STUDIES ON PNEUMONIC PLAGUE AND PLAGUE 

 IMMUNIZATION. 



II. THE METHOD OF TRANSMISSION OF THE INFECTION IN 



PNEUMONIC PLAGUE AND MANNER OF SPREAD OF 



THE DISEASE DURING THE EPIDEMIC. 



By Richard P. Strong and Oscar Teague. 

 (From the Biological Laboratory, Bureau of Science, Manila, P. I.) 



Immediately after establishing our laboratory in Mukden, 

 experiments were undertaken with the idea of elucidating the 

 method of transmission of the infection in pneumonic plague 

 and the manner of spread of the disease during the epidemic. 



The sputum of pneumonic-plague patients in the advanced 

 stages of the disease always contains enormous numbers of 

 plague bacilli. The temperature of the hospital wards at Mukden 

 was sufficiently low so that the expired air became immediately 

 condensed to a vapor which was clearly visible to the eye as 

 it issued from the mouth, and frequently could be seen for a 

 distance of 30 centimeters or more from the face. In many 

 of the patients advanced pulmonary oedema was present and 

 the respirations were sometimes very forcible and sometimes 

 even stertorous. Therefore, experiments were carried on to 

 show, first, whether in cases of pneumonic plague the specific 

 organism of this disease became disseminated into the air by 

 the expired air or vapor arising from the breath in ordinary 

 or dyspnoeic respiration, and, secondly, whether this organism 

 was disseminated by moderate attacks of coughing in pneumonic- 

 plague cases in which the cough did not result in the expulsion 

 of particles of sputum visible to the naked eye. These questions 

 were studied extensively by means of exposing Petri dishes 

 containing agar before undoubted plague cases and of then 

 identifying the organisms which developed on the media by 

 the usual bacteriological methods and particularly by animal 

 inoculations. 



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