30 DAVID J. DAVIS 



studied non-epidemic infections of the respiratory tract, and has clearly shown the 

 similarity, both clinically and pathologically, of the infections due to influenza bacilli 

 and other organisms, such as pneumococcus and M. catarrhalis. Von Jaksch 1 has 

 described a condition, under the name of pseudo-influenza, which is indistinguishable 

 clinically from influenza, but which is not caused by the influenza bacillus. He 

 concluded that it was due often to a streptococcus invasion, because of the large 

 number of these organisms found; in some the cause could not be determined, but 

 he was sure it was not due to influenza infection. 2 



The results of these investigations correspond very well with the 

 findings in the series of influenza cases reported in this paper. While 

 it is undoubtedly true that in many epidemics of influenza Pfeiffer's 

 bacillus exists constantly in the nasal and oral excretions in very 

 large numbers, and to the exclusion largely of other bacteria, and 

 that its presence corresponds with the course of the disease, it is 

 equally true that there occur epidemics, and also sporadic cases, of 

 a condition which appears to be identical with influenza clinically, 

 but which shows Pfeiffer's bacillus only occasionally, and other 

 organisms, such as pneumococci, staphylococci, and M . catarrhalis, 

 very commonly and in large numbers. The most rational interpreta- 

 tion of these facts seems to be that there are a number of organisms 

 which may give clinically the same picture, and which may exist 

 in the respiratory passages either in nearly pure culture; or they 

 may occur together. 



The fact that many cases, indistinguishable clinically from acute 

 influenza, occur both in sporadic and epidemic form not associated 

 with the influenza bacillus, should be more widely known among 

 the medical profession at large. For ever since the great epidemic 

 of 1889-90, almost everything bearing any resemblance at all to 

 influenza is assumed, without a bacteriologic examination, to be an 

 influenza infection. Attention should be called also to the fact that 

 smears of oral and nasal excretions are very unreliable in the diagno- 

 sis of this disease, and that, to be sure of an influenza infection, 

 cultures on blood-agar plates should be made. Clinical data, there- 



1 Berl. klin. Wchnschr., 1899, 36, p. 425. 



Since this paper was written an article upon influenza infections by Jochmann (Deutsches Arch 

 f. klin. Med., 1905, 84, p. 470) has appeared. In 36 cases of epidemic enfluenzas he was able to find 

 influenza bacilli in only 13. Pneumococci and streptococci were very common. He thinks that the 

 clinical picture of acute influenza may be produced by organisms other than the influenza bacilli; 

 especially the pneumococcus, streptococcus, and perhaps the M. catarrhalis. He discusses the occur- 

 rence? of influenza-like bacilli in the infectious diseases and says the organisms from whooping-cough 

 are indistinguishable morphologically and biologically from the bacillus of Pfeiffer. His results agree 

 very well with those given in this paper. 



