268 ATMOSPHERE IN RELATION TO HUMAN LIFE AND HEALTH. 



INFLUENZA. 



No disease of the epidemic character has seemed to depend more on 

 the constitution and infection of the general atmosphere than influenza. 

 Its rapid spread, its apparently capricious outbreaks at places wide 

 apart, the almost simultaneous attack, as it seemed, upon a large 

 fraction of the population of a country, masked the true method of 

 progress. But when its track and behavior were carefully followed, 

 these facts became clear — that it never traveled faster than human 

 beings; that many mild cases existed in every large town long before 

 it was generally recognized ; that it took at least six weeks to attain its 

 maximum after the occurrence of the first cases; that its rapidity of 

 advancement from east to west and from town to village corresponded 

 roughly and generally with the rapidity of means of transit; that large 

 numbers of people not exposed to personal infection escaped; that 

 islands unvisited through the period, deep-sea fishermen, and light- 

 house keepers escaped, except in a very few instances where they had 

 been ashore or received communications from infected places; that 

 susceptible persons very easily caught the pest within a few days after 

 exposure to infection in the ordinary sense; that infection was some- 

 times conveyed by parcels, letters, clothing, etc., from patients or 

 infected places; that ships which had cases on board were the means of 

 starting it in islands at which they stopped; and that in previous epi- 

 demics the spread was often so very slow as to be quite unaccountable 

 by any atmospheric quality. Moreover, when the bacillus of influenza 

 was identified, it became easy to comprehend how the countless multi- 

 tudes of exceedingly small organisms alive in the sputum and saliva 

 might be disseminated in the air of buildings and of public conveyances 

 and transmitted from place to place by commerce and the post. The 

 general atmosphere either diffused them to harmlessness or killed 

 them, for there was no evidence of influenza reaching an isolated 

 community by means of wind blowing from a place where it was 

 prevalent. But in confined or foul air they were capable of passing 

 through many feet without losing their capacity of infection. They 

 were experimentally shown to thrive abundantly on the gum of an 

 envelope, 1 and since many patients wrote letters, this must have been 

 rather a common mode of transmission, the organic motes flying upward 

 to the breathing organs of the recipient on his breaking the fastening. 

 There is no difficulty in explaining the quick diffusion of an epidemic 

 having the qualities of influenza among a susceptible population. The 

 minuteness of the bacilli, their vast numbers in the breathing organs, 

 the short period of incubation, and the early infectiveness, and in mod- 

 ern times the immense daily communications between distant places, 

 have to be taken into consideration. If examination of matter of the 



l Dr. Kleiu, British Medical Journal, February, 1894. 



