266 THE INFECTIOUS DISEASES. 



BUBONIC PLAGUE. (Oriental Plague ; Black Death.) 



Types of the Disease. This disease presents three main types the bu- 

 bonic, pulmonary, and gft^ti^mife 



The mosTcommon is the Bubonic, which is characterized by an intense 

 mflanjniQ,tory hyperplasia of the lymph-nodes, most frequently the iu_- 

 guinal or ..axillary. Hie surrounding tissue may be involved; haemor- 

 rhage, necrosis, or suppuration in the nodes may occur. Coincident with 

 these local reactions there may be albuminous degeneration, focal necro- 

 sis, and leucocytosis from toxaemia, or secondary foci of inflammation in 

 the spleen or lungs or liver. A second type of the infection is the pul- 

 monary, in which larger -or smaller areas of the lungs are involved iu 

 broncho-pneumonia with associated secondary involvement of the bron- 

 chial lymph-nodes. In the septiccemic type of bubonic plague there may 

 be a general involvement of the lymph-nodes and nodules of the body 

 with the marks of toxaemia, without an indication of the point of primary 

 infection. * 



In all these various phases of the disease the plague bacillus may be 

 present often in enormous numbers in the primary buboes and in the 

 secondary lesions and in the viscera ; in the consolidated areas and in the 

 sputum in the pulmonary type, and in the septica3inic phases, in the blood. 



Characters of the Plague Bacillus. 



The plague bacillus was discovered in 1894 by Kitasato and Yersin, and its role as 

 the excitant of the disease was soon established. It is a short, thick, motile, round-ended 

 bacillus, often staining more deeply at the ends than in the middle. It sometimes 

 grows in chains and may be capsulated, not forming spores; it is decolorized by Grain's 

 method. It grows readily though not voluminously on the ordinary culture media at 

 blood heat. a This organism is killed by drying for a few days and by exposure to sun- 

 light for a few hours. Subcutaneous inoculation in guinea-pigs and rabbits is followed 

 by local hemorrhagic and serous inflammation with typical involvement of the regional 

 lymph-nodes and by septicaemia. Death may follow in from one to five or six days 

 with albuminous degeneration of the viscera, hyperplasia of the spleen, and petechial 

 hemorrhages. 



Portals of Entry. The chief portals of entry in man are abrasions 

 or wounds of the skin, the lungs, and the intestines. The spread of the 

 infectious material in overcrowded and unsanitary districts may readily 

 take place by rats, which are very susceptible to the disease and may be 

 infected by feeding. Through mosquitoes and flies also the bacilli may 

 be conveyed from man to man or from dead rats or their dejecta to man. 



Preventive Inoculation has been largely practised in the East by. the 

 Haffkine method. This consists in the subcutaneous injection of beef- 

 tea cultures of the plague bacillus, which have been killed by heating. 

 Moderate local inflammatory reaction and slight fever may follow the 



1 For a resume of lesions of plague, sec Flexner, Trans. Assn. Am. Phys., vol. xvi., 

 p. 481. 



* See article by Dieudonne in Kolle and Wassermann's "Handbuch der Mikroor- 

 ganismen," Bd. ii., p. 475. 



