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27
DIPHTHERIA.
117 casus of Diphtheria were notified, and 8 deaths occurred
from the disease. 3 other notifications were received, but subsequently
withdrawn; 4 cases were wrongly diagnosed, but the
notification was not withdrawn.
Although the number of notifications was higher by 17 than
that of the previous year, the number of deaths remained at the
same number, with the result that the fatality of the disease was
reduced to 6.8 per cent.
There are few phenomena more remarkable than the
apparently lessened fatality from Diphtheria which has been
noticed during the last 10 years. If we take the last 10 years,
1904-1913, and compare them with the previous 14 years following
the introduction of the Infectious Diseases Notification Act, we
find that the case-rate in 1904-1913 is nearly 50 per cent. higher
than in the earlier period, but the death-rate in the earlier period
is 50 per cent. higher. The actual figures are: 1890-1903, average
annual case rate, 1 per 1,000; death-rate, .21 per 1,000. In
1904-1913, the figures are: Case-rate, 1.46 per 1,000; death-rate,
.13. The death-rate in the earlier period is understated, for, in
addition to the fact that outside deaths were not included in the
returns, the more accurate means of diagnosis would tend to
magnify the death-rate in the later period.
Various reasons have been assigned as the cause of this
reduced fatality of the disease, but many of these are based on
the assumption that the type of disease is now of a much milder
character than formerly. There is a widespread impression that
the disease is now milder in character, though the figures which
are adduced in favour of this are hopelessly inaccurate, and there
is no definite proof of the relative mildness of the disease. To
offer explanation of a cause which is not proved to be existent
is unprofitable, if not foolish, and the most frequently offered is
probably the most fallacious of all. This is the explanation which
attributes the mildness to a gradually accumulating inherited
immunity, affecting the community as a whole. But why should
this immunity only show itself during the last decade or two?