?10
Method of its performance.
Records.
22.   The method of performing the operation calls for no  description  here.    The
records concerning inoculation were similar to
those described in the reports on inoculation
for 1899-1900. though it should be stated that
(c)wing partly to the relative weakness of the staff and partly to the conditions which
have been referred to in dealing with the leading information, it is not possible to attain
or maintain as  complete records concerning inoculation as in former years.
Effects of inoculation.
23.    From what has  been stated above it  will be  evident that  the statistical   evi-
dence of the  value  of  inoculation during the
year under report is very incomplete.
In only very few instances were data obtainable for comparing the incidence of out-
breaks of plague upon inoculated or uninoculated communities living under otherwise similar
conditions. A comparison based upon the total figure of the Province would be of no value,
because on the one hand in some districts only isolated cases of plague occurred among
large populations, and in the others a large number of inoculations were performed
after outbreaks of plague had ceased. Such data as were obtained are dealt with in
the reports of the districts concerned, but it may be said here that in nearly every
instance inoculated communities suffered much less severely from plague than the unin-
oculated.
The number of attacks and deaths among inoculated persons are shown in State-
ments 1 (Appendix A) and 9 (Appendix B) in the latter of which the number and fatality of
attacks at varying periods after inoculation are shown. In Statement No. I it is shown that
of the 235,776 persons inoculated in the British districts, 881 were attacked with plague, of
whom 309 died. The figures are included in those of the total number of cases and deaths
from which they must be deducted to show the number of cases and deaths among
uninoculated persons. These amounted to 266,700 and 173,732 respectively. The fatality
of attack among the uninoculated was 65.14 and among the inoculated 35.07. Attention
may be drawn here to the remarks made by several officers that although plague occurrences
among uninoculated persons may have been concealed, the people promptly brought to
light all such occurrences among the inoculated. However doubtful therefore the value of
the statistics concerning plague occurrences may be, there seems little room for doubting
that the figures showing the fatality of attacks among the inoculated are fairly correct,
and unless it be held that the number of unreported cases of plague among the uninoculated
was so great as to materially reduce the figure showing the fatality of attacks among this
class, that the inoculated persons who were attacked with plague had nearly twice as great
a chance of recovery than the uninoculated. Should it be held that a very large number
of cases among uninoculated persons were concealed, the comparison of the incidence of
plague attacks among uninoculated and inoculated becomes more unfavourable to the former.
In Statement No. 9 (Appendix B) the 881 cases of plague among inoculated persons
are shown according to the period which elapsed between inoculation and attack. The
figures shown for each period in different districts are often too small to be of much value,
but when grouped are sufficiently large to permit of comparison being made between them.
It will be seen that though the figures for different districts vary considerably, the
fatality of attacks among the inoculated is much less at all periods except during the
first week after inoculation than among the uninoculated in every district, and that taking
the figures for all districts together attacks even during the first week after inoculation
were slightly less fatal than attacks among uninoculated persons. It would appear from
the statement that the protective value of inoculation against death from plague increases
up to three months and then declines, though even after four months the inoculated are
better off than the uninoculated.
Infection.
Manner in which  the  infection of  plague is con-
veyed.
Human agency.
24.    All officers, Civil and Medical, were convinced that plague is almost invariably
conveyed from one place to another by human
intercourse, either directly by persons suffer-
ing from the disease or indirectly in infected
clothing and bedding or other personal effects.
Rats.
The only other possible carrier  of infection mentioned in the district reports is the
rat, and the instances  in  which  it  appeared
more probable that villages had been infected
by rats than that the disease had been introduced by human agency were very few.
The statements made in the reports of most badly-infected districts that in many
villages rats died before any human beings were attacked cannot be taken as conclusive
evidence that infection was introduced by rats because it has to be considered along with
the equally prevalent statements in the reports of district officers that the earlier cases
of outbreak were usually concealed.
From the facts recorded in certain reports of the migration of rats from infected
to uninfected villages, there can, however, be little doubt that these animals do occasion-
ally introduce the infection of plague into previously uninfected villages.