460 DIPHTHERIA, SCARLET FEVER, AND TETANUS 



ance. Under favorable conditions these spores remain virulent for 

 years. The tetanus bacillus was first discovered bvNicolaier in 1884 

 and cultivated by Kitasato in 1889. Shortly after this, Von Beh- 

 ring succeeded in producing an effective tetanus antitoxin. 



Occurrence. Tetanus bacilli are found in damp soil and in dust, 

 especially around stables, in manure, and in dust of the house and 

 street. They are so plentiful in the intestinal contents of horses 

 and cows, whose wastes are commonly employed to fertilize gar- 

 dens, that tetanus is sometimes regarded as a disease contracted 

 indirectly from these animals. Other herbivorous animals also 

 harbor the germ. The bacilli are likely to be found on rusty nails 

 or implements which have been in contact with the ground, on 

 dirty splinters, and on gunshot. 



Tetanus bacilli are anaerobic (cannot grow when exposed to 

 the air) ; therefore, deep wounds are most favorable for their de- 

 velopment. They are unusual in that they do not grow on healthy 

 living tissues, but on cells which have been torn and killed. Badly 

 lacerated wounds present a more favorable surface for the growth 

 of tetanus than do those made bv verv keen clean instruments. 



How tetanus enters the body. The bacilli gain entrance to 

 the body through wounds varying in size from a needle prick to 

 an operation wound. Being anaerobic, the organisms infect 

 deep lacerated wounds such as those made on the hand by the 

 accidental explosion of a toy pistol or wounds on the feet made by 

 the deep puncture of a rusty nail. Rusty nails themselves never 

 produce lockjaw, but the bacteria are frequently held in the rough 

 spots of the rust and consequently enter the body if the nail 

 happens to puncture the flesh. Occasionally, the disease occurs 

 without any evident wound. In cases like this, the bacteria have 

 made an entrance through some unnoticed abrasion of the skin or 

 the mucous membrane. 



Tetanus has been observed not only in man, but in domesticated 

 animals such as the horse, sheep, dog, cow, and pig. 



