650 PATHOGENIC MICROORGANISMS 



twenty-five days. Gay and Claypole 19 have been able to produce 

 the carrier state in rabbits with great regularity by growing the typhoid 

 cultures used for inoculation upon agar containing 10 per cent defib- 

 rinated rabbit's blood. Such cultures are not as readily agglutinated 

 by immune serum as are those grown on plain agar, and it may well be 

 that they have acquired a certain degree of resistance to the serum 

 antibodies which renders them more competent to survive in the body 

 of the rabbit. Gay has used rabbits inoculated with such cultures for 

 the determination of the efficacy of his sensitized vaccines. 



Typical typhoid fever simulating the disease in man has not been 

 produced in any animals except in chimpanzees, by Metchnikoff and 

 Besredka, 20 who produced it in connection with their experiments on 

 protective vaccination. They produced a disease almost identical 

 with human typhoid by feeding cultures to chimpanzees. 



TYPHOID FEVER IN MAN. It is not within the province of a book of 

 this kind to give an accurate clinical description of the disease as it 

 occurs in man in all its details. The disease is one in which a wide 

 range of variation may occur, and in which complications are various 

 and manifold. We will, therefore, give only a brief account of the 

 infection as it is relevant to bacteriological work. The organisms enter 

 by mouth, with food, water or contact with fingers, direct or indirect, 

 as described in the epidemiological section. Subsequently, the organ- 

 isms, which pass through the stomach uninjured, multiply in the intes- 

 tine, but cause no symptoms for anywhere from seven to fourteen 

 days. During this time they probably begin to proliferate partly 

 within the mucous membrane of the bowel, although there is little 

 definite knowledge concerning this. The symptoms of the disease 

 begin insidiously by gradual malaise, headache, loss of appetite, sleep- 

 lessness, and during the first week of the actual signs of infection, the 

 organisms have probably penetrated or are penetrating into the lym- 

 phatics. At this time there is a swelling of the lymphoid nodules of the 

 intestine and Peyer's patches, and there is a moderate catarrhal inflam- 

 mation of the mucous membrane. At this time too the bacilli enter the 

 blood stream and can be found in blood culture. 



Though formerly regarded as primarily an intestinal disease, the 

 disease is in truth at this time a bacteriemia, and it is not impossible 

 that the intestinal lesions are as much due to the action of toxic products 

 which are excreted in part through the intestinal wall, as they are due 



19 Gay and Claypole, Arch, of Inf. Med., Dec., 1913. 

 ' 20 Metchnikoff and Besredka, Ann. de Flnst. Past., 1911, 25, 193. 



