BACILLUS INFLUENZA 419 



Man. Influenza occurs . pandemically at infrequent intervals: 

 during interpandemic intervals the organism causes somewhat local- 

 ized epidemics of "grippe," and not infrequently appears to be the 

 causative factor in "grippe colds." The bacilli persist in the respira- 

 tory tract as "opportunists" and are frequently detected in the lungs 

 of consumptives. Invasion takes place through the respiratory tract, 

 usually by droplet infection, and frequently spreads by continuity 

 to the lungs, where a purulent broncho- or lobular pneumonia develops 

 in typical cases. Pleurisy is a frequent complication, usually caused 

 by a secondary infection with pneumococci or streptococci. The in- 

 fluenza bacillus rarely causes pleurisy. Enormous numbers of bacilli 

 are coughed up in the sputum. The incubation period is brief, from 

 one to three days as a rule. Influenzal meningitis, 1 pharyngitis and 

 laryngitis 2 and conjunctivitis 3 are not uncommon. The occurrence 

 of influenza bacilli in the blood has been a matter of controversy. 

 Canon, 4 Bruschettini 5 and Ghedini 6 have isolated bacilli from the 

 blood of patients at the height of the disease which they believe to be 

 B. influenzse. Slawyk 7 has reported a case of generalized infection 

 with the influenza bacillus which would appear to confirm these 

 observations. Other investigators have questioned the accuracy of 

 this work and lay stress upon the incomplete diagnosis of the organisms 

 obtained from the patients. The question can not be regarded as 

 definitely settled at the present time. 



Immunity. Attempts to induce immunity in experimental animals 

 have been unsuccessful. Relapses are common in man, and there is 

 no evidence of immunity as the result of recovery from the disease. 



Bacteriological Diagnosis. 1. Sputum raised from the deeper air 

 passages is spread upon slides, air dried, fixed, and stained with dilute 

 carbol-fuchsin. Large numbers of minute organisms colored pink 

 with a tendency toward bipolar staining are suggestive of the influenza 

 bacillus. There is no tendency toward a definite arrangement of the 

 bacilli. They are frequently found in leukocytes. 



2. Cultural. Blood agar plates are made by depositing a generous 

 drop of human, rabbit or pigeon's blood in the centre of an agar plate. 



'Pfuhl, Ztschr. f. Hyg., 1897, xxvi, 112; Frankel. Ztschr. f. Hyg., 1898, xxvii, 329; 

 Jundell, Jahrb. f. Kinderheilk., 1904, lix, 777. 



2 Treitel, Arch. f. Laryngol., 1902, xiii, 147. 



'Pretori, Arch. f. Augenheilk., 1907, Ivii, 97; Possek, Wien. klin. Wchnschr., 1909, 

 No. 10. 



4 Deutsch. med. Wchnschr., 1892, No. 3; Arch. f. Anat. u. Phys., 1893, cxxxi, 401. 



5 Riforma Med., 1893, viii, 783. Centralbl. f. Bakt., Orig., 1907, xliii, 407. 

 7 Ztschr. f. Hyg., 1899, xxxii, 443. 



