108 THE ACUTE SELF-LIMITED INFECTIONS 



wounds about July 4. Every man wounded in the Great 

 War receives antitoxin against tetanus; if the wound be 

 recent a smaller dose is given than when many hours have 

 elapsed. By this means tetanus has been practically eradi- 

 cated from war hospitals caring for wounded. 



BACILLUS TYPHOSUS. 



Typhoid fever or enteric fever is an acute infectious dis- 

 ease caused by the Bacillus typhosis or typhoid bacillus 

 circulating in the blood and settling in the various organs, 

 particularly the lymphatic structures of the small intestines. 



The bacteria enter the body lia the mouth and are able 

 to pass the stomach into the small intestines. Here they 

 are taken up by the lymphatic organs, which immediately 

 begin to swell. This reaction brings more blood to the part 

 and the circulation soon contains the germs. The incuba- 

 tion period is that time elapsing between the introduction 

 of the typhoid bacillus into the alimentary canal and the 

 first positive signs that it has been taken up and disseminated 

 by the blood stream. Then there are gradually increasing 

 fever, malaise, a relatively slow pulse, distention of the 

 abdomen, diarrhea or constipation, rose spots, and other 

 signs of the true infection. The incubation is about two 

 weeks. The bacteria, while not true pus-formers, do cause a 

 breaking down of tissue. This is characteristically seen in 

 the lymphatics of the small intestine called Peyer's plaques. 

 These bodies swell toward the free lumen of the canal, and 

 the center finally softens from the effect of the bacilli. When 

 the softened part separates and is removed, a ragged, punched- 

 out ulceration remains. This ulceration may be progressive 

 and eat into bloodvessels, causing intestinal hemorrhage so 

 common in this disease. If the ulceration be directed out 

 toward the peritoneal surface of the intestine, perforation 

 and peritonitis may ensue. The presence of the typhoid 

 bacilli and their toxins in the organs, notably the spleen, 



