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29
29), during which steam disinfection had been carried
out, can be compared with those of five years (1930-34),
during which it had been abandoned. The table shows
at a glance the total number and also the percentage of
secondary cases occurring in premises from which the
original cases had been removed previously. By way of
explanation, it should be pointed out that, in the final
comparison, secondary cases occurring within a week
of the primary case have been excluded, the reason
being that such cases occurring within the known
incubation stage of the two diseases may have been
infected by the primary case before removal to hospital.
Period.
Steam
Disinfection.
Disease.
Cases
Notified.
Cases
Removed.
Secondary
Cases
After
7th Day.
Percentage
of
Secondary
Cases.
1925/6/7/8/9
Practised.
S.F. 2,054 1,815 80 6.08
Diph. 1,538 1,272 59 4.68
Total 3,592 2,587 139 5.37
1930/1/2/3/4
Abandoned.
S.F. 2,542 1,683 104 5.51
Diph. 1,050 896 33 3.68
Total 3,592 2,579 137 5.31
It will be seen that, in the case of scarlet fever, the
percentage of secondary cases has dropped from 6.08
per cent. to 5.51 per cent., whereas the relative figure
for diphtheria has fallen from 4.63 per cent. to 3.68 per
cent. during the two periods under review. When
comparison is made between the total figures (including
both scarlet fever and diphtheria) it will be seen that
the percentage of secondary cases has diminished from
5.37 (with steam disinfection) to 5.31 (without steam
disinfection).