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incidence was about equal on males and females at these ages in the years just before
the War; in 1917 and 1918 (at the time when the greatest number of men were
abroad) the "males attacked per 100 females "fell to 46 and 49 respectively; the
percentages of males then gradually rose in fair correspondence with the additions to
the males (owing to return of survivors) to 53, 60, 70 and 70 in the four succeeding
years. In the small numbers attacked during the last two years this percentage has
shown a decline but, while this is a curious phenomenon demanding further study,
it is difficult to associate it with protective inoculation.
The last two years have brought, in England and Wales, (as well as in London) a
small increase in notified cases, and localised outbreaks of typhoid or paratyphoid
fever have occurred. It is noteworthy that in certain of these outbreaks, contaminated
foodstuffs, deemed to have been infected by bacillus carriers, have been
held to be at fault. It is particularly instructive, in this connection, to find from
a recent issue of the American Journal already referred to (December 12th, 1925),
that "in many parts of Europe, the 1924 typhoid rate was notably higher than that
for 1923," and in a still later issue (March 27th, 1926, pp. 948 and 955) to note that
there has been observable in the large cities of the United States, in 1925, a
"substantial and widespread increase in typhoid." There does not, it is stated,
"appear to have been any extensive prevalence of water-borne disease, and barring
the oyster infection early in the year, no particular multiplication of sources of
infection seems to have occurred. It is tempting to relate excessive typhoid
prevalence over a wide territory to some general factor, such as weather conditions,
but it will be necessary to collect more data before this aspect of the problem can
be profitably approached. In the meantime, the annual fluctuations brought out
in these summaries will suggest to epidemiologists various lines of enquiry."
It is difficult to resist this invitation to speculate on a "typhoid trend," which
has produced somewhat similar statistical results in both hemispheres. Two guesses
as to possible world-wide operative causes, which may have exercised some influence,
may perhaps be hazarded. First, there is an undoubted tendency, nowadays, todiagnose
typhoid fever, or paratyphoid fever, largely on Widal reactions ; and often
even at that, on reactions observed in (what used to be considered) comparatively
low dilutions. Secondly, here in England, at any rate, there seems to be a tendency
of late years, to overlook the existence of localised prevalences of gastro-intestinal
influenza ; and it would be interesting to learn if, in any outbreaks of this last-named
disease which may have chanced to be recognised, Widal reactions were found in
dilutions as high as say 1 in 40 or 1 in 50 ; bearing in mind, of course, the fact that
it used to be understood that normally a serum may react in such a low dilution
without necessarily justifying a diagnosis of typhoid or paratyphoid fever.
In the days before agglutination reactions, it was not uncommon for the question
to be raised prima facie, as to whether a typhoid prevalence might be due to
milk, but for it to be agreed subsequently, in the light of careful statistical
enquiries thereupon instituted, that a milk thesis was not by itself adequate to
explain the whole of the exceptional incidence of the disease. Outbreaks in which
difficulties of this sort arose are referred to in a paper published in 1911 (Trans.
Hoy. Soc. Med., Epidem. Sect., pp. 110, 116 and 145), and an interesting case
of the kind is one which occurred in 1898, and which is discussed very fully in the
Annual Report for 1924 of the Medical Officer of the County of Lanark (pp. 477
et seq.). Furthermore, in this same connection, an important recent paper" On
the prevalence of typhoid carriers in a general population " (Journal of the A.M.A.,
3rd October, 1925, p. 1036) may be referred to. It was found, by the writers
of this paper (Welch, Dehler and Havens, 76th Session of the American Medical
Association, 1925) that, by use of the most approved methods, from 3 to 10 per cent,
of 1,076 dairy employees examined (the higher percentage being found in a locality
where there had been a high typhoid-rate a few years previously) were healthy