230 BACILLI OF THE HEMORRHAGIC SEPTICEMIA GROUP 



The organism is pathogenic for guinea-pigs, rabbits, mice, dogs, 

 cats, swine, sheep, donkeys, and horses. Whether it is pathogenic 

 for cattle is doubtful. 



Natural Infection. In the horse, natural infection is spread by the 

 secretion from the diseased mucous membranes and lungs and through 

 the feces. These secretions and excretions are particularly infectious 

 while the disease is at its height, but they may also spread the con- 

 tagium for a long time after the affection has run its course. After 

 infection of a previously healthy animal the bacilli multiply rapidly 

 in the mucous membranes and invade the lymph and blood circula- 

 tions, producing in very violent rapidly fatal cases the picture of 

 typical hemorrhagic septicemia. 



Hutyra has confirmed the observations of Lignire, identifying the 

 Bacillus equisepticus as the cause of horse influenza, or pink-eye, but 

 other authors still consider the etiology unsettled, and doubt whether 

 this organism is the actual cause. 



BACILLUS OF DOG TYPHUS. 



An acute, epidemic disease of dogs, characterized by a violent 

 gastro-enteritis with ulcerative stomatitis was first described in 1850 

 by Hofer under the name of "Hundetyphus," dog typhus, and later 

 under the name gastro-enteritis hemorrhagica. During the last two 

 decades several larger epidemics have been described in Germany 

 and other parts of Europe. Ligniere claims that the disease is due 

 to a bacillus of the hemorrhagic septicemia group. He describes the 

 organisms as having the general characteristics of the group, but that 

 it is larger when it first occurs in the dog and only becomes smaller 

 after having passed through several guinea-pigs. It grows on culture 

 media much like the other members of the group. Ligniere's claim 

 has not been confirmed. Hutyra states that he has examined bacte- 

 riologically a number of cases, but has not obtained Ligniere's bacillus 

 but a bacillus of the colon group and another virulent bacillus of the 

 proteus group. 



BACILLUS PESTIS. 



Occurrence and Historical. The Bacillus pestis, or the bacillus of 

 bubonic plague, is the most extensively studied, and now best-known 

 organism of the group of bacilli of hemorrhagic septicemias. It is the 

 cause of the most dreaded human scourge, bubonic plague, the "Great 

 Black Death" of the Middle Ages, which is estimated to have carried 

 away, within a space of three years, twenty-five millions of people in 

 Europe during the fourteenth century. In the last century the disease 

 seemed to have almost if not completely died out, but toward the close 

 a great pandemic broke out in India and China. It spread to various 



