A FURTHER NOTE UPON THE INFLUENCE OF ATMOSPHERIC 



TEMPERATURE UPON THE SPREAD OF 



PNEUMONIC PLAGUE 



By Oscar Teague' 

 (From Cornell University Medical College, New York) 



Plague has raged in India for almost two decades, and has 

 carried off several millions of victims. The epidemic has 

 remained essentially bubonic in type. Although 1 per cent or 

 more of all the cases have been plague pneumonias, these 

 numerous scattered cases have not led to epidemics of pneu- 

 monic plague. That plague pneumonia may assume epidemic 

 proportions under certain circumstances was demonstrated most 

 conclusively in Manchuria during the winter of 1910-1911 by 

 one of the most virulent epidemics of modern times. Teague 

 and Barber ^ recently offered the following explanation of the 

 rapid spread of pneumonic plague in Manchuria and the failure 

 to spread in India. 



We believe we are justified in concluding from these experiments that 

 were the plague organisms sprayed under similar conditions they would 

 persist longer than cholera vibrios, but a shorter time than prodigiosus 

 bacilli. Hence, it seems probable that the plague bacilli contained in fine 

 droplets of pneumonic-plague sputum would suffer death from drying in a 

 few minutes unless they were suspended in an atmosphere with an extremely 

 small water deficit. Infection in pneumonic plague follows the inhalation 

 of droplets of pneumonic sputum and obviously the longer these droplets 

 remain suspended in the air, the greater is the danger of infection. As 

 has just been stated, these fine droplets disappear very quickly except when 

 they are suspended in an atmosphere with a very small water deficit. Such 

 an atmosphere is, under ordinary circumstances, of common occurrence in 

 very cold climates, whereas it is extremely rare in warm ones. Hence, 

 since the droplets of sputum persist longer, the plague bacilli remain alive 

 longer in the air, and there is a greater tendency for the disease to spread 

 in cold climates than in warm ones. 



During the Manchurian epidemic the temperature at Harbin 

 (where the great majority of deaths occurred) ranged between 



^ Assistant in experimental pathology, Cornell University Medical College, 

 New York. 



' This Journal, Sec. B (1912), 7, 172. 



241 



