§ Sir Peter EmeryTo ask the Secretary of State for Health how many cases of salmonella infection in human beings have been proved absolutely to have arisen from the consumption of eggs; and in how many cases it was impossible to trace back to an egg or to an egg farm such infection and assumptions made that it originated in this manner.
§ Mr. FreemanThe evidence linking eggs and salmonella infection in man is based on many different kinds of information. It is not often possible to prove absolutely the cause and effect in individual cases—any more than individual cases of cancer of the lung can be proven as due to cigarettes.
Since the beginning of 1988, the PHLS communicable disease surveillance centre (CDSC) has investigated 11 outbreaks (involving at least 759 people) of salmonella infection in which a statistical association with eggs was 282W found. In five of these (involving at least 341 people) there was supporting microbiological evidence. Most of these investigations have been published in the medical literature.
In 1988 and 1989, public health professionals reported to CDSC 76 outbreaks (involving at least 1,257 people) which they attributed to eggs or foods which contained egg.
Egg packaging is required to show certain information, for example, the packaging station number which will assist investigations to trace back eggs implicated in food poisoning outbreaks. However, the packaging may not always be available and, when it is, it is not always possible to identify a producer particularly in those cases where a packing station is handling eggs from more than one source.