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Analysis therefore of the particulars ascertainable concerning typhoid fever prevalences in relation
to consumption of small plaice from the A3 area, indicates:—
(i.) That since 1908 there has been an absence of any considerable localised prevalence
of typhoid fever in London, save on two occasions, in 1910 and 1911. On each of these
occasions, small plaice was incriminated as the cause (see Annual Reports for these years),
and it may be added there are reasons for believing that this fish was brought into London
from the A3 area.
(ii.) That there has, apart from special outbreaks, been observable in London markedly
low prevalence of typhoid and notable flattening out of the autumnal rise in prevalence.
(iii.) That there has been diminution, especially in the last six years, in the amount of small
plaice coming to Billingsgate from the A3 area; first Hull and then Grimsby have altogether
abandoned the A3 "nursery grounds."
It is a matter of some interest, in the light of these facts, to inquire whether there is any differentiation
of type in the typhoid fever curves for different parts of England and Wales, corresponding
to differences as regards fish supply. As noted in last year's report, there are very remarkable correspondences
observable in the outline of the curves for towns situated near one another, and this is
obviously much more easily comprehensible on the ground of their receiving food supplies from a common
source, than on the healthy carrier hypothesis. Instances of such correspondences may be seen on
the annexed chart—e.g., in Southampton and Portsmouth, in Manchester and Salford, in Hull, York,
and Sheffield, and in South Shields and Gateshead.
Diagram I.—Incidence of typhoid fever (1904.1914) in three areas receiving fish from the North
Sea and in the principal towns of England and Wales.
Diagram II.—Similarity of incidence of typhoid fever (1904.1914) in certain neighbouring towns.
(Dotted line shows in each instance the moan of eleven years).
Diagram III.—Relationship of autumnal to annual prevalence in Grimsby, London and Home
Counties and Hull, and in several county areas.
(In this diagram the annual prevalence in 1911 is taken as the unit throughout for purposes of comparison.
The continuous line indicates annual prevalence, and the dotted line indicates autumnal prevalence).