630 COMMUNICABLE DISEASES OF LABORATORY ANIMALS 



secondary foci in the internal organs and the micro-organisms which have been iso- 

 lated resemble those generally attributed to B. necroseos or Schmorl's bacillus. How- 

 ever, some of the strains differ in the essential characteristics as referred to in the 

 description given by Cesari and Alleaux,' Jensen,^ and others. The writer has seen 

 sporadic cases of necrosis-bacillus infection in the buccal cavity of rabbits with in- 

 jured gums due to the prolonged application of unsuitable gags. In several trials the 

 infected sloughs were rubbed on the nostrils and gums of healthy rabbits with en- 

 tirely negative results. It is questionable whether or not the bacillus is the causative 

 agent of epidemics or sporadic cases with which it has been associated. 



MISCELLANEOUS INFECTIONS 



A number of years ago the discovery of a spontaneous venereal spirochetosis of the 

 rabbit which affected, according to Arzt and Kerl,^ 26.9 per cent of the animals of a 

 rabbitry, attracted considerable attention. It was disconcerting to find that a 

 spirochete resembled Treponema pallidum sufficiently closely to render a differential 

 diagnosis difficult and to render doubtful a great mass of experimental work on the 

 transmission of human syphilis to the rabbit. Fortunately, the many investigations 

 in Europe (see literature cited by M. Zuelzer)'' and in the United States by Noguchi^ 

 and by Warthin^ and his associates show that the invasion of Treponema cuniculi 

 produces a superficial, condylomatous lesion, transmissible by contact, coitus, and 

 inoculation, but no colonization in the internal organs. Rabbits which have re- 

 covered from the infection are still susceptible to inoculations with Treponema palli- 

 dum. Salvarsan preparations (neosalvarsan 0.25-0.35 gm. prodosi) have striking 

 curative properties. 



The recent controversial literature on experimental encephalitis in rabbits fur- 

 nishes an excellent example of the many obstacles which still entangle the workers who 

 are not acquainted with the spontaneous diseases of laboratory animals. Again it is 

 shown that a latent, widespread parasite affecting a variety of species may be re- 

 sponsible for misleading conclusions. The accidental discovery of Encephalitozoon 

 cuniculi must be credited to Bull (191 7)' and Ten Broeck* who saw it in sections of 

 the brain and the kidneys of rabbits used for experimental purposes. Wright and 

 Craighead'' observed in 1922 a form of paralysis in young rabbits and found that it 

 was due to an organism which they thought might be an intermediate stage in the 

 life-history of some protozoan parasite. It was noticed in most of the tissues of the 

 body, but it was seen especially in the kidneys, urine, and the nerve cells of the 



' Cesari, E., and Alleaux, V.: Ann. de Vlnst. Pasteur, 26, 625. 1912. 



-Jensen, C. O.: Handb. d. path. Mikroorg. (ist ed.), 2,693. IQOS- 



3 Arzt, L., and Kerl, W.: Wien. klin. Wchnschr., 27, 1053. igi^; Dermal. Wchnschr., 71, 1047. 

 1920. 



■•Zuelzer, M.: Prowazek's Handb. d. path. Prolozoen, Lief. ii,p. 1784. 1924. 



5 Noguchi, H.: /. Exper. Med., 35, 391. 1922; J. A.M. A., 77, 2052. 1921. .\lso cf. chap, .xxxvi 

 by Dr. Noguchi in this volume. 



''VVarthin, A. S., Buflinglon, E., and Wanslrom, R. C: J . Infect. Dis., 32, 315. 1923. 



7 Bull, C. G.: /. E.yper. Med., 15, 557. 1917. 



'See Smith, T., and Florence, L.: ibid., 41, 25. 1925. 

 ■ 'Wright, J. H., and Craighead, E. M.: ibid., 36, 135. 1922. 



