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53
it is equally certain that one series of cases could have been prevented if our routine instructions had
been faithfully carried out, whereas on the other hand closure of the room would have allowed an unrecognised
case to wander at large and to infect a number of other children out of school.
Scarlatinal infection seldom spreads through a classroom, but when such is the case local investigation
affords useful information. On October 1st four cases of scarlet fever were reported from
one classroom in the boys' department at Wordsworth-road School. The cases had all occurred during
the preceding eight days. A common source of infection seemed probable and an investigation was
held on the spot. The first case possibly originated from a boy who was suffering from a mild attack
of scarlet fever (thought to be measles at home). This boy had just returned to school, but was only
actually in attendance for less than one hour before being excluded by the head master ; so this source
of infection may be questioned. At all events the first notified case of scarlet fever occurred two days
later and almost certainly infected three other cases sitting in neighbouring desks. It was anticipated
that with the discovery and removal of the primary source of infection the outbreak would cease, as
only one of the secondary cases had shown symptoms of indisposition in the school. This proved to be
the case. As a result of the investigation two other cases appeared to be suspicious and were excluded
and the local Medical Officer of Health was informed. Two other boys suffering from slight sore throats
were also excluded. The only other notified case of scarlet fever occurred two days after the re-admission
of the boy thought to be suffering from measles. They sat next to one another in class and the measles
case subsequently peeled in a manner leaving little doubt as to its scarlatinal nature. With this case
the outbreak appeared to end. But as a result of careful enquiries on the part of the head master and
assistant teacher it has been possible to obtain further detailed information as to the real and insidious
nature of the scarlatinal spread. In addition to the unrecognised case of scarlet fever already referred
to as measles, there were three other obviously missed cases—boys who were absent for 10, 14 and 20
days respectively suffering from sore throat, headache, vomiting and subsequent peeling, etc., and five
slight sore throats absent 2, 5, 10, 12 and 12 days respectively, some of which were associated
with vomiting and fever, others merely with headache. It is to be observed that in this outbreak
no further return " cases occurred. In this classroom, which consisted of 41 boys, aged 9 to 11 years,
7 had previously suffered from scarlet fever, which is an equivalent to an immunity of 17 per cent.—an
unusually high percentage for this age period. After the outbreak had ceased, the apparent immunity
was increased to almost 30 per cent. The real immunity, however—that is to say, including the missed
cases and the slight sore throats—should be represented as just over 50 per cent. No wonder, then, that
such a large proportion of the adult population is apparently immune to scarlet fever. At least two of
the boys, closely associated with scarlet fever cases, but not taking the disease, were found on enquiry
to be protected by previous attacks. The following diagram illustrates the seats occupied by all the
boys in the class—the arrows indicate the probable direction of the spread, though it is difficult to ascertain
how the slight sore throats infected each other.
School scarlatina, showing notified cases, missed cases, slight sore throats and order of incidence in the classroom,
dates of absence and return. Wordsworth-road (B.) school.
DIPHTHERIA.
In the last Annual Report the possibility was pointed out that after some years of diminished
incidence of diphtheria in London the cycle of increased prevalence would probably recur. The figures
for the present year bear this out. It may be that the disease is on the upward slope of such a curve