378 TYPHOID FEVER 



great prominence from the fact that they have constituted a 

 predominant group amongst intestinal infections as a whole. 

 Clinically they generally have the character of a mild typhoid 

 infection, often characterised merely by a transient illness, and 

 the mortality in such cases does not amount to more than 4 

 per cent. Pathologically the lesions are those of typhoid fever 

 with or without, ulceration, but there seems to be a greater 

 tendency to diffuse follicular inflammations and infections of the 

 large intestine and of the appendix and to the occurrence of 

 peritonitis without perforation and of suppuration in, e.g., the 

 spleen, brain, kidney, lymphatic glands, etc. It has been 

 suggested that initially the old term " enteric fever " or 

 " enterica " should be applied to all clinical cases of a typhoid 

 type pending their differentiation into typhoid and paratyphoid 

 fevers by bacteriological methods. It will be seen below that 

 the latter involve a further differentiation between enterica and 

 bacillary dysentery, and that the existence of two varieties of the 

 paratyphoid bacillus must be taken into account. 



The Paratyphoid Bacilli. — These organisms have the general 

 characters of the coli-typhoid group, motility being usually active 

 though the flagella are often few in number. They are non- 

 lactose fermenters and originate acid and gas in glucose, mannite, 

 maltose, dulcite, lsevulose, galactose, sorbite, and arabinose ; 

 they do not ferment raffinose, saccharose, salicin, or inulin. 

 Of these reactions, that towards lactose differentiates them 

 from b. coli, and the production of acid and gas in mannite 

 distinguishes them from b. typhosus and b. dysenteriae. They 

 do not produce indol. Two varieties occur, denominated 

 respectively "paratyphoid A" and "paratyphoid B," the latter 

 being the commoner. The fermentative capacities of these 

 are identical, but A is the less active — gas formation being 

 often scanty and late in appearance. They present slight 

 differences, on ordinary media. On gelatine, agar, and potato 

 A in ' its growth rather resembles b. typhosus, while B is 

 more like b. coli ; in litmus milk A produces, slight permanent 

 acidity, while, in the case of B, after the third day acidity 

 gives place to alkalinity. In the ultimate differentiation of the 

 two types their capacity of originating specific agglutinating 

 sera is of greatest importance. 



The b. paratyphosus was originally isolated from suppurative 

 conditions, e.g., of the genito-urinary tract, of bone, of the 

 thyroid, etc. ; several of these probably followed an intestinal 

 condition — the tendency to suppuration as a complication or 

 sequel to such infection being now recognised. Illnesses of the 



