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(e) Foods involved, with number of outbreaks associated with each food.
In no case was it possible definitely to identify a particular foodstuff as being the source
of infection. Investigation into the two largest outbreaks, involving 71 and 10 cases
respectively, pointed to the possibility of a human carrier being responsible.
The most extensive outbreak occurred at the nurses' home of a large hospital, where 71 cases reported
sick and were treated in bed. Four more were known to have been taken ill at home. The causative
organism was salmonella typhi-murium. With two exceptions all the cases had taken food prepared
in the nurses' home kitchen at either lunch or supper on the 24th September. The two exceptions had
eaten from the same kitchen on the 23rd September, but had had no meals there on the following day.
Conversely, many of those taken ill had not taken food on the 23rd September, so the inference was
that there was minor contamination of the food served on the 23rd September, and gross contamination
on the 24th September. In addition to the cases that reported sick, there were many who had minor
symptoms not sufficient to cause them to report sick. No item of food, however, could be discovered
which was common to the meals on both days other than such commodities as dried milk, flour and
rice. The overwhelming majority of cases reported sick early on the 26th September, having been
taken ill during the previous night. Many had felt slightly unwell on the afternoon of the 25th
September. The kitchen was inspected on the morning of the 26th September, but all food prepared
on the 24th September had either been consumed or thrown away. Samples of it were therefore
not available for laboratory investigations. Food served on the 24th September included shepherd's
pie and rissoles at lunch and supper respectively and trifle at both meals, and it seemed likely from
enquiry of the patients that one of these main dishes was the vehicle of infection. The meat from which
the dishes were prepared was fresh and bought in bulk from Smithfield and supplies of it had gone
to the other kitchens of the hospital, none of which was affected by the outbreak. The evidence
pointed overwhelmingly to contamination of food by some agent in the nurses' home kitchen itself.
Specimens of dried milk, flour and rice and swabs from pots and pans were examined at the Public
Health Laboratory at Colindale and all proved to be negative. Dried milk was also tested in the
hospital laboratory with a similar result. Search was made for rodent droppings in both the kitchen
and the corridors adjoining but none was seen. It therefore seemed likely that a human carrier in
the kitchen may have been the cause of the outbreak. All 22 persons employed there submitted stools
for laboratory investigation and no fewer than six were found to carry salmonella typhi-murium.
None admitted to having had diarrhoea or illness previous to the outbreak or to having been in
contact with a diarrhoea case at their home. Unfortunately, however, all the kitchen staff had the
same meals as the affected nurses and although none of the 22 had symptoms it is possible that the six
referred to were contaminated by those meals but were thus not the original carriers. All were
temporarily suspended from working in the kitchens until they ceased to be carriers. As to the
clinical features of the outbreak, the common onset was profuse diarrhoea and some vomiting
associated with pyrexia up to a temperature of 103°, often with intense headache and severe
lumbo-sacral pain. The majority became afebrile in 2-3 days and symptom-free inside a week. Six
cases, including four who showed signs of severe toxaemia, were treated with Chloromycetin, in the
dosage recommended for typhoid fever, with what appeared to be marked beneficial effect. The
pyrexia, diarrhoea and headache all ceased within 24-36 hours of administration of the drug and did
not recur. Precautions to prevent spread and recurrence of the outbreak were taken. For example,
stocks of dried foods in the larder of the nurses' home were taken out of use until proved
bacteriologically harmless. Kitchen staff were tested as already indicated, and the need for
care and cleanliness was emphasised in general instructions to all nurses and kitchen workers. All
nurses who showed the slightest symptoms were suspended from work in the maternity and children's
wards and employed on other duties ; this mainly because nurses in these departments have to
undertake bottle and infant feeding duties. It so happened that the hospital sub-basements had
been de-ratted with good effect about a week prior to the outbreak, since when no rats had been
found. No fresh cases of food poisoning were subsequently reported.
The outbreak involving 10 cases occurred among the guests at a wedding reception held in May at
an address outside the Borough, at which about 250 people (mainly Cypriots) were present. Ten
cases were notified from the eastern end of the Borough, and cases were also reported in other areas.
Three of the St. Marylebone cases were removed to hospital, and bacteriological examination of
faeces subsequently showed that all three patients—a woman aged 70 years, her grandson aged 7
months, and a boy aged 2½ years—were harbouring organisms of the salmonella aertrycke type. The
food provided at the wedding breakfast was contributed by various persons attending the reception
and was all consumed except some cake which was examined bacteriologically and proved to be sterile.
In view of this and the fact that some of the guests, including the bride's mother, returned to Cyprus,
there was little prospect of identifying the source of the outbreak, though there appeared to be a
possibility that one of the persons who prepared fcod may have carried the infection.