DYSENTERY SERUM 449 



at a later stage (after two to three days) the other 

 organisms in the bowel multiply to such an extent that 

 isolation may become difficult. The material should be 

 quite fresh, and anilin-dye media are better avoided. 

 " Carriers " occur and help to spread the disease, which 

 may be conveyed by infected water and food and by flies. 



Toxins. The filtrate of dysentery cultures (four to six 

 weeks old), particularly the Shiga strain, in a somewhat 

 highly alkaline broth (broth just alkaline to litmus -f- 

 7 c.c. normal NaOH per litre) is markedly toxic, 0-1 c.c. 

 being a fatal dose for a large rabbit. 1 



Anti-serum and vaccine. The serum of horses immu- 

 nised with the toxin, or with dead and then with living 

 cultures, possesses marked antitoxic properties, and the 

 use of this antitoxic serum has been successful in cases 

 of acute bacillary dysentery. Shiga obtained a reduction 

 in mortality of from 22 to 7 per cent, by the use of serum 

 in a severe epidemic, and striking results were obtained 

 by Ruffer and Willmore 2 in Egypt and by Bahr in Fiji. 

 It is necessary, however, to employ a serum prepared with 

 the particular strains of the disease. 



When the disease has become chronic the use of a . 

 vaccine, consisting of a culture sterilised by heat, is some- 

 times beneficial. Dysentery vaccines for prophylaxis are 

 now being tried. 



Asylums dysentery and summer diarrhoea of infants. 

 Both in America and in England some cases of summer 

 diarrhoea of infants are found to be associated with the 

 B. dysenterice. The asylums or institutional dysentery, 

 or ulcerative colitis, is also due to this organism, and in 

 this country is almost invariably due to the Flexner type. 



Other organisms have been described as being capable of 

 inducing diarrhoea or dysentery, such as the Schmitz and Gettings' 



1 Todd, Journ. of Hygiene, vol. iv, 1904, p. 480 (Bibliog.). 



2 Brit. Med. Journ., 1909, vol. ii, p. 862, and 1910, vol. ii, p. 1519. 

 M.B. 29 



