 65 years of age
- pregnant women and their unborn babies
- babies less than one month old
- people with a weakened immune system, such as those with HIV/AIDS or receiving chemotherapy
Seeking medical help
Seek medical help if your symptoms are severe (see below).
Listeriosis is usually diagnosed with a blood test. If it's thought that the infection has spread to the nervous system, further tests may include an MRI scan and a lumbar puncture.
Pregnancy and children
If you're pregnant and show signs of listeriosis, or if you have a young child who shows signs of the illness, seek immediate medical advice.
If you develop listeriosis during pregnancy, you'll be given antibiotics to help prevent the infection spreading to your baby. You may also be given additional ultrasound scans to assess the health of your baby.
Treatment for listeriosis in infants is the same as for adults, although it's usually recommended that infants are kept in an intensive care unit (ICU) as a precaution.
Treating severe listeriosis in adults
If listeriosis spreads into your blood (septicaemia) or your central nervous system, you'll be admitted to hospital to receive injections of antibiotics (intravenous antibiotics) while your health is carefully monitored.
The length of time you'll need to spend in hospital depends on whether the infection has spread from your blood or nervous system to other organs, such as your brain.
Most people with severe listeriosis require at least two weeks of treatment with intravenous antibiotics. However, in the most serious cases, at least six weeks of treatment may be needed.
The best way to reduce your chances of developing listeriosis is to ensure you always practise good food hygiene. For example, you should:
- not use food past its "use by" date
- follow storage instructions on food labels
- make sure that the temperature of your fridge is 0C to 5C
- cook food thoroughly
If you're in a high risk group for listeriosis – for example, if you're pregnant or you have a weakened immune system, avoid eating some foods, such as soft mould-ripened cheese or pâté.
Read more about preventing listeriosis.
Listeriosis and pregnancy
Pregnant women are at particular risk of developing listeriosis. This is because the body's natural defences against the listeria bacteria are weaker during pregnancy.
Pregnant women are almost 20 times more likely to develop listeriosis compared with the rest of the population.
A listeria infection in pregnancy doesn't usually pose a serious threat to the mother’s health. However, it can cause pregnancy and birth complications, and can result in miscarriage.
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