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102
Annual Report of the London County Council, 1910.
In striking contrast stand the facts relating to fried fish. Among the total number of cases (79)
in Bethnal Green there were 68 giving a history of having eaten fried fish within a month of the onset
of illness. Limiting consideration to the area of special prevalence, out of 50 cases, all but one had eaten
fried fish obtained in the area; and this last case was subsequently ascertained, at the Metropolitan
Asylums Board Hospital to which the patient was sent, to have been notified in error.
Examination of my notes shows that in all the "multiple house invasions" the sufferers had
partaken of the suspected fish en famille; while, in the large majority of cases in which only one member
of a family suffered, it was found that that member had been in the habit of obtaining a fish dinner
or fish supper away from home. (6). In many of the instances last named it ultimately transpired that
while the fish consumed by other members of the family was from a shop to which no suspicion was
attached, the fish consumed by the sufferer was obtained at one of the shops supplying numerous other
sufferers. Thus cases (28), (37), (48), and (52), are instances in point; the patient had obtained fried
fish from a suspected source, while other members of the household had not eaten this fish.
Examination of a fried fish hypothesis of causation.—With a view to testing further a fried
fish hypothesis, the whole subject of retail fish supplies in the special Bethnal Green area was made
the subject of careful study. In this enquiry, I was fortunate in having the help of Mr. Rowsell, the
Bethnal Green food inspector, who has intimate local knowledge, and who gave me every assistancein
his power (c). Within the special area in Bethnal Green there are 27 fried fish shops. The approximate
extent of trade done by each shop can be roughly estimated; some are quite small, only disposing of
one or two trunks of fish daily; the majority deal on an average with three or four trunks daily; there
are a few shops carrying on a larger trade than this. The question now arises, assuming that 50 fried
fish eaters be selected at random within the special area, and that they be asked to name the fried
fish shops from which they had during the preceding month obtained fried fish, how often might it be
anticipated that each of the 27 fried fish shops in the area would be named ? Regard must obviously
be paid to the extent of the business done at each shop, and to the shop's position in the area; shops
centrally situated in relation to the aggregation of cases are obviously more likely to be named than
those situated on the area's confines. It would, of course, be expected that some of the 50 fried fish
eaters would name more than one shop. As a matter of fact the 50 sufferers gave some 80 names;
of these 71 were those of shops within or close to the area, the others being, as a rule, in the neighbourhood.
Using the information given by Mr. Rowsell, I estimated that if 71 names had to be distributed
among the shops (within or immediately adjoining the area) in the proportions which mere chance would
determine, having regard as aforesaid to the amount of trade done and the position of the shop within
the area, it might be anticipated that:—In one instance a particular shop would be named 5 times.
In 3 instances particular shops would be named 4 times. In 3 instances particular shops would be named
3 times. In 12 instances particular shops would be named twice. In 8 instances particular shops
would be named once. There would then remain 13 names to distribute; these might reasonably
be allotted to shops just outside the area, as obviously some of these shops would be patronised as well
as the shops within the area. Against each shop can now be set the number of times it is, so to
speak, entitled to be named, and the number of times it actually was named, by the sufferers from typhoid
fever.

(b) This was in marked contrast to the facts observed concerning mussels.
(c) The question of the age-incidence of the sufferers was of course considered. Hitherto, in fish outbreaks,
the ages 3-25 had been found to be more especially attacked. The cases in Bethnal Green, at these ages, slightly
exceeded, and in the London prevalences generally such cases considerably exceeded, those at other ages. On the
whole it was found that the ages of the Bethnal Green sufferers corresponded with the ages of the purchasers at the
Bethnal Green shops.
(d) Owing to the nature of the assumptions made and the approximate character of the results, fractions have
been disregarded and a whole number has been placed opposite each shop in this column. Obviously if the data
available had been quite precise the sum of the numbers in columns two and three of the Table would have approximated
more closely to one another. If case 69 be included, shop B was named 13 times, and if two cases at a little
distance from the special area be included, shop 5 was named 27 times. (See Diagram.)