K. F. MEYER 613 



roughening of the fur, emaciation, and weakness. Diarrhea is noted only in experimental 

 animals fed with highly toxic broth cultures. The autopsy findings vary considerably. The 

 most constant lesions are found in the spleen and liver. The spleen is enlarged and congested 

 (4§ cm. long by 2 cm. wide), soft, occasionally covered by a plastic exudate, and studded 

 throughout with minute foci or large yellowish nodules. Grayish foci or necroses similar 

 to those seen in typhoid fever are present in the liver; quite often the gall-bladder 

 contains a thin, purulent fluid. The intestines are injected and the swollen, grayish Peyer's 

 patches occasionally stippled with yellowish nodules are quite prominent. The mesenteric 

 lymph nodes are always enlarged, medullar}', and sometimes transformed into cheesy 

 abscesses. Effusion in the pleural cavities, congestion of the lungs, patchy areas of consolida- 

 tion or yellowish foci, or double lobar pneumonia are constant in certain spontaneous out- 

 breaks. The involvement of the uterus (purulent endometritis) is frequently reported (in- 

 fectious endometritis, Carter's bacillus; see Smith and Reagh).^ 



Without a thorough bacteriological study a differential diagnosis between a paratyphoid 

 and B. pscudotuboxidosis or pscudopestis infection is frequently impossible. A number of pro- 

 cedures have been suggested to detect latent infections and carriers; although specific agglu- 

 tinins can be demonstrated in the blood serum of the animals which present lesions at 

 autopsy (Smith and Nelson^ and others), the tests are not practical. Shaw and Meyer^ have 

 therefore used with considerable success the intracutaneous hypersensitiveness tests witn pure 

 bacterial proteins. Examinations of the feces for paratyphoid bacilli are unreliable. 



Since the mortality may vary from 4 to 70 per cent of a laboratory stock (Petrie 

 and O'Brien^ lost 479 of 500 animals, and Howell and Schultz^ estimated their losses 

 at 500 and Kit tier'' at 395 guinea pigs; Nelson and Smith^ report a mortality of 4 per 

 cent in one month), repeated attempts have been made to control this malady by 

 immunization. Nichols and StimmeP obtained experimentally some protection 

 against a highly virulent acrtrycke strain, and Howell and Schultz^ apparently con- 

 trolled an epizootic by immunization of the guinea pig stock with a polyvalent sus- 

 pension of the organism. Miiller'' combatted an outbreak with a polyvalent para- 

 typhoid serum. On the other hand, the reports of Steinmetz and Lerche'" and Kittler" 

 confirm the observations of the writer. Neither the use of specific monovalent sera 

 nor various types of vaccines changed the character of an epidemic or protected ex- 

 perimentally a series of guinea pigs subjected repeatedly to heavy infections per os 

 from acquiring a chronic carrier state. In case paratyphoid has broken out in a 

 guinea pig population it is much more economical to adopt strict measures of isola- 

 tion, detection of the latent infections by means of skin tests, and the destruction of 

 the reactors than to trust the efi&cacy of immunization. The laboratory stock can be 

 kept free from the disease by judicious selection and purchase of breeding animals 



' Smith, T., and Reagh, .\. L.: J . Med. Research, 4, 270. 1903. 

 ' Smith, T., and Nelson, J. B.: loc. cit. 



i Shaw, E. B., and Meyer, K. F.: unpublished manuscript. Master's thesis. University of CaH- 

 fornia, 1920. 



* Petrie, G. F., and O'Brien, R. A.: loc. oil. ^ Kittler, K.: loc. cit. 



5 Howell, K. M., and Schultz, O. T.: loc. cit. " Nelson, J. B., and Smith, T.: loc. cit. 



8 Nichols, H. J., and Stimmel, C. O.: J. Expcr. Med., 38, 283. 1923. 

 'Miiller: Ztschr.f. Veterindrk., 29, 115. 1917. 

 " Steinmetz, M., and Lerche, P.: loc. cit. " Kittler, K.: loc. cit. 



