Measuring foodborne illness levels

Foodborne illness is caused by the consumption of food contaminated with germs or their toxins.

There are five major foodborne bacteria that, taken together, probably account for the majority of cases of foodborne illness – salmonella, campylobacter, E. coli O157, Listeria monocytogenes and Clostridium perfringens. They are important either because they cause a lot of cases of intestinal illness or because they cause severe disease, or both. Viruses may also cause foodborne disease but they are much more often spread from person to person.

When people get an attack of diarrhoea and vomiting, they tend to think they are ill because of something they ate, but data suggests that at least 50% of cases are not related to food. Even when a foodborne germ such as salmonella or E. coli O157 is found, we can not be sure it has come from food that has been eaten. It may have come from someone else who was ill, a pet or other animal, or an environment contaminated with animal faeces, for example.

This means we can't be sure exactly how many cases of food poisoning there are. Unless people who are suspected of having food poisoning provide a stool sample for testing we do not know if they have one of these foodborne germs. But there are ways in which we can make reasonable estimates of trends and tell whether the number of cases is going up or down.

Although only a minority of cases result in a positive laboratory report, studies have shown that the system provides a reliable indication of trends in salmonella, campylobacter and E. coli O157. Because of its severity, we think that listeria is also picked up well using this approach. The system is probably not so good at detecting Clostridium perfringens, but it is an important cause of outbreaks.

The Agency's success in achieving its target to reduce foodborne illness by 20% over five years will be assessed on the basis of the number of laboratory reports of the five main foodborne bacteria (salmonella, campylobacter, E. coli O157, listeria and Clostridium perfringens) recorded each year over the five year period. We have excluded from this figure the cases reported as having been acquired abroad.

In adopting this approach, we recognise that the baseline figure will include only a small proportion of all the actual cases, since most are not confirmed by laboratory testing. However, in assessing progress towards the target, we only really need a reliable way of monitoring the trend in confirmed laboratory notifications.

Based on the cases reported in 2000, the baseline figure is 65,209.

All cases (including those from food eaten abroad)

	UK	England and Wales	Scotland	N. Ireland
Salmonella	16,987	14,844	1,723	420
Campylobacter	62,867	55,376	6,482	1,009
E.coli O157	1,147	896	197	54
Clostridium perf.	166	124	32	10
Listeria	113	98	11	4
Total	81,280	71,338	8,445	1,497

Cases not thought to have been acquired abroad

	UK	England and Wales	Scotland	N. Ireland
Salmonella	13,122	11,456	1,338	328
Campylobacter	50,773	43,415	6,359	999
E. coli O157	1,035	790	196	49
Clostridium perf.	166	124	32	10
Listeria	113	98	11	4
Total	65,209	55,883	7,936	1,390