V. 

 BACTERIA IN CROU^OUS PNEUMONIA. 



THE following account of " The Etiology of Croupous Pneumo- 

 nia " is from a paper read by the writer at the annual meeting of the 

 Medical Society of the State of New York, at Albany, N. Y., Feb- 

 ruary 6th, 1889 : 



Acute pneumonia is now generally regarded by the leading clinical au- 

 thorities and pathologists in this country and in Europe as a specific infec- 

 tious disease. Green, in his article on " Inflammation of the Lungs" in 

 Quain's "Dictionary of Medicine," says: "It is maintained by some ob- 

 servers that, like the specific fevers, it is due to a specific cause. Pneumonia, 

 whilst differing from these fevers in not being contagious, resembles them 

 in the typical character of its clinical phenomena and, to a less extent, of its 

 local lesion. The changes in the lung occurring in pneumonia cannot be 

 induced by artificial injury of the organ, and it must therefore be admitted 

 that there is something special in the inflammatory process." 



This "something special "has been demonstrated by recent researches, 

 and it is the object of the present paper to give a historical account of the de- 

 velopment of our knowledge with reference to this specific infectious agent, 

 and of the experimental evidence upon which the claim is founded that the 

 microorganism referred to bears an etiological relation to the disease in 

 question. 



Evidently, if pneumonia is a specific infectious disease, the microorgan- 

 ism which causes it is widely distributed, and the development of an attack 

 depends rather upon secondary predisposing and exciting causes than upon 

 the accidental introduction of the specific agent. 



It cannot be maintained that the disease, as a general rule, is transmitted 

 from individual to individual i.e.. by personal contagion. Clinical expe- 

 rience is entirely opposed to this view, although we have ample evidence 

 that it may occur as an epidemic among individuals who are exposed to the 

 same conditions of environment as in jails, barracks, etc. Thus at Chris- 

 tiania, Sweden, an epidemic of pneumonia occurred in 1847 in the prison, 

 during which sixty-nine of the prisoners were attacked. And again in 1866 

 and 1867, during a period of six months (December, 1866, to May, 1867), a 

 similar epidemic was observed in the same prison sixty -two cases. Other 

 prison epidemics recorded are those at Frankfort in 1875 (seventy-five cases) 

 and in 1876 (ninety -eight cases) ; at Maringen in 1875 (eighty-three cases) 

 and in 1878 (fifty-eight cases) ; at the prison of D'Ansberg in 1880 (one hun- 

 dred and sixty -one cases, with forty-six deaths, in a period of five months). 



Again, we have numerous records of village epidemics and of epidemics 

 confined to single houses. In outbreaks of this character, as in epidemics 

 of typhoid fever, of cholera, and of yellow fever, there is a succession of 

 cases occurring at different intervals, but it does not follow that these cases 

 bear any direct relation to each other. On the contrary, everything indi- 

 cates that, as in the diseases mentioned, in the presence of the infectious 



