272 PUBLIC HEALTH BACTERIOLOGY 



contact with cases of the disease or suspected cases. The 

 best form of mask is a three-tailed gauze bandage with 

 a pad of cotton-wool. It should be destroyed or dis- 

 infected after each exposure to infection. The epidemic 

 was, almost without exception, one of primary pneumonic 

 plague, with an incubation period of from two to five days. 

 An increased temperature and pulse-rate are usually the 

 earliest signs observable, but a diagnosis cannot be made 

 until the organisms are recognized in the characteristic 

 blood-stained sputum. 



An accurate diagnosis can only be made by a bacterio- 

 logical examination of the sputum to exclude pneumonic 

 infection due to other micro-organisms. Since the evidence 

 points to the conclusion that in the epidemic all the cases 

 became septicemic, an examination of the blood micro- 

 scopically or culturally may be a valuable aid in diagnosis. 

 The physical signs of lung involvement are too indefinite 

 and appear too late in the course of the disease to be of 

 diagnostic value, and even in cases in which the condition 

 of the patient is grave they may be very slight. 



The fatality has been^ extremely high, scarcely any 

 recovering. The general experience has been that no 

 method of treatment has been of avail in saving life, but 

 that the serum treatment seems in a few instances to have 

 prolonged it. The decline of the epidemic has not been 

 due to any loss of virulence of the bacillus, but probably 

 to the preventive measures which were enforced either in 

 accordance with scientific methods or by the efforts of 

 the people to protect themselves. 



The statistics of prophylactic inoculation collected 

 during the past epidemic do not allow of any definite 

 conclusion being formed about their value in plague 

 pneumonia ; but in bubonic plague it was argued that 

 some degree of protection is conferred by the use of 

 vaccines. Further experiments in animals are recom- 

 mended, in reference to securing immunity against 

 pneumonic plague infection. {Lancet, 191 1, vol. I, 

 pp. 1614-16.) 



