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104
Annual Report of the London County Council, 1910.
In Islington cases 31, 32a, 37 and 38 obtained fried fish from a common source, a shop J. If
they were fish-infected cases it will be observed from the time of their occurrence, that they belong
to the later of the two infections already referred to. In Stepney it will be seen (See notes on Diagram)
that three or four of the cases included in the horizontal shaded section were possibly cases of fish
infection. Nos. 36 and 42 obtained fried fish from a common source, and 37 was probably infected
by fish from shop S.
A word remains to be said concerning certain cases in which the onset occurred in the first few
days of August. It is possible in the light of subsequent events, that two or three of the cases
developing at that time in the following boroughs, viz. : Bethnal Green (market street a, case 1);
Islington (shaded section, cases 2 and 3); Islington (stall L, cases 4 and 5); Finsbury (shop M, case 1);
were really due to infected fish distributed late in July, i.e., some time before the date of distribution
of the fish causing the main explosive outbreak.
It must, of course, be borne in mind that, in those instances in which a retail source of supply
of fish was situated near the boundaries of two or more boroughs, it may have supplied sufferers in
more than one borough. (See Diagram.) Thus source a supplied cases in Bethnal Green and
Stepney; source b, cases in Bethnal Green, Shoreditch and Hackney; source d, supplied cases in Bethnal
Green and Poplar; and source X supplied cases in St. Pancras and Holborn.
It will be noted that the source from which fish was obtained was sometimes a fried fish shop,
in other instances a shop or stall in a market street, or a perambulating coster's barrow. Wherever
a fried fish shop was the common source it will be seen that the numbers indicating the cases are all
ringed around. The circle signifies that these sufferers were ascertained to have purchased the fish
in the fried condition. Where, however, the suspected retailer, who supplied all the sufferers in the
group, sold the fish wet, it was often found that no history to the effect that fried fish had habitually been
purchased could be obtained. The point is an important one, affording as it does corroborative evidence
of the correctness of the fish hypothesis (e). It will be noted further that 32 out of 96, i.e., some 34 per
cent. of those sufferers who formed the residuum of cases in each borough were not fried fish eaters.
In previous enquiries concerning typhoid outbreaks attributed to fried fish, a considerable
sample of the population of the affected area has been made the subject of study, in order to obtain
a "control" showing the extent to which fried fish eating obtained in the affected area. Thus in
Southwark, in 1900, it was found that 58 per cent. of the population had eaten fried fish within a
month of the time of the enquiry. Again, when, in 1908, question arose as to the prevalence of typhoid
fever in Bethnal Green, a number of streets comprised within the area then involved (and, as it happens,
also within the special area involved this year) were sampled in a similar way. It was found (See
Appendix I., Annual Report for 1908) that 63 per cent. of the control population had consumed fried
fish within a corresponding period just preceding the time of the enquiry. It must be borne in
mind that in both the Southwark and Bethnal Green areas an exceptionally large amount of fried fish
is eaten. In any area taken at random in London, a far smaller percentage of fried fish eaters would
probably be found. As has been shown (Appendix I., Annual Report 1903) typhoid fever in London
mainly occurs in a class of the population among whom fried fish eating is particularly common.
In the prevalence of 1910, in the Bethnal Green area, fried fish alone was in question. This
circumstance greatly simplified study of the relation of fish-eating to typhoid prevalence. Out of
the total 50 sufferers only 32 could have been expected, as a matter of chance, to give a history of eating
fried fish ; but, as a fact (excluding the wrongly diagnosed case) all the sufferers gave such a history.
Of course in localities in which wet fish comes in question the matter is more complicated, for many
persons who never consume fried fish may clearly, be expected to give a history of eating wet fish. It
should, however, be noted that the sufferers in the present outbreak, whether fried fish eaters or not,
had all consumed fish of a particular kind (plaice, flounders, or dabs), but of this more must be said
in the sequel.
Analysis of the history as to fish eating of the sufferers in the outbreak, leads, therefore, to the
grouping of the London cases topographically into 31 clusters or groups, and in their time relations into
two main divisions as already mentioned. The 31 clusters centre around 24 shops or stalls and 7
market streets in which presumably a single shop or stall was at fault, but such shop or stall cannot be
more precisely indicated. In addition to the 31 London groups, there are those in Tottenham and
Edmonton; furthermore, some scattered groups of cases occurred in Bermondsey, Lewisham, Battersea
and Acton (vide infra).
It was clearly important to ascertain whether the 31 London retail supplies which thus fell under
suspicion were in any way associated one with another. Were they in fact derived from common
wholesale sources ? It was ascertained that in every instance the retail supply was obtained direct
from Billingsgate, and in all instances in which information with reference to this point could be obtained,
the fish falling under suspicion was "plaice" (including "flounders" and "dabs"), and was, moreover,
what is known as " late steamer fish." This exclusive derivation from Billingsgate is not, at first
sight, remarkable; but having in view the fact that quite a considerable percentage of the small retail
shops have fish sent direct from the coast by rail, it is a priori exceedingly unlikely that among
31 retail vendors questioned, no single one would be so supplied. As regards the Billingsgate fish,
roughly two-thirds is "rail," and one-third "steamer fish"; and though the category "late
steamer fish" (f) is one difficult to define precisely, it may certainly be assumed that considerably less
(e) It will be noted that whether the fish was sold wet or cooked it had been derived, in the case of each
group of sufferers, from one source.
(f) The fish sold between, say, 9 and 10 a.m., after the higher-priced fish has been disposed of, would appear
to be that referred to.