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CHAPTER XXXIII.
Special Report submitted by the Medical Officer of Health during the year 1911.
I.—Report by Dr. Hamer on an Outbreak of Typhoid Fever in London in September, 1911.
On Thursday, 14th September, the notification list showed marked increase in the number
of cases of typhoid fever, there being 30 cases notified during the week ending Saturday, 9th September,
in Finsbury, as compared with 0, 0, 1, 0 and 1 in the preceding five weeks.* On proceeding to
Finsbury Town Hall it was ascertained that the outbreak was an explosive one, most of the patients
having sickened during the last week in August or the first week in September. In families in
which multiple attacks had occurred, the interval between the dates of sickening of the several
relatives in question was quite short. (See particular as to dates of onset in appended Table.) Dr.
Thomas, Medical Officer of Health for Finsbury, and I analysed the information available and, prima
facie, it was obvious that some suspicion attached to two articles of food, viz., ice cream and fried
fish. Milk, to which of course consideration was in the first instance given, was clearly not at fault.
Approximately one-third of the total number of sufferers (at that time already amounting to more than
40), might, it transpired, have consumed milk supplied by a particular vendor, but with regard to at
least 24, i.e., more than half the total number, the possibility of consumption of milk retailed by
this vendor could be excluded. There still remained a remote chance that some of the 24 sufferers
who had not partaken of the milk of this vendor, as milk, might have consumed milk, derived from
one and the same source as that supplying the particular vendor, in the form of ice cream. Careful
enquiry as to the sources of milk supply of the ice cream vendor who had sold ice cream to a considerable
number of the sufferers did not, however, show that he had obtained any milk from the
source supplying the suspected milk vendor. Even if the supplies of the milk vendor and the ice
cream vendor had been, unknown to either of them, derived from some common source, there
remained at least 9 out of 40 sufferers (within the area of the explosion) who had not partaken of
either the suspected milk or the suspected ice cream. Moreover, it was learnt later that 5 or 6 other
sufferers living within the area, and at least 6 sufferers living outside the area of the explosion, but whose
illness was in all probability contracted within the area, had not partaken of either the suspected
milk or the suspected ice cream. This outstanding 20 or 21 cases could not, having in view dates
of onset of attack, be ascribed to contact with preceding cases. It was, further, in the highest degree
improbable that, at the time of occurrence of the explosive outbreak, 14 or 15 other cases (or, including
the cases living outside the area, 20 or 21 other cases) would arise in the affected area quite
independently of the cases constituting the explosive outbreak itself.
It was noted that some 5 or 6 of the total number of sufferers living within the area had been
away from London at a time when they might conceivably have been infected. On the other hand,
the dates of going away from, and of returning to, the area permitted of these 5 or 6 sufferers having
been infected within the area itself. The possibility of contamination of a water main was, of
course, considered, but the distribution of the cases lent no support to such an hypothesis, and it may
here be noted that the age distribution of the sufferers from typhoid fever in this outbreak was quite
an exceptional one, children and young adults were affected in altogether undue proportion, indeed all
the persons attacked, with only four exceptions, were between 5 and 26 years of age. It will be
seen later, moreover, that sufferers were in the main drawn from a particular social class. This notable
selection for attack of persons at certain ages, and, further, of persons of a particular social class
practically negatived the possibility of the outbreak having been due to water or milk. On the other
hand, it strengthened a suspicion which was now increasingly entertained that some such medium as
ice cream or fried fish was in question.
Enquiry was made as to other possible sources of infection, e.g., shellfish or watercress;
very few of the sufferers had consumed either of these articles of food. At the time of the outbreak
the mussel season had barely commenced, and as a matter of fact the sufferers had only quite
exceptionally eaten shellfish. The same statement is true with regard to watercress. Enquiry was
also made as to common use of swimming baths, but again with a negative result.
It was now felt that the important point to determine, in the first instance, was the proportion
of sufferers who had partaken, within the possible period of incubation, of one or other of the two
foods, upon which suspicion was now seen especially to fall, viz., ice cream and fried fish. All the
patients who could be found, and who were able to answer, were seen and questioned, and the results
now to be summarised were ultimately obtained. For the purposes of the enquiry an area included
within a radius of one-twelfth of a mile (440 feet), from a centre around which the cases were aggregated,
was defined as the area of the explosion. The centre of the area was fixed at a point midway between
the shops of the vendors of fried fish and ice cream referred to below as X and Y.
* The notifications in London as a whole were 73 in the week ending 9th September as compared with 17,
12, 17, 14 and 28 in the preceding five weeks.
12532 l 2