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11
A remarkable incidence of multiple cases of typhoid fever occurred in Lambeth
where in one house occupied by two families no less than twelve cases were notified
in the course of August and September, two being fatal. The source of infection
could not be traced. Other instances of multiple cases were:—21 of two cases in
one house, of which 17 occurred in Lewisham ; four of three cases in one house, two
of which occurred in Lewisham, where also in one instance there were five cases in
one house.

Of these cases, seven were fatal, six in Lewisham and one in Penge.
Although the early patients in this series began to sicken about 23rd September,
it was not until more than two weeks later that the serious nature of the outbreak
became apparent. The long incubation period, the insidious onset, and the fact
that the early cases of an epidemic may be so mild that they are at first overlooked,
constitute some of the reasons why it is so difficult to prove definitely the cause
of such an outbreak. The ordinary person has some difficulty in remembering
where he had been, what he had done, and, still more, what food or drink he had
consumed several weeks prior to the onset of his illness, and even supposing that he
does remember, the suspected article of food is seldom available for analysis.
Classifying the 124 notified cases according to the date of their onset, the infection
seems to have been operative first on Saturday, 14th September, and to have
caused, so far as is known, 42 cases; but the same or a similar source of infection
appears to have become active again on or about 26th September and to have caused,
so far as can be ascertained, 61 cases.
A very careful survey of the information available as to the food consumed by
the patients finally fixed suspicion upon the supplies distributed by a certain shop
in the Lewisham area. This hypothesis was strengthened by the discovery that
a patient living in Hitchin had one meal in London on 23rd September at a friend's
house and recollected, not without annoyance, that the meal had only consisted
of cooked ham. This ham was traced to the firm in question. The employees
of the firm were placed under observation and enquiries elicited the fact that one of
the employees had become ill about 9th October and was absent from duty suffering,
as was thought, from influenza. He subsequently had a relapse with haemorrhage
of the bowel and died. A post-mortem examination showed the cause of death
to be enteric fever. This man in all probability was infected by the same source as
the other cases, and was not the original carrier. The evidence strongly suggests
that the outbreak was caused by a "carrier" infecting cooked food, but by the time
the probable source of infection was traced his carrier condition had ceased. It is
regrettable to report that two of the thirteen secondary cases occurred among nurses
in two of the foremost London hospitals to which cases from Lewisham had been
admitted.
The sequence of the cases notified in Lewisham according to date of onset of
illness is set out below. The figures in heavy type show, against the date of onset,
the age of males and the italic figures the age of females, attacked.