BEHAVIOR OF BACTERIOPHAGE IN DISEASE 481 



yards. Young adults are the most susceptible, then the old animals; 

 the chicks are in general spared. 



Epizootics of typhosis extend rapidly over large areas; certain De- 

 partments were contaminated throughout in 1919. The estabhshment 

 of a new focus begins by the importation of the organism from an in- 

 fected region, either through the agency of a flock of sheep or herd of 

 cattle, or by horsemen (this last mode of dissemination was particularly 

 frequent during the war; this explains the extension of the disease during 

 the years 1917 and 1918). The disease rages for a few days on a farm, 

 passes to a neighboring farm, and then extends rapidly into the sur- 

 rounding villages. 



The pathogenic bacillus remains alive and virulent during several 

 months in the regions where the infection has been epidemic. In several 

 tests it has been shown that an isolated infected chicken-yard, cleaned 

 and left unoccupied for six to eight months, still contains virulent bacilli, 

 for, when repopulated with chickens from a region free of the disease, 

 the infection breaks out again within a few days among the new 

 occupants. 



Avian typhosis being a disease in general but little known, I have 

 thought it useful to consider it in some detail, since it will allow us the 

 better to understand the facts now to be presented. 



Because of the exceptional severity of the infection in avian typhosis 

 it has been possible to follow only four cases which recovered. In all, 

 the picture has been identical. In the morning the infected chicken 

 remains on the ground, "balled up," the feathers roughened, and with 

 the characteristic diarrhea. The appearance is the same as in the fowls 

 which succumb. At this stage of the infection examination of the feces 

 gives results such as: 



B. gallinarum, present in abundance. 



Intestinal bacteriophage, virulent for B. coli + (in 2 cases) or + + 

 (in 2 cases) ; for B. gallinarum (in the four cases) . The blood culture 

 was positive in the two cases in which it was done; the blood for culture 

 being taken aseptically by puncture of the crest. 



During the course of the day the condition remains the same as that 

 shown by animals which die. This state is prolonged and the next 

 morning the chicken still appears the same. Examination of the feces 

 at this time shows : 



B. gallinarum present in three cases, absent in one. 



Intestinal bacteriophage virulent for B. coli + + + (4 cases); for 

 B. gallinarum ■\- (in 3 cases) +-f+ (in 1 case). Towards noon, in 



