222 THE BACTERIOPHAGE 



that the protection of the body in the case of barbone, a septicemic 

 disease, is assured by the bacteriophage. 



In the buffaloes of a region ravaged by the disease the bacterio- 

 phage preserves for a very long time its virulence for the patho- 

 genic bacterium. This, the following example shows. 



In November, 1919, a localized epizootic of barbone occurred 

 among the buffaloes of the village of Phuoc Thien (Province of 

 Bien Hoa). On a farm having twenty-one buffaloes seven died 

 — two adult animals and five aged from one to two years. The 

 disease died out, or to speak more correctly, after this, two ani- 

 mals recovered one after another. On the 12th of the following 

 April, that is to say, five months later, specimens of the feces of 

 eight of the surviving animals were collected. All contained a 

 bacteriophage active for the bacterium of barbone (six were + + , 

 two were +). 



Two specimens of the mud of a water-hole where the animals 

 were accustomed to remain immersed up to the neck during the 

 hottest hours of the day were also examined. In both a bacterio- 

 phage virulent (++) for the bacterium of barbone was found. 

 The destruction of the pathogenic bacterium in the external 

 medium must often be effected by the bacteriophage, for it is 

 certain that if the bacterium of barbone has once been introduced 

 into a water-hole by a sick animal the bacteriophage present 

 there must destroy it. Furthermore, this fact shows one of the 

 modes of "contagion" of the active bacteriophage. A single 

 buffalo, in the intestine of which the bacteriophage has acquired 

 a virulence for the pathogenic bacterium, is sufficient to "con- 

 taminate" all the herd which frequent the water-hole. Localized 

 epizootics are of short duration, but in spite of this we find that 

 the pathogenic bacterium persists for several months in the ex- 

 ternal world and that their ingestion by buffaloes is frequent, 

 since the virulence of the bacteriophage maintains itself against 

 this bacterium. The repeated ingestion of a bacterium is, as 

 we have seen, essential for the permanence of the virulence of 

 the bacteriophage toward this bacterium. The epizootic dies 

 out, not because of an absence of pathogenic bacteria but because 

 of the presence of a virulent bacteriophage in the intestine of 

 all exposed animals. 



