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Infectious diseases.
The accompanying diagram on page 44, giving quarterly variations in death rates in measles
and whooping cough and in notifications in scarlet fever and diphtheria, clearly shows that the years
on the right hand of the diagram compare favourably with those on the left. In measles and whooping
cough more particularly the declining birth rate is no doubt accountable in part for the decline ; this
fall in the birth rate dates from about 1880, but was more marked after 1900. In scarlet fever and
diphtheria the line between the years 1902 and 1903 seems to mark a descent from a higher to a lower
plane of prevalence.
In this later period there was a fairly rapid rise in the average attendance in the schools steadily
maintained between 1900 and 1910; then followed a slight falling off in the succeeding three or four
years, and the war had a marked effect in reducing school attendance. Since 1918 the percentage
of attendance has been rising again towards a more normal level. Ignoring the effect of the war and
making every allowance for the more efficient methods adopted for improving the attendance, it is
significant that increased attention to control of infectious diseases in London schools has synchronised
with a higher standard of school attendance.
In estimating the causes of reduced prevalence of infectious diseases within recent years due
weight must of course be given to hospital isolation and treatment, as also to what may be termed in a
broad sense the public health conscience. It is impossible, however, to resist the impression that the
systematised control of infectious diseases in the schools in recent years has also had marked influence.
It will be noted that although, taken on the whole, the general prevalence of infectious illness
was lower during the period of medical influence, epidemics have occurred from time to time in the later
years, which bear comparison in point of magnitude with some of the earlier epidemics ; but it is noteworthy
that the intervals between these abnormal prevalences have been extended, and it is reasonable
to ascribe this postponement of the "major waves" to the protection of the individual child by the
generally improved measures adopted within recent years.
Rules of procedure for dealing with infectious diseases appear in 1885 in the School Management
Code of the London School Board, and these were added to from time to time. On 12th March, 1891,
the first mention is made of a form for notifying exclusions to the local medical officer of health and the
superintendent of visitors. The Code for the same year refers to notification procedure under the
Act of 1889 and the Public Health London Act, 1891. The Code of 1902 for the first time refers to " form
84" being sent by the teacher to (a) the medical officer of the board, (b) the divisional superintendent,
and (c) the medical officer of health of the district. In 1904 the Council became education authority
and the present procedure was gradually evolved, under which schools or departments are very rarely
closed, but reliance is placed upon exclusion of particular scholars (actual sufferers) and upon a carefully
regulated scheme of exclusion of susceptible contacts usually only from the same family, but in some
cases also from the same house.
Scarlet fever.
The high incidence of scarlet fever which marked the closing months of 1920 was maintained
and even intensified in 1921, the total cases notified in the latter year being 32,739. This figure
was exceeded in 1893, but in no other year since notification became compulsory. The observed relationship
between exceptionally dry summers and high scarlet fever prevalence is well exemplified in the
records of 1921, and the high incidence in the latter half of that year may in part perhaps be ascribed
to the extraordinary deficiency of rain. Judging, however, from past experience the recent prolonged
incidence of scarlet fever will be followed by a period of diminished prevalence, mainly for the reason that
immunity is conferred by attack and that, consequently, after a wide-spread and prolonged epidemic, the
population contains a relatively small proportion of susceptible units.
During the past twenty years there have been three great prevalences of scarlet fever in London,
separated by intervals of approximately seven years. These major waves are also evident in the curves
for the constituent boroughs of London, but there are intercurrent and quite localised prevalences.
When these are severe the succeeding major wave is proportionately less severe in the locality of these
outbreaks. If it may be assumed that the margin of susceptible units at any given time is a definite
quantity and easily depleted, it would appear that the occurrence of these local and transient outbreaks
is not readily reconcilable with an hypothesis that direct spread from child to child (by the breath or by
epithelial scales or mucous discharges) is the sole cause of the major waves of scarlet fever prevalence.
The exceptional character of the meteorological records lends particular significance to observations
on the prevalence of fleas in school children and in common lodging house inmates. The conditions
favouring the propagation of fleas have been examined in various laboratories, and it has been demonstrated
that the flea at all stages in its life history is sensitive to relatively small deviations from an
average degree of humidity and temperature. In 1911 and 1914 the summer rainfall was much below
the average and the temperature high, and in both years there was a rapid fall in the latter half of the
year in the recorded prevalence of fleas: the conditions were repeated with much the same results in
1921. On the other hand, in 1916-17 there was a marked fall in flea prevalence which cannot be accounted
for in the same way. It will be seen from the diagram (p. 46) that in each of the years 1909-21, the
flea maximum antedated the scarlet fever maximum by from one to as many as thirteen weeks, the
intervals being shown by the hatched areas; the diagram further shows a general downward trend in
the records of flea-marked children. Apart from special steps taken to cleanse verminous children there
has undoubtedly been of late years an increase in the parents' concern generally with regard to the
harmfulness of parasitic insects. The conclusions drawn from previous study of the flea question were
summarised in the annual report for 1917 (p. 37), when nine years' records of flea prevalence were
available; and in the report for 1918 (p. 47), the incidence of epidemic throat maladies in the metropolitan
boroughs over a series of years was examined.
The criticism has been made, that on the flea hypothesis there should have been higher autumnal
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