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SOME POINTS OF GENERAL INTEREST ON THE 
SUBJECT OF PLAGUE 
By Major Ci E. Southon, I.M.S. 
The endeavour in this paper is to place before members 
some points of general interest on the subject of plague. 
The history of plague will first be briefly traced, then 
the root-cause of the disease, viz. Bacillus pestis, will be 
dealt with by tracing it through the laboratory and noting 
its vitality both inside and outside the living organisms of 
various animals, with particular reference to the principal 
host — the rat. 
The next step will be to examine the life history, habits, 
and morphology of the connecting link between the rat and 
human beings, viz. the flea. 
The final stage is to consider plague in its relation to man. 
To summarise, the various steps are : the Bacillus pestis, 
the rat, the flea, and man. 
Definition . — Let us first define our subject. Plague is an 
acute, infective, febrile disease, accompanied by inflammation 
of the lymphatic glands, and caused by a micro-organism, the 
Bacillus pestis. 
History 
In thinking of plague, some of us are apt to regard it as 
a comparatively new disease, or at any rate our thoughts do 
not carry us farther back than the Great Plague of London, 
in the year 1665. But plague has been with us from time 
immemorial. Thus we find a reference to it in the writings of 
a physician, Rufus of Ephesus, about a.d. 100, and he was 
referring to an outbreak in the third century before Christ. 
The Greeks also wrote of ‘ pestilential buboes,’ and we meet 
it again in the Great Plague of Justinian, which started from 
Egypt in a.d. 542, and spread over a large part of Europe. 
At the end of the seventh century, bubonic plague was recorded 
