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Bacteriology. The organism responsible for one family outbreak
of three cases was Salmonella typhimurium, for another family outbreak
of three cases the coagulase—positive staphylococcus, and of a school
canteen outbreak of thirty-one cases CI. Welchii. The agent was not
discovered in six outbreaks involving in all 19 cases. Salmonella typhimurium
was recovered in five of the 19 instances of single cases of food
poisoning.
The Position Nationally. The following information has been
abstracted from a report of the Public Health Laboratory Service on
Food Poisoning in England and Wales in 1957:—
1. The number of incidents, 7,071 was a reduction of 8% on the figure
for 1956 and of 21% on that of 1955. The reduction was mostly in
incidents due to S. typhi-murium and in those where no cause was found.
Incidents due to staphylococci and to CI. Welchii were much the same in
number. Incidents due to Salmonellae other than S. Typhi-murium
increased; this is a continuation of an increase seen each year since
1954 and is seen in family outbreaks and sporadic cases but not in the
general outbreaks.
2. The 7,071 incidents comprised 473 general outbreaks, 501 family
outbreaks and 6,097 sporadic cases. Over 15,100 persons were reported
as cases in these incidents, some 6,000 more than the number of cases of
food poisoning reported by the Registrar General.
3. Salmonellae were responsible for 59% of all incidents and for 95%
of incidents due to recognised pathogens.
4. The maximum incidence was in the summer months, reflecting the
close relation between atmospheric temperature and the growth of
bacteria in food.
5. 69% of outbreaks in which contaminated food was mentioned were
associated with processed and made-up meats.
6. In the general outbreaks for which information was available the
canteen holds first place, followed by hospitals and then restaurants. The
canteen outbreaks in which a pathogenic microbe was identified were
nearly all due to CI. Welchii; but in hospitals most outbreaks were
associated with salmonellae, an indication of cross-infection rather than
spread of infection via contaminated food.
7. The most reasonable explanation of the rise and fall of different
types of salmonellae organisms is changes in the types contaminating
the widely distributed food The control of egg and egg products is
therefore likely to make a substantial reduction in human salmonellosis.
Processed and made-up meats were mentioned as the vehicles of
infection in about half the outbreaks of salmonellosis traced to a specific
item of food. Analysis of the foods over the past four years shows that
nearly two-thirds of the incriminating processed and re-heated meat
dishes were pork pies, brawn, sausages and cold pork. Sausages and brawn
are frequently made from pig meat. Pig meat therefore remains, as in the
Past, a frequent source of salmonellae. Galton, etc. found that infected
Pigs detained at an abattoir might infect 90% of the pigs with which they