678 DISEASES OF UNKNOWN ETIOLOGY 



the cultivation of a Gram-positive pleomorphic, anaerobic bacillus from 

 the blood of six vases of Brill's disease and from an equal number of 

 typhus cases. Complement fixation was obtained, when this organism 

 was used as antigen, with the blood of typhus fever cases and it seems 

 not unhkely, at the present time, that Plotz's bacillus may prove to be 

 the etiological factor of typhus. His detailed report has not yet ap- 

 peared at the present writing. Cultivation experiments by other 

 writers have also been negative and the etiological significance of the 

 organisms of Ricketts and Wilder is very doubtful. 



Filtration experiments carried out by Ricketts and Wilder and by 

 Anderson and Goldberger at first indicated that the virus did not go 

 through Berkefeld filters. Nicolle, Conor, and Conseil ^ noticed that 

 inoculation with the filtered blood rendered monkeys refractory, an 

 observation later recorded also by Wilder and Ricketts. Goldberger 

 and Anderson report similar results. By the French investigators this 

 fact has been interpreted as indicating that the virus is filtrable, and 

 Goldberger and Anderson admit this as a possibility. It is Hkely there- 

 fore but not proven that the virus of typhus fever may have a filtrable 

 stage. 



By the work of Nicolle and his associates, and of Ricketts and 

 Wilder,^ also of Anderson and Goldberger,^ it has been shown that the 

 virus can be transmitted from human being to human being by the 

 bites of the body louse (pediculus vestimenti) ; the flea and the bed bug 

 apparently do not transmit the disease. The head louse (pediculus 

 capitis) may possibly transmit it. 



FOOT-AND-MOUTH DISEASE 



This malady occurs chiefly in cattle, sheep, and goats, more rarely 

 in other domestic animals. It is characterized by the appearance of a 

 vesicular eruption localized upon the mucosa of the mouth and upon the 

 delicate skin between the hoofs. In the females similar eruptions may 

 appear upon the udders. With the onset of the eruption theye may be 

 increased temperature, refusal of food, and general depression. Usually 

 the disease is mild; the vesicles go on to the formation of small ulcers 

 and pustules, and gradually heal with a disappearance of systemic 



' Nicolle, Conor, et Conseil, Compt. rend. Acad. d. Sc, Sept. 18, 1911. 



2 Wilder, Jour. Inf. Dis., July, 1911, p. 9. 



3 Goldberger and Anderson, Pub. Health Report, Wash., March, 1912; ibid.. 

 May 31, 1912. 



