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all ages. The increase is better shown by taking as a basis of comparison the death rate at all ages
exclusive of ages 3-10, the following figures are thus obtained—
Period.
Death-rate ages 3—10. All ages exclusive
of 3—10 taken as 100.
Diphtheria.
Diphtheria and croup.
1871-5 549 407
1876-80 646 469
1881-5 665 526
1886-90 673 580
1891-5 675 638
The next few pages of Dr. Smith's report are occupied by tables showing that some districts in
London have suffered from diphtheria in greater degree than others, but no inference appears to have
been drawn from this fact.
Following these tables is a statement of the number of children at each year of life attending
the London School Board schools, and objection is taken to my inclusion of children between three and
four years of age among those of school age. The small number of children at this age attending
these schools leads Dr. Smith to state that "it is more correct to speak of four years instead
of three years as the age at which school attendance commences. We should therefore expect that
any tendency to school infection would show itself in a marked manner at age four." By comparing
diphtheria in 1881-90 with diphtheria in 1871-80 he shows that the greatest increase in London is
in the second year and in England in the third year of life, which is obviously earlier than school age.
I think there is no doubt that this increase is, in the main, due to transference of croup to diphtheria;
reference to Tables I. and II. relating to diphtheria and croup shows that when these two diseases are
considered together the increase at this age is less than at ages 3—, 4—, 5—, and 10—.
The question whether children of the age 3— can properly be included among children of school
age is not of importance. I included this age because as the result of inquiry I made, I satisfied myself
that in schools other than board schools there are a sufficient number of children at this age to make
the course I have adopted desirable. Such inclusion, of course, leads to understatement of the
increase of incidence on the school age, as will be apparent by reference to Tables I., II. and III.
The next two pages of Dr. Smith's report are devoted to showing that girls from 5-10 are
more liable to die from diphtheria than boys of this age. It is urged that "no difference in the school
conditions of the two sexes can be imagined which would yield even a plausible explanation." The
question does not need consideration here; it has before been explained by Dr. Downes on the ground of
the greater domesticity of girls. Pages 17, 18, 19 and 20 of Dr. Smiths' report are devoted to discussing
the age incidence of attacks of diphtheria. He publishes diagrams showing that the ages which are
most affected by diphtheria are not the ages at which there is the largest school attendance,
and he states from the teaching of these diagrams that "it is impossible to resist the conclusion
that no special increase of liability to diphtheria can be traced to the beginning of school attendance."
It is obvious that no lesson is to be learnt from these diagrams beyond the well-recognised fact
that there is a natural inequality of age incidence of diphtheria. Whether, and to what extent,
this natural age incidence has been modified by school attendance can only be shown by comparing
the age incidence of attack in two populations, the one attending school, the other not attending
school, or of one population during periods of attendance at school, and periods when school is not
attended, or when school attendance is less.
On page 21 of Dr. Smith's report is a discussion of diagrams representing the number of notified
cases of diphtheria in each week in relation to the mean of the year, and similar to those I have published
in my annual reports, except that Dr. Smith's diagrams only exhibit the effect of the August holiday
on all ages. Perhaps for this reason the relation between decrease in prevalence in August, so marked
among children of school age, is less obvious to him than to myself. He publishes, however, a table
representing the number of notified cases at each age during three successive periods of four weeks in
1895, and comments on the fact that the decrease in the second period, when the influence of the
holiday would be manifested, is almost as marked among children below school ages as at school ages.
Neither his figures nor mine support this contention. He omits, also, to point out that diphtheria
among the younger children declines, and subsequently rises, a week later than among the older
children, suggesting, as I have before said, that a number of the younger children receive their
infection from the older children.
On pages 22 and 23 of his report he shows the number of cases of diphtheria notified in
each London district in each week of July, August, and September of 1895, and he states that—
The various sanitary areas show a marked divergence in the incidence of the disease, before,
during, and after the school holidays. School influences should be the same in all of them; but we find
that in the crowded eastern and southern districts, with the exception of Greenwich, the school holidays
practically did not affect the prevalence of diphtheria. Only in the west and northern districts is the
marked fall followed by the equally marked rise noticeable.
So far as these remarks are based on the figures of particular districts it must be recollected
that the figures are small and therefore less reliable, and the important fact has to be borne in mind
that diphtheria may at one time be spreading in a school or schools in a district and not at another.
It is only by taking the figures of a large population or groups of districts that the general effect of
schools can in this manner be studied. The following table shows the figures relating to groups