Why are we asking this question now?
Salmonella is back in the news, because the Food Standards Agency has found high levels of salmonella in foreign eggs. The Government's food watchdog said that one in 30 boxes of imported eggs had salmonella, a bacterium that can cause nasty - and occasionally fatal - food poisoning. In Spanish eggs, the figure was one in eight. Quite separately, the Government has uncovered the mis-labelling of millions of battery-farm eggs as free-range.
Where does Edwina Currie come into it?
Although the British egg industry insists its eggs are safe to eat, the FSA's salmonella survey brought back memories of Edwina Currie's infamous comments in the late 1980s which plunged the egg industry into crisis. On 3 December 1988, the outspoken junior health minister told ITN: "Most of the egg production in this country sadly is now infected with salmonella." Sales of eggs plummeted 60 per cent overnight. The loss of revenue forced farmers to slaughter four million hens and destroy 400 million unwanted eggs.
What happened to Ms Currie?
She had a torrid time. Ms Currie had spoken out because cases of Salmonella enteritidis, associated with poultry production, had almost trebled in a year. But the egg industry rubbished her comments. British Egg Industry Council said the risk of getting salmonella from eating an egg was less than one in 200 million and took out adverts in all the newspapers headed "Eggs. The facts". Officials at the Ministry of Agriculture were reported to be very "angry" at their health colleague's remarks. Amid the crisis, the government mounted a multimillion-pound compensation package for egg producers. Margaret Thatcher stated her views. "I had eggs for breakfast," she said. Ms Currie resigned on 17 December.
What is salmonella?
The salmonella bacterium was first found in pigs by the 19th-century American veterinary pathologist, Daniel Elmer Salmon. It lives in the stomach and intestines of animals and humans. The chances of catching it from eating an egg are slim but the disease can be nasty, especially for vulnerable groups like children and pensioners.
A sufferer may experience fever, stomach pain, diarrhoea, nausea or vomiting. Most patients recover in a week but it can be deadly, particularly if it spreads into the bones or blood. For such vulnerable groups the Health Protection Agency says that salmonella can be "extremely unpleasant".
Are British eggs now safe to eat?
British eggs do have salmonella. But very few. The latest FSA study, in 2003, found salmonella in 0.3 per cent of UK eggs. There was no difference between battery, free-range or organic eggs. Salmonella is almost always killed in cooking. Even then, a fit person may fight off an infection. Alas, the British egg industry was not always so healthy.
Although Ms Currie undoubtedly exaggerated the degree of salmonella in British egg production, the industry did have a problem and was giving too many people food poisoning. Farms tried to clean up but the real breakthrough came in 1998 when the vaccination of hens for salmonella was introduced at farms backing the new British Lion mark. All the big egg producers put the marks on their eggs. From 1998 there have been falls almost every year in the number of human cases of Salmonella enteritidis. In 1997, there were 22,254 cases. In 2005, there were 6,677. Yesterday a spokesman for the British Egg Information Service said: "British eggs are about as safe as you can eat."
What about foreign eggs?
A survey by the European Food Safety Agency this year found far higher rates of salmonella on the Continent than in Britain. Checks were carried out at 5,317 hen-laying farms in 23 countries; those in the EU and Norway. The proportion of UK egg farms with salmonella was 11.9 per cent, the sixth lowest. Swedish, Finnish and Danish farms had extremely low figures, between 0 and 3 per cent, probably because of the cold.
But salmonella was found in 73 per cent of Spanish farms, 77 per cent of Polish farms and 79 per cent of Portuguese farms. In France the figure was 17 per cent, in Germany 28 per cent and in Italy 30 per cent. The actual level of salmonella in eggs from these farms is far lower. The Food Standards Agency's testing of 1,744 boxes of imported eggs on sale in London and the North-west, found salmonella present in one in 30 boxes.
What does the Government say?
Cook eggs thoroughly. The Food Standards Agency advises cooking eggs until the white and yolk are solid. It especially warns against consumption of raw eggs by anyone who is very young, elderly, pregnant or already unwell, because their chance of contamination is greater. Raw eggs are used in many home-cooked and restaurant dishes such as mayonnaise, Béarnaise and hollandaise sauces, salad dressings, ice cream, icing, mousse and tiramisu and other desserts.
Does that mean we can't eat mayonnaise or tiramisu?
Not necessarily, just be careful, particularly if you have a weak immune system. Food manufacturers tend to use safe pasteurised egg for raw egg dishes. The FSA also advises caterers and home cooks to use pasteurised eggs, which are available in supermarkets. In restaurants, the FSA suggests diners ask the waiter whether the eggs have been pasteurised.
The advice was repeated at the height of the bird flu scare earlier this year because of the theoretical risk that bird flu can spread to humans through raw eggs. The FSA advises eggs be stored in the fridge away from other foods and should always be eaten by their best-before date. Not all eggs have best-before dates. But all eggs carrying the Lion Mark - 85 per cent of the country's annual 8.5 billion eggs - have them.
Did Ms Currie help?
Salmonella levels in the late 1980s were too high. By making her comments, she highlighted the problem, which was eventually solved - in Britain at least - by the introduction of vaccination. But she caused an unnecessary crisis in the poultry industry and a pointless panic among the public.
In 2006, eggs are far safer. Doing a few things can make their consumption safer still: buy Lion Mark British eggs, use them before the best-before date and don't eat dishes with raw eggs. Or take a risk and accept that you might, just might, get food poisoning.
Are eggs potentially threatening to human health?
* Although the incidence of salmonella in eggs can be reduced, it cannot be eliminated
* People are not going to stop eating dishes such as mayonnaise and tiramisu, which require raw eggs in their preparation
* Although salmonella has been drastically reduced in the UK, a large number of imported European eggs still have the bacterium
* If you cook your eggs thoroughly, you will not have a problem as cooking kills the salmonella
* Recipes that require raw eggs can still be followed, as long as the cook uses pasteurised eggs
* Not since vaccinating chickens reduced the incidence of salmonella to very low levels of riskReuse content