CARRIERS OF PLAGUE. 



By E. S. GREW. 



Wifli i!lii<itmti(iiis fniiii pliutdoritphs hy tlic coiirfcsy i)/ Dr. C. ,/. Miiiiiii. F.R.S. 



Technically any animal is a carriL-r df plague 

 which has plague, and in the organs or blood of 

 which the plague bacillus resides. In that sense the 

 natives of India are plague carriers : the rats and 

 bandicoots of India are still more emphaticalh" plague 

 carriers. But. in the last resort, seeing that the 

 instances in \\hich a rat suffering from plague could 

 inoculate man with i)lague bacilli must lie so rare as 



Comiiiission have discovcrcii no fact icliidi icoiihf 

 support the siii^ot'stioii that pla^iiiic may effect an 

 entrance into the human or/Jaiiism tliroiis^h t/ie 

 stomach or intestinal canal. The })robabilities 

 ot infection through swallowing an\- number of 

 plague bacilli are cxtremeh' small: and it is 

 justifiable to conclude that in nature, infection of 

 rats by feeding rarely or nc\-er takes place, anil that 



Figure 1. 

 An old Bengalpuni Street. 



All tlu> iKvellin.!; houses .-iit^ abo\e stables, and therefoie, nil the f;u:e nf it, likely In 

 he infested with rats. 



not to be worth considering, the true carriers of 

 plague are the animals which con\-ey the bacilli from 

 rat to rat, or from rat to man, or, in rare instances, 

 from man to rat. These animals are the fleas which 

 infest rats. 



This conclusion, a j)parentl\' so simple, was. however, 

 not reached without long continued investigations, 

 undertaken, at the instance of the Indian Government, 

 by a commission of bacteriologists (uiidei- thr thrci tinn 

 of Dr. C. J. Martin. F.R.S. .and Col. I)a\id liruc,'. 

 F.R.S.), which has been at wdrk since 1'*(I4. Aincnig 

 tile in\-estigations made by the Plagui.' C'ommissitm's 

 bacteriologists have been a number which dispose of 

 the idea that plague can ordinarily be spread h\ 

 jilague bacilli which may be left on the earth — on 

 the floor of infected houses, or on the soil. Nor can 

 jilague be transmitted usually by aerial infection. 

 That is to say, it cannot be transported through the 

 air, or with wind-swept dust. Nor, again, though this 

 belief has had a long currency, can it usualh- lie 

 transmitted through food. flic Indian J^lai^iie 



Figure 2. 

 The interior of a Cooly's Room. 



Pnts and boxes roritaiiiing .nrticles of daily diet are lyin^ all i 

 aftordins; shelter and facility to rats. 



the place and 



rats do not become infected /)v ciilini; the carcases 

 of their comrades. The repetition of these facts 

 has a certain interest at a time when the appearance 

 of plague among rats in Suffolk has created a ver\' 

 distinct prejudice against the use of game, of hares, and 

 e\-en of imported rabbits as food. Everyone would, 

 of course, prefer not tn eat an^' animal which could 

 ))ossibl\- have died from plague, but no one would 

 be in the least likeK' to contract plague bv doing so. 



In \iew, however, of the fact which is now declared 

 Iw the highest authorit\' to be well established, that 

 there have occurred two cases of plague pneumonia 

 in Suffolk, and that there have been a number of 

 cases of plague ainf)ng rats in that neighbourhood, it 

 becomes important to inquire what the probabilities 

 are of any considerable spread of the infection in 

 England. 



In an\- outbreak of idague in a new locality the 

 factors which determine the extent and severity of 

 the epidemic are much more numerous than are 

 generally supposed, and the margin between danger 



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