INFLUENZA 57 



form very minute translucent colonies, much like those of the 

 pneumococci, and cultures have a great tendency to die out. 



The vaccine treatment of influenza or nasal catarrh due to this 

 organism is not very satisfactory. 



The M. catarrhalis (Plate III., Fig. 5), the next most frequent 

 cause of clinical influenza, is a diplococcus which does not stain by 

 Gram, and which has a considerable amount of resemblance to 

 the other two non-Gram-staining diplococci, the gonococcus and the 

 meningococcus. It occurs in vast numbers in the sputum and 

 nasal mucus of influenza, in the nasal mucus of a " common cold," 

 and is a common cause of bronchitis of ordinary type. It is also 

 an occasional cause of sore throat, and is not infrequently met 

 with in the examination of supposed cases of diphtheria. The 

 resemblance to the two other organisms named arises from the 

 fact that it is frequently intracellular. There is not usually any 

 difficulty in distinguishing between the three, owing to the difference 

 in their habitat — the gonococcus affecting the mucous membrane 

 of the urethra or cervix, the meningococcus the meninges, and 

 the M. catarrhalis the nose, mouth, and respiratory passages. 

 There are minute morphological differences between the three, 

 and an expert can usually identify them in film preparations 

 from the body, but where there is any question of the nature of the 

 organism present cultures ought to be made. The M. catarrhalis 

 is the only one of the three which will grow on gelatin at the 

 room temperature. 



Vaccine treatment is fairly satisfactory, the disease often clearing 

 up quickly after two or three doses, and the patient seems to show 

 a certain amount of immunity for some months after. The dose 

 should be loo to 500 millions. 



B. septus is another frequent cause of catarrh of a form which 

 may fairly be grouped under the clinical term influenza. It is 

 a short. Gram-positive bacillus which is frequently mistaken for 

 the pneumococcus, but has no capsule. In young cultures it is 

 a short oval rod ; in older ones there is an unstained band (from 

 which it derives its name) across the centre of the rod. On the 

 whole, vaccine treatment does not seem very satisfactory. The 

 doses should be 100 to 250 millions. Sometimes the vaccine is 

 extremely irritating, so that it is perhaps wiser to begin with 

 not more than 50 millions. 



