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In any effort to form from the foregoing an estimate of the increase in diphtheria which may
properly be attributed to school-attendance, the following should be borne in mind—
1. There is suggestion of some transference of scarlet fever to diphtheria which would
tend to exaggerate the increased incidence of diphtheria mortality on the school age.
2. Any increase of mortality at other ages than school age, due to infection of persons
by those who have contracted disease in school, would tend to obscure the effect of schoolattendance
on the school age.
3. It must not be assumed that a holiday in all other times of the year would produce
results identical with those of August, seeing that at that time the seasonal curve is rising to
the autumnal maximum, and this increase may depend upon the disease possessing a greater
personal infectivity at that time than at others.
Report of the medical officer of the London School Board.
I propose now to refer to the report of Dr. W. R. Smith, the medical officer of the London
School Board, published in April, 1896, in which he expresses the opinion "that school influence, as
such, plays but an unimportant part in the enormous increase of the disease during recent years in
London."
The earlier pages are in the main introductory and need no comment. Part I., which follows
these introductory pages, gives account of the geographical distribution of diphtheria, scarlet fever and
measles, and the conclusions of the writer are stated in the last two paragraphs of this part, which are
as follows—
**** although the spread of every infectious disease must necessarily bo favoured by bringing
together large numbers of those most liable to it, yet the conditions most favourable to the diffusion of
measles and scarlet fever are not those most favourable to the diifusion of diphtheria. In other words,
if we wish to explain why Sussex is comparatively free from measles and scarlet fever, but suffers from
excessive diphtheria mortality, while Staffordshire is comparatively free from diphtheria but suffers
excessively from measles and scarlet fever, we must look for some conditions which are not common to
the two counties.
It may be suggested that such a condition is found in the fact that Sussex is much nearer to London
than is Staffordshire; but this suggestion fails entirely to meet the case, since the special liability of
Sussex to diphtheria began several years before that of London. If school infection is the chief cause of
the mortality from diphtheria in Sussex, why should Staffordshire escape? And if school infection is
the chief factor in the spread of measles and scarlet fever in Staffordshire, why should Sussex eseape?
It is evident that several agencies must be at work in spreading zymotic diseases among children, and
it may be taken as highly probable that school infection is one of those agencies. But the comparison
of the geographical distributions of three of these diseases strongly suggests that some local causes
other than school attendance have a more potent influence in selecting the disease and promoting its
diffusion.
I see no reason to take exception to these statements, but would add that, apart from local
conditions to which Dr. Smith refers, variation in the quality of the virus is probably the largest factor
governing prevalence of diphtheria.
In Part II. Dr. Smith publishes a table showing in successive years the proportions in
London of the population at school ages attending elementary schools, and he then states his
conclusions—
It will be seen that while the percentage of children attending elementary schools has largely
increased, viz., from 24.8 per cent. in 1871, to 59.8 per cent. in 1893, the comparative death rate at ages
3-10 has remained throughout these years fairly constant, the lowest proportion having been 312 in 1875,
the highest 369 in 1881, and the average for the 24 years, 347.
There is an obvious fallacy in the method of presenting these facts. It would only be free from
objection if the whole of the diphtheria mortality had been due to school attendance. If the school
attendance has increased since 1871 nearly three times, it could not be expected that the diphtheria
mortality due to other conditions which remain constant, would increase in the same proportion, but
only that there should be some conspicuous increase in that amount of the total diphtheria at school
age which is due to schools.
Apart from this, the statement that "the comparative death rate at ages 3-10 has remained
throughout these years fairly constant," is inaccurate, whether judged by the figures supplied by
diphtheria or by diphtheria and croup, thus—
Period.
Death-rate, ages 3—10. All ages taken
as 100.
Diphtheria.
Diphtheria and croup.
1871-5 323 274
1876-80 345 296
1881-5 352 314
1886-90 357 332
1891-5 358 349
It may also be pointed out that the extent of the increase is obscured by taking "all ages" as
a basis of comparison seeing that the deaths at ages 3-10 form so large a proportion of the deaths at