!
586
to how far such persons might be possible centres of infection though themselves practically immune, but it also bears upon the question of precautions by examination of incomers, which, if my hypothesis turns out to be correct, would be futile.
5.
I agree with Professor Simpson that insani- tary and overcrowded houses must decrease the resisting power of the inmates, but a careful examination of the records of every case, which by my direction have been kept since 1899, will show that the plague has not been confined to overcrowded houses, one of the severest visitations, such as that at Hunghom:in 1901, were
in new houses, well built, well drained and well lighted. Indeed
my observation of plague in Hongkong coincides with the view expressed in paragraph 359 of the Indian Flague Commission. They
say:-
"On consideration of everything that has been said "in connexion with the influence of Sanitary surroundings "both within and without the house, on the spread of the "plague, it will be clear that we have been unable to find "anything in the nature of statistical evidence or in the "nature of inference from Scientific observations, to "establish the proposition that any of the Sanitary *defects referred to, or any combination of them, exercises "any marked favouring influence on the spread of the "plague".
6.
The Medical Officer of Health has had a
special staff for over three years, and every proposal put for-
ward for dealing with the recurring plague has been accepted as a
matter of course. Every case is traced as far as possible. A
large Sanitary Staff is engaged in disinfection, and all the
tenement houses of Hongkong are systematically line-washed. That
the disinfection as carried out is thorough, 1 assume, yet a
considerable number of cases from houses previously disinfected
are reported after the period at present accepted as the
maximum