370 TYPHOID FEVER 



development of illness. These latter would be accounted for by 

 a low degree of susceptibility on the part of the individual or to 

 a want of pathogenicity in the cultures. 



There is evidence that certain individuals are relatively in- 

 susceptible to typhoid fever. The cases of the occurrence of 

 typhoid bacilli in the healthy intestine support this view, and it 

 has been further shown that during an epidemic certain persons' 

 may suffer from slight intestinal symptoms with typhoid bacilli 

 in the fasces without the disease going through its usual course. 

 The so-called " ambulatory " cases of typhoid fever form a link 

 between these mild infections and fully developed typhoid fever. 

 Typhoid Carriers. — In the great majority of cases of typhoid 

 fever, the bacilli disappear from the faeces within from two to 

 ten weeks of convalescence, but in a certain proportion of cases, 

 probably about 2 to 5 per cent., evidence is found of the per- 

 sistence of the bacilli for many months, and in certain cases 

 their existence has been demonstrated even thirty and, it may 

 be, fifty years after the attack of illness. Carriers have been 

 arbitrarily classified as " temporary" (i.e., those excreting bacilli up 

 to a year after an attack of fever) and as " chronic " (those where 

 this period is exceeded), but the distinction is unimportant. It 

 may be said that the majority of carriers to whom outbreaks 

 have been traced are women. Persons in whom the carrier 

 phenomenon is present are a constant danger to those around 

 them, as the infectivity of the bacilli ^frequently remains, aDd 

 during recent years the importance of such carriers has been 

 recognised as explaining many Outbreaks of the disease. The 

 cases traceable to such an origin are of the type usually classed 

 as sporadic. They arise amongst persons associated with carriers, 

 especially when the latter are concerned in the preparation of 

 food. From time to time, however, larger epidemics have 

 arisen from a carrier having contaminated a milk supply in a 

 dairy. The site of the multiplication of the bacteria in a great 

 many of these carriers is probably the gall-bladder (see p. 367). 

 As has been stated, the typhoid bacilli may persist there for 

 many years, often giving rise to gallstones. The fact that 

 women appear to be more liable to gallstones than men con- 

 stitutes a serious factor in relation to the problem of the typhoid 

 carrier, as women are more concerned in the preparation of food. 

 An additional danger lies in the fact that carriers usually appear 

 to be in perfect health or may only suffer from slight, and to 

 them unimportant, pains in the region of the gall-bladder, it 

 being well known that in only a proportion of patients suffering 

 from gallstones do severe symptoms arise. An additional factor 



