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33
Disinfection.
The experiment referred to in my report for last
year is frequently cited by officers of my department to
demonstrate the unreliability of terminal disinfection.
It is considered that this experiment is of sufficient
importance to warrant repetition of the description
given last year, which is as follows:-
" Five full years have now elapsed since routine steam
disinfection was discontinued, and the following table
shows in summary form the results of the last five years
compared with those of the five years immediately
preceding. In the table the results of five years (192529),
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.
Per-
Second- centagc
Steam Cases i Cases ary of
Period. Disinfection. Disease. Noti- Re- Cases Second-
fied. moved. After ary
7th Day. Cases.
S.F. 2,054 1,315 80 6.08
1925/6/7/8/9 Practised. Diph. 1,538 1,272 59 4.63
Total i 8,592 2,587 139 5.37
S.F. 2,542 1,683 104 5.51
'030/1/2/8/4 Abandoned. I Diph. 1,050 896 33 3.68
Total 3,592 2,579 137 5.31