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91
The number of schools specially affected and visited by the Council's medical
officers during the year was 137, entailing 224 departmental investigations at the
schools concerned. The number of children inspected at these investigations was
26,440 (12,283 boys and 14,157 girls).
In previous reports this relationship has been exhibited in diagrammatic form. Relationship between flea
A chart giving the figures up-to-date appears on the preceding page. The length of prevalence
the base of each shaded area represents the interval of time between the maximum and scarlet
point of flea prevalence and the maximum point of scarlet fever prevalence in each 'ever.
year. With only three exceptions, viz., in the years 1909, 1922 and 1923, the
maximum point on the flea curve precedes by some weeks (from 1 to 10) the
maximum point on the scarlet fever curve. The three years, which have been described
as exceptional, are not really exceptional though technically so classed.
Thus in 1909 there was a mild outbreak in June, preceding the normal autumnal
prevalence, and this quite unusual occurrence cannot be regarded as having any
relationship with the development of the ordinary seasonal wave of scarlet fever,
which followed a few weeks after the maximum of the flea curve (as shown on the
diagram.) Again, in both 1922 and 1923 the autumnal rises in the flea curve were
barely apparent, and the autumnal rises in the scarlet fever curves were only very
slightly marked ; under such circumstances compliance with the general rule that the
first named maxima should precede by a few weeks the two latter maxima was not to
be anticipated. In the Annual Report for 1917 (p. 37) ten lines of argument were
outlined in favour of the thesis that scarlet fever is transmitted by the flea; the
first of these was to the effect that "There is a very close correspondence in form
between the last nine seasonal curves of scarlet fever and of flea prevalence, and
the autumnal maximum of the latter has invariably antedated that of the former,
the antedating being by periods of from 1 to 8 or more weeks." The extended
experience of the years subsequent to 1917 broadly confirms the argument put
forward seven years ago.
A criticism of the flea hypothesis of causation of scarlet fever, which has emerged
since 1920, has been to the effect that in 1920 and 1921 considerable autumnal
prevalences of scarlet fever were recorded, despite generally speaking a downward
trend exhibited in the curves showing prevalence of fleas. In the Annual Reports
for 1921 (Vol. III., pp. 44-7) and 1922 (Vol. III., pp. 80) it was pointed out that
other factors besides the extent of flea prevalence were of course concerned ; for
example, accumulation of susceptible children, and in this connection variations in
the birth rate have influence; and again meteorological conditions need to be
reckoned with, for dry years favour scarlet fever prevalence; moreover, the question
of influence exerted by extent of hospital isolation must not be lost sight of. The
annexed chart brings out very clearly the remarkable diminution, which has occurred
since the records were first started, in the extent of flea prevalence among London
children. This diminution, taken in conjunction with the almost equally remarkable
reduction in prevalence of other vermin (lice and bugs), shows that very remarkable
improvement as regards verminous conditions has been effected in the last 15 or 20
years.
The number of cases of diphtheria in the schools was 3,985 as compared with Diphtheria.
5,641 (1922), 6,661 (1921) and 5,681 (1920). The distribution of the disease conformed
generally to that of scarlet fever, the north-eastern and eastern, with the southeastern
and south-western districts (immediately south of the river in both cases)
being mainly affected. During the year 164 investigations were conducted by
assistant medical officers in 102 schools, and 16,856 children (8,520 boys and 8,336
girls) were inspected. The bacteriological examinations made in the department
in connection with diphtheria numbered 3,000 of which 252 showed the presence
of diphtheria bacilli, whilst 129 raised some suspicion and were referred for further
examination. The remainder were negative.