BACILLUS INFLUENZA 541 



escents or even of normal individuals for many years. They are found 

 for long periods in the lungs of those suffering from tuberculosis. To 

 such sources, probably, are attributable the sporadic cases developing 

 constantly in crowded communities. Occasional reactivation of the 

 influenzal infection may often aggravate the condition of phthisical 

 patients. Cases of influenza observed apart from the large epidemics 

 are rarely due to an umnixed Pfeiffer bacillus infection, but are usually 

 due to a mixed infection, including with this bacillus, pneimiococci, 

 streptococci, and other secondary invaders."^ This may, in part, account 

 for the frequently atypical courses of such attacks. 



Dr. Anna WiUiams ^ has recently studied hemoglobinophilic bacilli 

 isolated from the eye in cases of trachoma. She believes that trachoma 

 is probably caused by bacteria of this group. At first an acute infection 

 or acute conjunctivitis occurs. Later when chronic productive inflam- 

 mation supervenes the clinical picture is that of trachoma. 



Experimental infection of animals reveals susceptibility only in 

 monkeys. Pfeiffer and Beck^ produced influenza-like symptoms in mon- 

 keys by rubbing a pure culture of the bacillus upon the unbroken nasal 

 mucosa. Intravenous inoculation in rabbits produced severe symptoms, 

 but the bacilli do not seem to proliferate in these animals, the reaction 

 probably being purely toxic. Cultures killed with chloroform may pro- 

 duce severe transient toxic symptoms in rabbits.^ Immunity produced 

 by an attack of influenza, if present at all, is of very short duration. 



Bacteria Closely Related to Influenza Bacillus. — Pseudo-influenza 

 Bacillus. — In the broncho-pneumonic processes of children, Pfeiffer ^ 

 found small, non-motile. Gram-negative bacilli, which he was forced to 

 separate from true influenza bacilli because of their shghtly greater size, 

 and their tendency to form threads and involution forms. These micro- 

 organisms are strictly aerobic and grow, like true influenza bacilli, only 

 upon blood media. They are differentiated entirely by their morphology 

 upon twenty-four-hoiu--old blood-agar cultures. Wollstein,' who has 

 made a careful study of influ&nza-like bacilli, both culturally and by 

 agglutination tests, has come to the conclusion that these bacilli are so 

 similar to the true influenza organisms that the term pseudo-influenza 

 should be discarded. Strains of similar bacilli isolated from cases of 



' Tedesco, loc. cit. 



^ Dr. Anna Williams, Inter. Congress of Hygiene and Demography, Washington, 

 1912. 3 Pfeiffer und Beck, Deut. med. Woch., xxi, 1893. 



* Pfeiffer, loc. cit. ' Pfeiffer, Zeit. f. Hyg., xiii, 1892, 



^Wollstein, Jour. Exp. Med., viii, 1906. 



