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the effect of the introduction of national insurance in bringing the practitioner into closer relation with
the homes of the poor.
The divergence of the calculated from the actual deaths from summer diarrhoea is not the
only change which has occurred in recent years. There is an interesting point with regard to the time
relations of the curve of summer temperature and that of diarrhœal deaths. to which attention was particularly
directed recently by Dr. John Brownlee. The relationship of the two curves can best be studied
in years in which the temperature has risen sharply well above the normal, and then fallen so as to
give a well-defined peak to the curve, as in the years 1881,1886,1896-7,1904-5, and 1911. In the more
recent similar years, 1916, 1919 and 1921, while the relationship as to contour is still fairly maintained
it is remarkable that the peak of the mortality curve instead of lagging behind that of the temperature
curve by a fortnight or so, is actually as much as from seven to eight weeks later. In 1842 and 1852 both
years with extreme summer temperature, the lag was about one week; 1911 was, however, hotter than
either of those years yet there was a lag of about three weeks, so the amount of lag does not depend
entirely upon the excess of temperature, although it is noticed that in a series of proximate years the
lag tends to be shorter in those with excessive temperature. At the foot of the diagram (p. 9) approximate
curves are shown representing the actual summer deaths and the number estimated from
the temperature readings in three successive ten year periods ended 1920. The increase in the lag
of the mortality curve appears to have commenced after 1900, and it was about this time that the
marked decline of infantile mortality generally commenced. When the deaths from all causes other
than diarrhœa during successive summers since 1876 are examined it is found that after remaining
constant for twenty-five years 1876-1900, the mortality falls down to the present time. The change
cannot be due to differences of classification, since the diarrhœa mortality also falls, nor can administrative
measures for promoting infant welfare come into account so far back. There can be no doubt,
however, that during the closing years of the last century a steadily increasing amount of attention
was directed to infant mortality, and it was also about this period that the critical movement of population
north of the Thames began to assume considerable proportions thus lessening overcrowding in certain
poorer localities, Thus infants born after 1900 seem to have been rendered more resistant, and in
correspondence with this there was improvement in the death-rate at parental ages. Herein lies
perhaps the explanation of the gradually increasing lag of summer diarrhceal mortality upon the temperature
excess, namely increased power to withstand the strain of abnormal conditions. The late
Dr. G. B. Longstaff was disposed to insist upon the effect of hot weather upon the nervous system plus
the influence of "products of putrefaction which are dependent upon prolonged high temperature";
the lag of the mortality after the summer temperature does not seem consistent with the hypothesis of
perverted nervous influence alone, though there is the possibility that the strain caused by bodily adjustment
to abnormal temperature may open the way to zymotic processes in the intestines resulting perhaps
eventually in development of so-called specific organisms. At any rate the similarity of contour of
the temperature curve and that of the diarrhœal mortality, maintained in spite of the lag being increased
from two to as much as eight weeks, shows that the temperature is the fundamental factor; with the
increase in lag the fatality of diarrhœa has diminished, and both circumstances appear to be due
to improved physical conditions.
A possible explanation of the decrease in summer diarrhœa mortality in recent years is the
replacement of horse traction by mechanical traction, and the resulting decrease in the amount of horse
manure. The relationship between summer diarrhœa, and fly prevalence, both generally and in selected
areas in the neighbourhood of stables, is discussed in the report for 1907 (Appendix II. Report on
Nuisance from Flies, pp. 8-9).
During 1921 (52 weeks), there were 329 cases of typhoid fever notified in London, as compared
with 387 in 1920. The deaths numbered 60, as against 48 in 1920. Of the total cases notified, 193
were admitted to the hospitals of the Metropolitan Asylums Board, of these it was found that 82 or 42.5
per cent. were not typhoid fever. Of the 60 deaths occurring among Londoners 14 were inmates of
County asylums outside the county boundary, and as the cases occurring in these institutions are not
notifiable in London the deaths comparable with the notifications become reduced to 46.
Typhoid
fever.
In 19 instances more than one case was notified in the same house. In Kensington six cases
occurred in one house, in Stepney and Poplar four cases; in St. Pancras (twice), Chelsea, Wandsworth
and Finsbury three cases; and in the eleven remaining instances there were two cases. In the Kensington
group one of the cases proved fatal; the source of infection was not established. The four
cases in a Poplar house were all children of one family of ages from 7 to 15 years; the first
case was thought to have arisen from river bathing, and the other three were considered to
have been infected by this case. In respect of the household of four attacked in Stepney,
no information could be obtained as to the possible source of the first case; the time
relation of the onset in the other three cases was held to be suggestive of infection by the original
case. In one of the St. Pancras houses in which three cases occurred the question of possible infection
by a carrier, a cook employed by the family was considered; it was, however, not possible to complete
the investigation. In the other St. Pancras household with three cases, fish obtained from a barrow
is mentioned as a possible source, but there is also the possibility that an illness which preceded the three
notified cases was typhoid, although not recognised as such at the time. Nothing was elicited to account
for the three cases (two nurses and a maid) in one house in Wandsworth. In the Chelsea instance
of three cases in a family the information points to the disease having been acquired while away from
London; in Finsbury, where three children of school age were simultaneously attacked, wet fish is
mentioned as the possible source of infection.
In the 50 cases in respect of which confirmatory bacteriological results were obtained, the presence
of B. Typhosus was shown in 7 cases; 25 were described as "Paratyphoid"; while 6 were described
as Paratyphoid A and 12 as Paratyphoid B.
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