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19
The accompanying Diagram, showing incidence of typhoid fever, during the
13 four-weekly periods in each year, has been prepared to exhibit its behaviour
in the 27 London sanitary areas during the past 32 years. (In order to facilitate
comparisons Stoke Newington has been combined with Hackney, and Deptford
with Greenwich, as the separation between these two pairs of boroughs could not
readily be effected in the earlier years under review).
Review of
typhoid fever
in London
during the
last 32 years.
As a preliminary to the study of this Diagram, brief reference should be made
to the incidence of the disease when a longer period than 32 years is passed under
review. The diagram on p. 11 of the Annual Report for 1919 gives a general idea
of typhoid fever incidence in London as exhibited by available mortality statistics;
the accompanying diagram, on the other hand, is based upon notification statistics,
and thus relates necessarily to a shorter series of years. The mortality figures
are forthcoming since 1869, as in that year typhoid fever was distinguished from
other "continued fevers"; and from 1869 down to 1884, there was no very marked
decline in the typhoid death-rate; in those years, however, doubtless many
cases which were not really typhoid were, owing to difficulty of diagnosis, included
in the returns. In 1885 came a drop to a lower level, which was practically maintained
until 1900. The sudden fall from 1884 to 1885 is almost as marked in the
figures for England and Wales as in the London figures. In 1894 Bulstrode's Oyster
report was published, and in 1900 the first fish outbreak was described. Since
1900, the general trend has been a decline, at first rapid from 1901-05, then came
some slackening in the rate of fall down to 1912, and since that date typhoid fever
has been at quite a low ebb.
The whole range of mortality statistics, 54 years, may thus be divided into
three periods—a very high death-rate for 16 years (up to 1885); during this period,
however, the deaths registered from "typhoid fever" probably included some
typhus fever, cerebrospinal fever, appendicitis and other general and abdominal
diseases: a lower level for a further period of years (up to 1901): then a steep
decline for a few years to the present low rate, which has practically been maintained
without any noteworthy fluctuations.
Turning now to notified cases shown in the accompanying Diagram.
(1). The first lessons to be learnt from the Diagram are that during the past
20 years typhoid has greatly declined, and that the "normal" autumnal increase
of prevalence which became only slight in 1907, was absent in 1909, and has since
1911 practically disappeared. These changes have affected the whole of the boroughs
of London, and the incidence was much heavier up to 20 years ago on boroughs
containing considerable aggregations of poorer persons (St. Pancras, Islington,
Hackney, Finsbury, Shoreditch, Bethnal Green, Stepney, Poplar and several South
London boroughs); this excessive incidence on these boroughs, has now, after a
sharp decline, ceased to be apparent. Such a transformation can only be due to
the removal of some special source or sources of infection, which up to the end of
the last century had operated widely, and then practically failed to do so in the last
10 or 12 years. During the nineties and in the early years of the twentieth century,
this particular influence must have been one affecting mainly poor populations; and
during the fortyyears 1869-1908 it was especially manifested in the autumn months.
In view of the fact that the waning of this prejudicial influence only became
apparent about 20 years ago and that it did not cease to operate until after 1911,
the falling off can clearly have had little to do with improvements in drainage or
water supply, for both these conditions had been the subject of a great deal of attention
long before the close of the last century, indeed, at least 15 years or more before
the decisive fall came. Again it can have had but little to do with limitation of
direct spread of infection from case to case, for fully 10 years before the close of
the last century, hospital isolation, disinfection, etc., were extensively practised.
It can have had nothing whatever to do with preventive inoculation or with segregation
of " carriers," for these measures have never been applied on any really appre-