SPIRILLUM MINUS 



925 





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Spirillum minus 



Sometimes referred to as SpirochcBta morsus murin. Described by Futaki and his 

 colleagues (1916, 1917) as the cause of rat-bite fever in man. According to Robertson 

 (1924), it is a spirillum and not a spirochsete, and its correct name is Spirillum minus. 

 Appears to be a natural parasite of rats, which act as healthy carriers of the organism. 

 Morphologically the spirillum is short, rather thick, and has tapermg ends, provided 

 with one or more flagella. It is 2-5 // long, motile, and has regular rigid spirals, each 

 of which is about I fi in length. The movements are rapid— like those of a vibrio. It 

 is readily stained by ordmary aniline 

 dyes, such as Loeffler's methylene blue, 

 and by Giemsa. Cultures may be 

 obtained in Shimamine's medium, but 

 successive transfers have not been 

 successful. The organism gives rise to 

 one type of rat-bite fever in man. 

 Intraperitoneal inoculation of infective 

 human material into mice is followed 

 by no clinical evidence of disease, but 

 spirilla appear in the blood after 5 to 

 14 days. They are scarce at first, but 

 later they increase, though they never 

 become numerous ; it is uncommon 

 to find two organisms in the same 

 field (Theiler 1926). They persist in- 

 definitely, though only in small num- 

 bers. Rats behave like mice, but the 

 number of spirilla in the blood is 

 fewer. Intraperitoneal inoculation of 

 guinea-pigs produces a febrile disease. 

 After an incubation period of 6 to 15 

 days spirilla appear in small numbers 

 in the blood, and pyrexia sets in 



accompanied by enlargement of the lymph glands. There may be a marked inflam- 

 mation of the subcutaneous tissue in the ano-genital region, involving the scrotal 

 sacs, perianal tissue, and prepuce in males and the labia and perianal tissue in 

 females. Later, after 3 or 4 weeks, alopecia, ulceration of the skin, and chronic conjunc- 

 tivitis and keratitis may occur. The disease is generally chronic, lasting from about 2 

 to 4 months, but sometimes death occurs in the first 5 weeks (Ishiwara et al. 1917). Spirilla 

 can be demonstrated in the blood, lymph glands, spleen, kidney, adrenal, and subcutaneous 

 tissue. In Robertson's (1924) experience spirilla were never demonstrable in the blood, 

 even by mouse inoculation, nor did any of the guinea-pigs die. Rabbits may be infected, 

 but are less suitable for diagnostic purposes than mice or guinea-pigs. Monkeys are also 

 susceptible (Inada et al. 1916). 



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Fig. 220. — Spirillum minus. 



In film of blood of experimentally infected mouse. 

 Giemsa. (x 1000). [From specimen kindly sup- 

 plied by the late Prof. J. G. Thomson.] 



REFERENCES 



Aksjanzew-Malkin, S. (1933) Zbl. Bakt., 129, 405. 



Babudieri, B. (1938) Polidinico, Sez. prat., 45, 1774; (1939) Riv. Parassitol, 3, 93. 



Baermann, G. and Zuelzer, M. (1927) Klin. Wschr., 6, 979 ; (1928) Zbl. Bakt., 105, 345, 



Bauer, J. H. (1927) Amer. J. trop. Med., 7, 177. 



Bayon, H. (1913) Brit. med. J., ii. 1159. 



Bertaeelli, E. (1906) Zbl. Bakt., 41, 320 ; (1907) Ibid., 43, 238, 448 ; (1908) Ibid., 46, 51. 



Bessemans, A. and Potter, F. de. (1930) G.R.Soc. Biol, 104, 818; (1931) /6icZ.,107,279. 



BoAK, R. A., Carpenter, C. M., and Warren, S. L. (1932) J. exp. Med., 56, 725. 



Brown, H. C. and Davis, L. J. (1927) Brit. J. exp. Path., 8, 397. 



