View report page

127
Report of the County Medical Officer—Education.
1914. From that point the incidence gradually fell until it was reduced to the level prevailing
at the end of 1913. The disease was mild in character and the mortality remained low tl.ro ighout
the two \ears. The number of schools under observation for scarlet fever was 784, and 236 schools
were visited by assistant medical officers for the purpose of investigating the outbreaks.
The persistence of infection of scarlet fever in individual schools.—As time goes on it is becoming
increasingly realised that, from the point of view of prevention, but little can be accomplished by a direct
attack upon the micro-organisms associated with some infectious diseases, and that consideration in this
regard must be directed not merely to bacteriological inquiry but to all the branches of study
concerned in the aetiology of these diseases. In no instance, perhaps, is this more clearly recognised
than in the case of scarlet fever, inasmuch as there has been an uudoubted tendency during the last
ten years for less significance lo be attached to the part played, by the organisms encountered in the
throa', in originating this disease ; it has, indeed, become more and more apparent that in addition to
the susceptible individual and the germ or germs (the x and v, as Pettenkofer termed them), there lies
hidden in the background an unknown quantity (z) having important influence in the production of
scarlct fever.
Some of the reasons for entertaining this belief were summarised six years ago.* First, there
is the inability of the supposed causal organisms to produce scarlet fever. Second, there is the
tendency of scarlet fever to cling to particular premises, and more especially to school classrooms ; the
inadequacy of the theory of infective human carriers, which has usually been invoked, to account fully
for the phenomena observed, may be inferred from the fact that risk of infection can apparently be
obviated when the environment is changed, for example, from the home or school to the isolation hospital
ward. Third, there is the response to variations of temperature, and temperature cannot " get at the
organisms within the body where the temperatures are notab.y high and constant." Finally, some
unknown s is clearly needed to account for the epidemiologv of scarlet fever; its seasonal distribution,
its relation to hot years and to years of deficient rainfall; its historical, geographical and racial
distribution ; and all these things the healthy carrier hypothesis fails to elucidate.
It was tentatively suggested, in 190*5 (see above), that a flet hvp (thesis of causation of scarlet
fever was deserving of examin ition. This su» restion was originally prompted by study of the seasonal
curve of flies, aud more particularly by the difficulties presented by the titre relations of the curve of
fly prevalence and the curves of diseases which the flv has been supposed to transmit. In 1909 a
first flea curve was obtained, and it then transpired that the seasonal prevalence of scarlet fever and
diphtheria lagged somewhat (three or four weeks) behind that of maximum flea prevalence. It has
been pointed outf that " in the case of flies and diarrhoea no such interval is as a rule observed, the
curves are practically superimposed one upon another." This peculiarity is a source of some diffijulty
as regards flies and diarrhoea, but no similar objection presents itself in the case of fl°as and scarlet
fever. Note was further specially made at this time of the marked tendency of scarlet fever to cling
to particular classrooms, and reference was made to the phenomena of " return cases" as justifying
further examination of a flea hypothesis in relation to scarlet fever causation.
In the Annual Report for 1911 (p. 63) more extended reference was made to the same subject
and the curves of three years were then available, for study of the time relations of the seasonal
curves of fleas and scarlet fever. In each year there was found to be an interval (varying from three
to eight weeks) between the maximum for fleas and that for scarlet fever. Attention was no.v more
especially directed to the clinging of infection of scirlet fever to particular schools, and the
observations made from ten to fifteen years ago, by Dr. Niven in Manchister, were found to be
strikingly corroborated by inquiry in the L^nlon schools. The first results of this stu ly were
exhioited in a chart facing p. 134 of the Annual Report for 1912. An unexpected outcomi of this
investigation was that it was realised that some of the schools specially attacked by scarlet fever were
schools not attended by children of the poorest class (to this question further reference will be male
shortly).
A summary of the observations with regard to time relationship of the flea curves and scarlet
fever curves may here be presented. The figures giving the extent to which children in elementarv
schools exhibit evidence of being flea marked are now forthcoming for a period of two years, and
these, together with the records for the preceding four years relating to beds in common lodging
houses, supply a six years' record for study.
The curves which represent the seasonal prevalence for the six years are shown on the accompanying
diagram (D), and it will be seen that the maximum of the curve relating to fleas precedes in each
year, by a period of from some three to eight weeks, the maximum of the curve relating to scarlet fever.
The precise interval separating the maxima of the curves is indicated by the width of the
shaded area as shown in the diagram for each of the years under review. The method of counting
from maximum to maximum is only a rjugh one, and somewhat different intervals would be recorded
if the respective curves were "smoothed." Ttie "flea" curve for the year 1912 exhibits two
maxima, and the interval between the earlier maximum and the maximum of the corresponding
scarlet fever curve, indicated by the shaded area, is eleveu weeks. If the later maximum of the flea
curve be taken, the interval is reduced to five weeks. Broadly, however, it is clear that there is a
substantial lag (of some three or four weeks, or more) between the maxima in the flea curves and in the scarlet
fever curves.
During the past year enquiry has been instituted into the extent to which scarlet fever on the
one hand and flea marks on the other hand prevail ;n particular schools. Selection, has been made of
some 50 schools which may be classed from the point of view of flea prevalence, as "good" schools
and some -50 others, which may be classed as " bad " schools. The, at first sight, anomalous result is
obtained that children in schools which are "good," when regarded from tbe point of view of flea
* Trans. Roy. Soc. Med., Vol. II., p. 83, 1908.
+ (Annual Report of Medical Officer of Health, 1909.)