324 BACTERIA PATHOGENIC TO MAN 



alveoli become filled. The influenza bacilli are found crowded in be- 

 tween the epithelial and pus cells and also penetrate the latter. There 

 may be partial softening of the tissues, or even abscess formation. 

 Bacilli are found in fatal cases to have penetrated from the bronchial 

 tubes not only into the peribronchitic tissue, but even to the surface 

 of the pleura, and rarely they have been obtained in pure cultures in 

 the pleuritic exudation. The pleurisy which follows influenza, however, 

 is usually a secondary infection, due to the streptococcus or pneumo- 

 coccus. 



Presence of Influenza Bacilli in Chronic Influenza and in Tuberculosis. 

 Ordinarily influenza runs an acute or subacute course, and not infre- 

 quently it is accompanied by mixed infections with the pneumococcus 

 and the streptococcus. Pfeiffer was the first to draw attention to certain 

 chronic conditions depending upon the influenza bacillus. Bacilli may 

 be retained in the lung tissue for months at a time, remaining latent 

 a while, and then becoming active again, with a resulting exacerbation 

 of the disease. Consumptives are liable to carry influenza bacilli for 

 years and are particularly susceptible to attacks of influenza. Williams, 

 in the examination of sputa in cases of pulmonary tuberculosis, has 

 found abundant influenza bacilli to be present in a large proportion of 

 the samples of sputum from consumptives, and this not only in winter 

 but also in the summer, when no influenza was known to be present 

 in New York. Taken together with results elsewhere, this indicates 

 that at all times of the year many consumptives carry about with 

 them influenza bacilli, and that very likely many healthy persons as 

 well as persons suffering from bronchitis also harbor a few. Given 

 proper climatic conditions, we have at all times the seed to start an 

 epidemic. 



The influenza bacillus does not occur, as a rule, in the blood and 

 probably does not develop there. It is found at times in otitis media 

 accompanying influenza, and has been found in the meninges in cases 

 of meningitis. So far as positive results have shown, influenza would 

 seem to be almost always a local infection confined chiefly to the air 

 passages. The general, cerebral, gastric, and other symptoms produced 

 are due to the absorption of the toxic products of the specific organism, 

 these poisons being particularly active in their effects on the central 

 nervous system. 



The discovery of this bacillus enables us to explain many things, 

 previously unaccountable, in the cause of epidemic influenza. We now 

 know, from the inability of the influenza bacillus to exist for long 

 periods in dust, that the disease is not transmissible to great distances 

 through the air. We also know that the infective material is con- 

 tained only in the catarrhal secretions. Sporadic cases, or the sudden 

 eruption of epidemics in any localities from which the disease has been 

 absent for a long time, or where there has been no new importation 

 of infection, may possibly be explained by assuming that the bacilli, 

 as already mentioned, often remain latent in the lungs or bronchial 

 secretions of the body for many months, and perhaps years, and then 



