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ment of water supplies, and, following upon that, improvement of shellfish and fish supplies, have been
the cause of the great decline of typhoid fever. It seems probable that the two (water and food) stand in
close relation one with the other and this may be true also in respect of the causation of Asiatic cholera ;
if so, explanation of these facts must almost necessarily be sought in the direction of search for some lowly
form of life which finds opportunity for development in sewage polluted wells and streams and sewage
polluted foreshores and opportunities for spread by shellfish, and by fish which have fed upon shellfish.
On such a view question seriously arises as to whether Eberth's bacillus forms a necessary link in the
chain of causation of typhoid, or whether it must not be degraded to the rank of a mere associated
organism. There remain, however, on the above hypothesis two difficulties. First, the frequent association,
in war and in asylums and prisons, and even in ordinary civil life under conditions of neglect
of sanitation, of dysentery with "typhoid fever"; and when this combination is present it has been
as a rule held that direct spread of infection from case to case must play a part in favouring dissemination
of disease. The "typhoid" seen under such conditions may perhaps differ from the epidemiological,
though not markedly, from the clinical, point of view, from water typhoid or typhoid traced to
fish or shellfish. An explanation of this which may be suggested is that, epidemiologically considered,
there may be two typhoids and not one typhoid. Clinically, the resemblance may be as close as the
resemblance say of typhoid to paratyphoid, or of certain cases of typhoid to typhus fever. If, however,
following in Sir William Jenner's footsteps, the clinical test, the study of a particular symptom group,
be regarded as of minor importance, and attention be concentrated upon aetiology, it seems clear that
the typhoid, at any rate, of London (apart perhaps from some of its institution "typhoid") differs
markedly from the "typhoid" plus dysentery of Gallipoli, or of the South African or Spanish American
wa-s. This conclusion seems forced upon the mind when comparison is made on the one hand between
cases of typhoid widely scattered over London, all linked together by the fact that they yield a history
of consumption of cockles or oysters coming from a particular source, and all agreeing in this, that no
secondary ca es follow in their wake; and on the other hand a group of cases in a mental or fever hospital,
extending it may be over some months, showing possibly a tendency to be limited for a time to the
male or female side or even to particular wards, and sometimes occurring coincidentally with marked
prevalence of dysentery in the same institution.
The phenomena of institution outbreaks of typhoid may be contrasted with the behaviour of
typhoid in London as a whole. As a rule, in them, water and shellfish causation can be definitely excluded.
The question of fish presents more difficulty. In a hospital outbreak within my experience, I found
strong reason for concluding that fish was at fault. Again, one of my colleagues discovered in the course
of inquiries made at another institution that the husband of one of the inmates only agreed to his wife's
remaining there on the condition that she should not be given any fish; when questioned as to his
reason for making this stipulation, he explained that" he was in the trade himself." In some of these
institution outbreaks arrest of spread of "typhoid" has followed, upon close attention being given
to methods of dealing with foul linen, and on use by nurses of antiseptic precautions, and in some instances
it has been claimed that protective inoculation has proved of service.
The second difficulty is the spread of typhoid fever by milk. In the early days infection of the
milk was attributed to the use of polluted water for washing cans, and by some observers to a disease
of the cow. Later the intermediation of healthy carriers has been invoked. A recent writer on the carrier
question shares the doubts of many sceptics with regard to "Typhoid Mary," but considers the case
of the "Folkestone carrier" a convincing one. My own view is that in neither of these classical instances
was the case proven. (Proc. Roy. Soc. Med. Vol. IV., EpidemSect., pp. 109and 115.). Thesubjectof milk
typhoid seems in fact to be still obscure. Here, again, the suggestion may be made that perhaps, epidemiologically
considered, this form of typhoid may not be quite identical with water and fish and shellfish typhoid.
It is possible that just as "neuritis" may be due to diphtheria or lead or alcohol; or "scarlet 'ever"
may be "surgical," or "puerperal," or milk borne, or flea transmitted; so the typhoid symptom group
may be produced by more than one cause. The bacteriologist claims that this is so from his standpoint;
why should not the field worker make a similar claim from the epidemiological point of view?
Is it possible, that, just as" in modern bacteriological theories of disease we may have concentrated
attention too exclusively upon particular links in the chain of parasitism orgetting
that a particular parasite may be merely one of a series, and that it may in some cases be replaced in
that series by another parasite" so in epidemiological theory we are apt to fail to recognise that
symptom complexes may result from the action of more agencies than one, each of them competent to
set in motion the required sequence of events and thus to serve as a link in the chain of causation
in question.
Tuberculosis.
The deaths from pulmonary tuberculosis in the civil population of London during 1919, numbered
5,332, a decrease of 1,716 from the previous year. The corresponding figures for 1916 and 1917 were
6,491 and 6,908 respectively.
Tuberculosis other than phthisis, caused 992 deaths in 1919 as against 1,575 in 1917 and 1,398
in 1918.
The decrease in mortality among children under five years of age noted in previous years was
maintained in 1919.
The number of " primary " cases of tuberculosis notified in London during 1919 (53 weeks)
was 15,587, the corresponding figures for the years 1915-18 being 18,661, 17,631, 18,735 and 19,178
respectively. These figures do not relate exclusively to the civil population. Of the total " primary"
cases of tuberculosis notified in 1919, 12,356 were pulmonary, and 3,231 were other forms of tuberculosis.