390 BIOLOGY OF THE LABORATORY MOUSE 



could be reproduced experimentally in young mice, but not in adult animals 

 unless massive doses were employed. Infection by contact was possible. 

 Virus or parasitic agents were not demonstrable. Fecal carriers appeared 

 probable, since the organism was found in the intestinal contents of the 

 recovered mice. 



The organism differed from known Salmonella species in the formation 

 of indol, the fermentation of carbohydrates, and its specific serological 

 reactions, and was tentatively classified in the Asiaticus group of the genus 



(44). 



Antoine and Regnier (lo) have reported an epidemic of a septicemic 



Salmonella infection which was unusual because of the presence of ocular 

 lesions. Following a conjunctivitis, the ocular and periocular tissues 

 became involved, producing a characteristic facies (ram's face — "Museau 

 de belier")- Hemorrhagic visceral lesions were present and both types of 

 lesions were reproduced experimentally. The organism was not further 

 identified. 



Prevention. — Attempts to evaluate immunization against this disease 

 have chiefly been carried out in conjunction with studies of experimental 

 epidemics in mice (Neufeld, Topley, Webster, and their coworkers). In 

 general, it may be said that the use of killed vaccines (286, 315, 289) or 

 bacteriophage (290, 288, 186) is not effective in preventing fatal infection 

 or spread of the disease when vaccinated and normal mice are in close 

 contact. In many cases the chief evidence of increased resistance is merely 

 a prolongation of life (182, 140, 107). The vaccination itself may be fatal 

 (336). Furthermore, the presence of agglutinating antibodies in sera of 

 recovered or vaccinated mice is not necessarily correlated with resistance 

 (308, 289). Surviving animals may, however, be more resistant to a 

 subsequent inoculation by virtue of specific (289) or nonspecific (308) 

 protective factors. 



Vaccination may be of some value in preventing epidemic spread in a 

 valuable animal stock which is already infected (159, 205, 105). In the 

 Rockefeller Institute's cancer stock, the survivors of two epidemics of 

 mouse typhoid due to 5. enteritidis and S. typhimurium {B. aertrycke) were 

 vaccinated with a killed suspension of both organisms. No further out- 

 breaks occurred, although a high fecal carrier rate persisted for 5. enteritidis 

 and a low rate for S. typhimurium. It is possible that vaccination con- 

 tributed, in part at least, to the disappearance of epidemic outbreaks. A 

 similar contaminated stock would be wholly unsatisfactory, however, for 

 such experimental studies as protection tests and virulence determinations. 



