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the case of a very badly infected house we have generally persuaded the inmates to evacuate
it before disinfection and have kept them away for ten days if possible. Our reason for
doing this has been to prevent re-infection of the house by persons in whom the disease
might be incubating at the time of disinfection.
Seeing the good which results from this system of working, it is not difficult
to say that the plan of operations ought to be when the next epidemic breaks out.
At the very commencement of the outbreak, the houses which have been notoriously badly
infected in previous years (and there are many such), ought to be, in my opinion, well dis-
infected from top to bottom, even before any case of plague has been discovered in them,
I do not advise that any attempt be made to evacuate those houses (except perhaps for two
or three days while they are drying), as the accommodation in the camps is limited and
may be wanted for other people whose houses it may be thought much more desirable to eva-
cuate. The kit found in these houses, had better, I think, be let alone, with the exception
of such articles as bundles of dirty rags which might be opened out and spread in the sun,
or better disinfected. Rat holes, of course, will be dealt with, as at present, by flushing with
Perchloride solution and tarring. It may be said that it would be better to keep a care-
ful watch on these houses, and according as a case of plague is discovered in any one of
them, to thoroughly disinfect that one immediately, but I should much prefer the plan of
disinfecting the lot of them at the start for the following reasons : (1) These houses
have become badly infected every time or nearly every time plague has become epidemic in
the city and it is reasonable to suppose that they will continue to become infected in future
epidemics. After complete disinfection, they as a rule remain free from infection for two
months. Therefore by disinfecting them every two months we can keep most of them free
from infection for the whole epidemic. (2.) When the first case is discovered in one of
these houses it is very likely that several of the other inmates will have the germs of the
disease (in the incubation stage) in their systems. These when their own house is being
disinfected, may go elsewhere, develop the disease, and so infect fresh houses, or they may
re-infect their own houses.
That an epidemic of plague is found among rats before it attacks
human beings, is a coincidence has not escaped the notice of Dr. O'Brien
and he points out that when rats are found to be dying, it will be then
the proper time to commence the disinfection of the worst infected houses
of the kind just mentioned. He remarks as follows :—
I may allude here to the very interesting fact, that rats are generally found to be dying
in large numbers some six weeks or two months before the plague becomes epidemic in human
beings. This occurrence, which has, I think, been noticed every time an epidemic of plague
has broken out in Bombay, would seem to show that the germ of plague, after it has passed
through the system of the rat, takes some time to reach a stage in which it can develop the
disease in human beings, and ought to have an important bearing on our preventive measures
in future years. It furnishes additional evidence of the necessity of disinfecting houses with
a bad history before any case of plague is discovered in them.
With regard to houses that are found to be not so badly infected he
advises that where plague rats are found and the occupants have been
attacked, it is best to disinfect whole floors or if possible the whole house.
"Rats would shift their quarters to other parts of the house to escape
the wetting they would get from the solution, and so spread the disease to
the other floors, hence the necessity of disinfecting the entire house."
Dr. O'Brien states in conclusion thus :—
That nothing has been so well impressed on me during my experience of the disinfection
carried out in Bombay this year, than the necessity for constant supervision of the subordi-
nate staff.