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122
Annual Report of the London County Council, 1911.
The following were the schools affected and except Manchester-street their position is shown on
the map and marked by the letters attached to the name.

About five per cent, of the children in those schools had attendance affected. At Winchesterstreet
in the centre of the district it was 10.6, the next four nearest schools 5.2, the rest 3.9, and, indeed,
in the four most remote only 2.3 per cent, were affected by actual illness or exclusion as contacts.
On the map sketched in Figure 5, each circle represents a house known to us as
invaded during 1911 by scarlatina. Houses marked with a cross did not affect school children. The
plain circle means that children from that house were excluded from Winchester-street, although no
school children were sufferers. Houses marked with a dot in the centre indicate children, but not sufferers,
excluded from other schools. Houses where school children were sufferers are marked by half black
circle; in Winchester-street cases the division is horizontal, in other cases vertical.
With the figures already given, and the evidence shown on this map, it can be seen that each
of these schools had repeated introduction of the disease, but the only active part they seemed to
take was in the discovery of early or mild cases, the "throat cases." Of these 35 were brought to
light in school compared with 149 otherwise notified, nearly 20 per cent., which notification ceasing
during holiday times forms a large factor in the supposed holiday influence on the disease deduced
from statistical notification returns. Otherwise the schools are almost passive as regards a scarlatinal
prevalence, and are only affected according to their proximity to an invaded district.
When the proportions of children in boys' and girls' departments whose attendance was affected
by the disease are examined, whilst the proportions of contacts excluded are almost identical, the
number of sufferers among the girls is in considerable excess compared with boys. These facts

Although this enquiry is not full enough to establish, it is entirely confirmatory of the suggestion
put forward in a previous report that perhaps eighty per cent, of the population may be regarded as
comparatively immune to scarlatina as now prevalent, and that only the remaining twenty per cent,
are likely to take it under the usual conditions of exposure. This comparative immunity is no doubt
mainly inborn, and contributed to by conditions of good health. It explains the escape of schools,
and the want of any marked influence of schools in distributing the disease. It also explains the
strange but usual mode of invasion among a school population where the first few cases occur almost
simultaneously in different departments and in different classes. The escape of the boys compared
to the girls, the latter more exposed in the homes, and the excess of the less immune infants attacked
all bear out the proposition.
To demonstrate an inborn or family immunity would be exceedingly difficult, but on distributing