Your questions answered: listeriosis

As long as you remain well there is no action that you need to take. The majority of people who are exposed to listeria do not become unwell, and there is no reliable test to detect infection among people who are not unwell. There is no vaccination to provide protection. Should you become unwell with a fever, muscle aches, and gastrointestinal symptoms such as nausea or diarrhoea, you should seek medical attention, particularly if you are in a group that is especially vulnerable to this infection e.g. a pregnant woman or someone with a disease and/or medication that lowers your immunity.

The risk of developing the serious form of listeriosis is low following exposure through the consumption of contaminated food (this is because the majority of listeria bacteria are targeted by the immune system before they are able to cause infection). Because of this, listeriosis is a rare disease in this country, despite the fact that listeria contamination occurs in the food chain at low levels from time to time. Some people are at a higher risk of developing the serious form of disease following exposure, although that risk remains very low. Those most at risk are the unborn babies of mothers who are exposed in pregnancy, newly delivered infants, elderly people and those with an underlying illness that lowers their immunity. Listeriosis, very occasionally, occurs in previously healthy people.

If you are in a high-risk group and have eaten the contaminated product and within 2-3 months become ill with fever, muscle aches, and sometimes gastrointestinal symptoms such as nausea or diarrhoea, you should contact your GP and inform him or her about this exposure.

It is perfectly safe to breastfeed as long as you remain well.

The severe form of listeria infection may develop between a few days and up to two or three months after exposure, and may start with a fever, 'flu-like illness, and/or diarrhoea. There are many other causes of such symptoms, but should you believe that you may have been exposed to listeria infection, and particularly if you are in a group that is especially vulnerable to this infection (see above), then you should tell your doctor about your possible exposure. Severe forms of the disease include septicaemia (infection of the blood) and meningitis.

Listeria infection can be treated with antibiotics.

When infection occurs during pregnancy, antibiotics given promptly to the pregnant woman can often prevent infection of the foetus or newborn. A combination of antibiotics is often used until physicians are certain of the diagnosis. Although very rare, some of the more serious infections can result in death even after prompt treatment. This is most common in the elderly and people with other serious medical conditions, but again this is a rare event.

It is perfectly safe for you to prepare food for others as long as you can follow standard hygienic measures and as long as you are well.

The recent contamination event occurred with pre-prepared sandwiches supplied to hospitals and other outlets. These products have now been withdrawn and will have passed their use by date. Foods associated with transmission are most often ready-to-eat refrigerated and processed foods such as: pre-prepared cooked and chilled meals, soft cheeses, cold cuts of meat, pâtés, preprepared sandwiches and smoked fish. The advice from the Food Standards Agency remains in place that those who are pregnant and are immunosuppressed should avoid consumption of soft ripened cheese, such as Camembert, Brie and other blue-veined varieties, as well as to avoid the consumption of pâté.

The risk of developing listeria infection after consumption of a contaminated product is very small. If you have eaten a contaminated product and do not have any symptoms, we do not recommend that you have any tests or treatment, even if you are in a high-risk group. However, if you are in a high-risk group, have eaten the contaminated product, and within 2 - 3 months become ill with fever, muscle aches, and sometimes gastrointestinal symptoms, such as nausea or diarrhoea, you should contact your GP and/or hospital consultant about this exposure.