350 AGEICULTUEAL AND INDUSTRIAL BACTEEIOLOGT 



cimiculicida. Hemorrhagic septieemia has been described in 

 the sheep and the horse, likewise an infectious pneumonia 

 of goats, a pasteurellosis of buffalo, and pasteurelloses of 

 many species of birds, including geese and ducks. 



Pasteurella pestis 



Synonyms. — Bacterium pestis, Bacillus pestis huhonicce. 



This organism is the specific cause of the disease plague 

 in man and in rodents. It was discovered independently by 

 Yersin and by Kitasato in 1894. The disease is one which 

 is apparently endemic in certain parts of Asia, particularly 

 in northern and western China, and has at various times 

 spread over the entire civilized world. Bubonic plague has 

 been reported as present from the ports of entry of prac- 

 tically every continent in recent years. 



Pasteurella pestis resembles closely the other organisms 

 belonging to this group. It grows rather readily upon cul- 

 ture media. 



The disease plague in man is usually contracted from dis- 

 eased rodents, particularly rats. It seems to be conclusively 

 demonstrated that the disease is primarily one of rodents 

 transmitted to man by means of the rat flea. If it attacks 

 man, it may develop in one of the three forms. Bubonic 

 plague results from cutaneous infection as a result of a 

 bite from a flea or of scratching the dejecta of the flea into 

 the skin. The organism enters the lymph channels and 

 causes ulceration of the lymph nodes, that is, it forms so- 

 called buboes. These may ultimately heal and the patient 

 recover; more frequently, however, the organism finally 

 invades the blood stream and the patient dies from the 

 resultant septicemia. When the organism is more virulent 

 it may enter the blood stream promptly after entrance into 

 the body and produce a typical hemorrhagic septicemia. 

 Hemorrhages develop under the skin and large areas 

 become discolored. This is the so-called "black death" 



