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1907]
72
quinquennial periods. In the former period the cases averaged 722 annually,
and in the latter 585, but in 1906 and 1907 they respectively numbered 4.37 and
486, so that the decrease has been maintained.
It is not easy to say how far the prevalence of the disease in the present
time compares with that of the past, because formerly the fatality among
those attacked was very high, while latterly it has been comparatively low,
owing to the introduction of the serum treatment, so that any exact comparison
is impossible. It may be stated, however, that formerly about 25 per cent.
of the persons attacked died, whereas during the last two years, in Islington
only 8½ per cent. succumbed.
We can, however, arrive at an estimate, if we calculate that the mortality
represented 25 per cent. of the cases in the quinquennium 1861-65, consequently
the 194 deaths in that period would represent 776 cases, as against 2,923 in the
five years 1901 05. The population has, however, more than doubled since then, so
that a correction must be made for the increase, and consequently the 776 would
become 1,575, so that probably a truer contrast would be 1,575 as against
2,923. Thus, however we consider the question, there has been an enormous
increase in the prevalence of Diphtheria since the middle of the last century,
although just now there are, as we have seen, strong indications of a marked
decrease.
Table XLV.