MICROBIAL DISEASES OF MAN AND ANIMALS. 619 



^ 



All plain cases of glanders in domestic animals should be promptly 

 destroyed. Exposed horses should be tested with mallein. Those that 

 react should be destroyed or quarantined, and contaminated premises 

 properly disinfected. 



INFLUENZA.* 



Bacterium influenza. 



The natural disease appears to be limited to man. The incubation 

 period is very uncertain probably very variable. 



While the clinical manifestations of infection with Bad. influenza are 

 variable the ordinary form begins with sudden severe headache accom- 

 panied by great prostration, pains and aches in the back and bones, and a 

 rapid rise of temperature. The fever lasts from three to five days and 

 leaves the patient extremely weak, and depressed in both mind and body. 



Pfeiffer in 1892 described a bacterium which occurred in large numbers 

 in the purulent bronchial secretion expectorated by influenza patients. 

 The causal relationship has been quite definitely established. 



An examination of the sputum furnishes good presumptive evidence, 

 but cultivation is necessary for positive diagnosis. 



The purulent material is streaked out in a drop of sterile blood upon 

 an agar plate. 



Agglutination and complement fixation tests are valuable means for 

 identification. 



In pure cultures the bacterium is o.2/* to 0.3/1 wide by 0.5^ long with occasional 

 threads up to zfj. in length. The ends of the rod are rounded. The arrangement is 

 usually single, occasionally in pairs end to end and rarely in chains. The bacterium is 

 non-motile and does not show capsules or spores. It does not stain readily with 

 ordinary aniline dyes. It is Gram-negative. Polar staining is shown sometimes. 

 The temperature range of the influenza bacterium is about 26 to 41. It is aerobic. 

 It grows on artificial media only in the presence of blood pigment. On plain agar, 

 glycerin agar, or blood serum with a thin layer of rabbit or human blood the colonies 

 in twenty-four hours are very small, round and transparent, and remain discrete 

 unless very thickly sown. The center of older colonies may acquire a yellow-brown 

 color. In blood broth growth occurs quite readily if the medium is used in thin layers. 

 It shows very much less resistance than the majority of non-spore-bearing bacteria. 

 It is destroyed at 60 within about one minute. It is especially sensitive to drying. 



The bacterium gains entrance through the mouth and nose and finds 

 suitable soil in the mucous membrane of the respiratory passage. The 



*Prepared by Edward Fidlar. 



