i68 DISEASES DUE TO BACTERIA 



The isolated cases of pneumonic plague which occur in Siam do 

 not appear to have any tendency to cause extension of the disease, 

 and persons coming into intimate contact with such patients do not 

 become infected. The Manchurian experience was very different 

 (Manuad). 



1914. During the plague in New Orleans, there was" one quarter 

 where, although the people were living over a hotbed of infection, no 

 human case ever occurred. It is suggested that the rat population was 

 so large that human blood did not present any temptation to the rat 

 fleas, as their natural hosts, the rats, provided ample food (Akin). 



1916. There was plague in Bristol during July in humans and 

 rats. Active measures eradicated it. Eight out of seventy-four rats 

 caught in the rag factory were infected. The 200 tons of rags were 

 then destroyed by fire, an excellent means of disinfection. 



This is the twelfth British seaport in which plague has occurred 

 within the past fifteen years, apart from a sharp pneumonic attack in 

 Essex about ten years ago, when a few people died and several varieties 

 of animals were found infected. 



History shows that plague is wont to visit a country once in 300 

 years; the last epidemic occurred in Britain some 300 years ago; 

 another is due now (Cantlie). 



THE CAUSATIVE BACILLUS. 



The B. pestis of Kitasato and Jerson is found in the initial 

 cutaneous vesicle, buboes, spleen, blood and sputum in pneumonic 

 cases. 



Monkeys, rats, guinea-pigs have been successfully inoculated with 

 typical symptoms. 



Bovines and equines give local reaction only. 



Canines, birds and reptiles are apparently immune. 



Human plague is an offshoot of rat plague. 



In glucose the bacillus forms acid, but not gas. 



In lactose it gives no reaction. 



In broth with cocoa-nut oil it forms flocculent tapering masses. 



Haffkine's stalactite growth, verv delicate and verv readilv broken 

 off. 



The pseudo-tuberculosis bacillus is much the same; inoculating 

 guinea-pigs is required to differentiate them ; this kills in three weeks, 

 the plague bacillus in three days. 



B. pestis is a short, oval rod with rounded ends, capsulated singly, 

 but in cultures they grow in chains. It does not form spores. No 

 true motility. Stains readily with basic aniline stains. Gram- 

 negative; grows on ordinary media at body heat; flourishes best in 



