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12
In view of this progressive increase in the proportionate numbers
of cases at school-age, at a time when the epidemic was rapidly increasing
in intensity, and having regard to other circumstances which are within
my knowledge, I am much inclined to the opinion that the epidemic in
July was, in some degree, facilitated by the existence at that time of
mild, unrecognised cases of the disease, which continued school attendance.
The marked increase in the number of cases at school age in June and
July is very suggestive, whilst in August, when the schools were closed,
the percentage of cases at school age at once fell to 63 from 76 in July.
In view, then, of the very strong probability that the July outburst
was facilitated by the continued attendance at school of cases of
sore-throat, which were in reality mild cases of diphtheria, it is my
intention in the future, should circumstances appear to demand it, to
ask the school authorities to co-operate with me in an endeavour to
exclude from attendance at school all children suffering from sorethroat,
and to concert such measures as may appear to be needful to
carry this endeavour into practice. With diphtheria, as with other
infectious diseases, an epidemic may be stamped out at its commencement
by measures designed to prevent the diffusion of infection amongst
the susceptible population, but once allowed to obtain headway, an
epidemic gets beyond control, as indeed occurred in uly last.
The case mortality, or percentage of deaths from diphtheria and
croup to cases, was 22.9, or 3 per cent. higher than the average of the
preceding 6 years, which shows that, unlike scarlet fever, the type of
disease is more fatal when diphtheria is highly prevalent, than when
restricted within its more usual limits. Part of this higher case mortality
is no doubt, however, attributable to the fact that during the past
year the proportionate number of children under ten years of age
attacked has been somewhat higher than the average of former years,
with a corresponding diminution in the attack rate over ten years of
age. As is well known, the liability to a fatal issue in diphtheria is
greater the lower the age of the person attacked.
Another remarkable feature in the past epidemic has been the large
number of secondary or multiple cases in houses as compared with houses
in which only a single case occurred. During the non-epidemic periods
of diphtheria in Chelsea (1890-5), the multiple cases formed only 18
per cent. of the total cases, whilst during the epidemic period comprising
the last quarter of 1895, and July to November 1896, the multiple
cases formed 40 per cent. of the total cases. In the latter period, in 3
instances 5 in a house were attacked practically simultaneously, in 7
instances 4 in a house were attacked together, and in 13 instances 3 in
a house were attacked. These facts point either to a greater susceptibility
on the part of the juvenile population when diphtheria is epidemic,
than when it is not; or more probably to a virus in a higher state of
activity, and with greater striking power than ordinary.
Enteric Fever.—The number of cases of enteric fever in 1896 was
68, as compared with 76 in 1895. The number of cases in Kensal
Town was only 7, or 10.3 per cent. of the total cases, which is less than
half Kensal Town's due proportion in accordance with its population.