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of the influence exerted by mucous discharges, and Dr. Arnold, who had worked with Dr. Niven in
Manchester, in a paper read before the Epidemiological Society in 1912, conclusively demonstrated"the'paramount importance of housing conditions in relation to the occurrence of return cases"; he showed,
after taking full account of the fact that there are twice as many susceptible persons per house in the
homes of the hospital cases as in the homes from which the patients are not removed to hospital, that
there still remains a big gain in the hospital group during isolation of the case in hospital; and, more
important still, his figures show conclusively that the conditions to which the hospital patients return
are, in comparison with the home.treated cases, very favourable for the production of further infections.
Dr. Seaton's figures, published in his"Infectious Diseases and their Preventive Treatment,"confirm
these conclusions, and his diagrams exhibit the time relations of return cases in home treated and
hospital treated cases in a particularly instructive fashion.
Dr. Shadick Iliggins, when at Birmingham, carefully investigated the question of return cases,
and he read a paper before the Epidemiological Society, in 1913, on the relationship of the presence
of the diphtheria bacillus to persistence of scarlatinal infectiveness. During the latter part of 1915
and in 1916 he very kindly furnished me with particulars concerning all the return cases occurring in
St. Pancras, and study has been made of these in the light of the observations detailed above.
Some fifty possible return cases have come under review; for the most part, in those occurring
after a long interval, the evidence is far from conclusive; consideration has been limited, therefore,
to the 26 return cases affecting children of school age within four weeks of the return of the supposed
infecting ease; they were all elementary school children, and 8 occurred in one, and 7 others in another of
two of the poorest areas in St. Pancras, in which scarlet fever was especially prevalent during the period
under review. In a third notably poor area in the borough the disease was little prevalent, and there
was a corresponding absence of return cases from that area; it should be noted, however, that this
third area had suffered severely from scarlet fever shortly prior to the months to which the present
statistics relate.
It is not possible to give exact figures as to the school populations involved, but roughly they
may be divided into three groups :—
(a) Nearly one.sixth (i.e., some 5,500) of the total number of children at risk belong
to the group which includes children not attending elementary schools; these had far less than
their share of scarlet fever (some 40 cases), and only one was suspected of causing a return case.
(b) More than one.half (i.e., some 18,000) of the elementary school children at risk lived
outside the two especially affected areas; these children yielded some 290 cases of scarlet fever,
and there were 11 return cases.
(c) The two especially affected areas, with rather more than one.third (i.e., 6,000 plus
5,500, or 11,500) of the elementary school children at risk yielded some 270 cases of scarlet fever,
and there were 15 return cases.
Among the schools in (b) two were particularly heavily attacked, and if the figures for these
two be added to those for the schools in (c) the group of schools thus constituted yielded 360 cases and
21 return cases.
It is important to note that in the large majority of the supposed infecting cases neither
desquamation nor mucous discharges were present at the time when the mischief was presumably
caused. It will be seen, therefore, that the predominant influence of home environment, first hinted
at by Mr. Thompson in 1895, and which has been gradually coming more clearly into view as desquamation,
mucous discharges, etc., have receded into the background is very clearly brought out by analysing
the St. Pancras results. The children in the better homes escape lightly both as regards scarlet fever
and as regards return cases; the children in the elementary schools generally suffer in both respects to
a much greater extent; but the children in the two special areas, which include most of the poorest
schools in the borough, have still more pre.eminently suffered both from attack by scarlet fever and
from incidence of return cases.
These facts, it may be submitted, are compatible with the hypothesis that the predominating
agency in promoting the occurrence of return cases of scarlet fever is closely related to some special
influence concerned in producing cases of scarlet fever generally; it is to be sought in some hitherto
unrecognised operative factor in the home environment and not in any of the conditions hitherto
suspected, such as conveyance of infection in particles of skin or in mucous discharges, for the infecting
child often fails to exhibit any evidence of desquamation or of mucous discharges. As regards the
so.called"recrudescence of infection,"it may be surmised that it is the needed conjunction of the
convalescent child and the insect carrier rather than any variation of infectivity of the child that determines
whether or no infection may occur.
It had been hoped that clear light would have been thrown by the St. Pancras figures on the
relative extents to which home and school environments are responsible for favouring return cases.
But here it is essential that, two facts should be kept carefully in mind—in the first place the home is,
perhaps naturally, more likely to fall under suspicion than the school, and hence there is a tendency
to underestimate school influence in this respect; and secondly, a system of keeping back the returned
hospital child from school attendance until it had been examined by one of the school doctors was strictly
carried out. in St. Pancras; thus the return of the child to school was generally two or three weeks and
sometimes longer still after the return home; this would, of course, tend to reduce the number of return
cases ascribed to school influence. As a matter of fact it was found that there was, generally speaking,
no reason for doubting that, the suspected return cases were really infected at home, for only quite
exceptionally was there any reason to think it possible that infection could have been introduced from
the school into the home inasmuch as no recognised scarlet fever had recently occurred in the school.
Analysis of
results
obtained on
examination
of return
cases in St.
Pancras.
Is the return
case infected
at home or
in school.