792 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC ANIMALS 



to be three hundred thousand times more resistant to tetanus toxin 

 than the horse. Reptiles and amphibiftns are practically immune to 

 very large doses when kept at low -temperature. 



Natural infections probably do not occur without the presence of 

 other microorganisms. The bacillus and its associated material gains 

 entrance through some break in the tissues. The organism is prac^ 

 tically confined to the site of inoculation, but it is sometimes found in 

 the blood and internal organs after death. 



Against toxin-freed cultures phagocytosis is probably the process 

 which overcomes infection. The toxin is highly antigenic and animals 

 can be immunized against it in a manner similar to that for diphtheria 

 toxin. 



While direct infection of one person from another has occurred, 

 cases of human tetanus are very rarely responsible for others. 



Horses are chiefly responsible for its distribution, the tetanus 

 bacillus being common in manure, which accounts for the occurrence of 

 tetanus in soil-contaminated injuries. 



Cattle probably are also carriers of the bacillus. Tetanus antitoxin 

 as a cure has been a keen disappointment, especially if symptoms have 

 fully developed after a short incubation period. Very large dosage, 

 however, may have, the desired effect. In prophylaxis the antitoxic 

 serum is widely and successfully used in all suspicious cases, and in 

 Fourth of July injuries in particular. 



Typhoid, Fever* 



Bacillus typhosus 



Typhoid fever is one of the most widespread of bacterial diseases 

 and is foiind endemic in practically all the countries of the world. 

 Epidemics frequently occur because of the infection of some local 

 public utihty related to food or drink, particularly water or mil k. 



Typhoid fever occurs naturally only in maij. Intraperitoneal inocu- 

 lation of susceptible animals may result in death with acute peritonitis, 

 but lesions are in no way specific and can be produced by the colon 

 bacillus. 



* Prepared by Edward Pidlar. 



