I've heard listeria is on the increase. What can I do to stop getting ill?

Listeria causes a relatively rare form of food poisoning, which rarely affects healthy people, but can cause serious illness in certain groups of people, such as pregnant women, unborn and newborn babies and people with reduced immunity. Illness from listeria has been associated with eating certain chilled foods that are ready to eat.

Over the past few years there has been an increase in illness from listeria, mostly in people over 60 who have weakened immune systems. These people might:

• have had a transplant
• be taking drugs that weaken the immune system
• have an illness that weakens the immune system, such as leukaemia or lymphoma

If you fall into one of these groups, it's more likely you'll pick up an infection, so you should try to avoid cheeses such as Camembert, Brie or chevre (a type of goats' cheese), or others that have a similar rind, soft blue cheeses, and all types of pâté, including vegetable pâté. You should also avoid these foods if you're pregnant.

You can help stop listeria growing on your food by keeping chilled foods out of the fridge for the shortest time possible and not using food after its 'use by' date. Also, make sure you follow the storage instructions on the food label.

But don't forget, you should always wash your hands and clean work surfaces, utensils and chopping boards, before touching food. This will help protect you from listeria and other harmful germs.

How long can food poisoning bacteria live on utensils?

If a knife has been used to open a packet containing chicken then put back into the drawer could the germs spread onto other utensils?

The length of time that food poisoning bacteria can survive on utensils varies according to a number of factors. The only way you can be sure that a utensil is safe to use is by washing it thoroughly in warm water after every use.

You should not put a knife back in the drawer when it has been in contact with food, particularly raw meat or poultry, without washing it first. Otherwise, bacteria could spread to other items in the drawer, or survive on the knife and get onto food the next time you use it.

Can I get salmonella from mayonnaise?

Foods such as homemade mayonnaise, ice cream, cake mix and mousses can contain raw eggs and therefore carry the risk of salmonella.

Commercial products are made using pasteurised egg, which is egg that has been heat-treated to kill bacteria, including salmonella. Commercial products may also contain an acidifying agent which will kill bacteria.

Symptoms of salmonella infection include diarrhoea, fever, vomiting and severe abdominal pain. You can be ill for up to three weeks and people may continue to carry the organism for up to 12 weeks or longer after the symptoms have subsided.

Normally, relatively large numbers of bacteria are required to cause illness in healthy adults, but vulnerable groups, such as the very young, the elderly and immuno-compromised, can be infected by lower numbers.

The Food Standards Agency's advice is that people should avoid eating raw eggs, or uncooked foods made from them, and that elderly people,babies, toddlers, pregnant women and people who are already unwell should eat eggs that have been cooked until the white and yolk are solid.

You can reduce the risk of food poisoning from eggs by:

• checking eggs are clean and not cracked when you buy them
• keeping eggs in the fridge
• using eggs within the 'best before' date
• washing your hands, utensils and kitchen surfaces before and after contact with eggs or foods containing them