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VETERINARY BACTERIOLOGY 



Transmission. Typhoid fever is contracted from contaminated 

 drinking-water, milk and other foods, and by contact, the fre- 

 quency being in about the order named. Flies probably are com- 

 monly instrumental in carrying the organism from dejecta of 

 typhoid-fever patients to food materials. The term bacillus 

 carrier, or germ-carrier, is used to designate an individual who still 

 harbors a pathogenic organism in the body after convalescence. 

 Such germ-carriers are particularly dangerous, as they may give 

 rise to an epidemic that is almost impossible to trace to its source. 

 The danger of milk infection is probably the greatest from in- 

 dividuals that are employed in dairies. Several epidemics have 

 been traced to this origin. 



Bacillus dysenteriae 



Synonyms. Bacillus of Shiga; bacillus of Flexner. 

 Disease Produced. Bacillary dysentery. 

 Shiga, in 1898, discovered in the feces of patients suffering from 

 dysentery a bacillus which he believed to be the specific cause of 



the disease. Previous to this 

 i had been shown that amebae 

 may cause dysentery, and it 

 was when examining stools for 

 these protozoa that Shiga dis- 

 covered this organism. In 1900 

 Flexner published the results of 

 work in Manila and described 

 another type of organism. 

 Since that time many epi- 

 demics have been studied, and 

 it is generally believed that 

 the type described by Shiga is 

 the more common, but that the 

 bacillus of Flexner occurs in a certain proportion of the out- 

 breaks, more particularly in the tropical countries. Other 

 authors, Hiss in particular, have differentiated even more 

 groups. 



Morphology. B. dysenterice and B. typhosus are practically 

 indistinguishable under the microscope in stained mounts. The 



Fig. 118. Bacillus dysenteries (Kolle 

 and Wassermann). 



