262 PUBLIC HEALTH BACTERIOLOGY 



Methods of Diagnosis. 



Bubonic. (i) Prepare the skin over a bubo, and remove 

 some juice by aspiration with a sterile hypodermic syringe, 

 the needle of which is plunged into the bubo ; (2) Make 

 smears, and cultures on agar and salt agar ; (3) Inoculate 

 a guinea-pig with some of the material, by rubbing it in on 

 the shaven skin with a glass spatula, or by subcutaneous 

 injection. 



In bubonic plague, a diagnosis in many cases can be 

 made by microscopic examination alone, as in no known 

 condition other than plague do bacilli with the same 

 morphological characters occur in such numbers in the 

 lymphatic glands. 



Pneumonic. (i) Microscopic examination of the 

 sputum ; (2) Make cultures, inoculate a guinea-pig ; also 

 a rat by smearing the sputum on its nasal mucous- 

 membrane. 



In pneumonic plague, a positive diagnosis should not be 

 given from microscopic examination alone, especially in 

 a plague-free district, as bacilli morphologically resembling 

 the plague organism may occur in the sputum in con- 

 ditions other than plague. 



Post Mortem of Rat Dead of Plague. Subcutaneous 

 injection of the flaps of the abdominal wall is noted. Fluid 

 in the pleural cavities, haemorrhagic oedema of the neck 

 glands, a creamy mottled appearance of the liver, and a 

 somewhat similar appearance of the spleen. The Indian 

 investigators laid stress on an abundant, clear, pleural 

 effusion. The neck glands are chiefly involved in the 

 rat because the flea prefers the skin of the neck ; in 

 California and Glasgow, however, the cervical bubo was 

 not so commonly found as in India. 



In chronic rat plague, enlargement of the spleen, with 

 the formation of nodules in it containing plague bacilli, 

 was the usual finding. 



Prophylaxis. 



Destruction of rats, by poisoning, trapping, ferreting, 



and virus. 

 Separation of rats from mankind by better drainage, 



paving of yards, concrete floors, and general 



repairs. 



