BACILLUS OF TYPHOID FEVER 



407 



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though perfectly well themselves, may be a means of spreading the 

 disease. Such cases have been known to harbor the bacilli for periods 

 as long as several years. 



The examination itself is fraught with difficulties, owing to the pre- 

 ponderating numbers of colon bacilli found in all feces and the difficulty 

 of isolating the typhoid bacilli from such mixtures. 



Reviewing the data collected by a number of investigators, it 

 seems probable that the bacilli do not appear in the stools, at least 

 in numbers sufficient for recognition, much before the middle of the 

 second week, or, in other words, as pointed out by Hiss, about the 



time that the intestinal lesions are well ad- 



vanced and ulceration is occurring. Thus 

 Wiltschour * could not determine their pres- 

 ence before the tenth day; Redtenbacher, 2 

 in reviewing the statistics, states that in a 

 majority of cases the bacilli first appear 

 toward the end of the second week, and 

 Horton-Smith 3 could not find the bacilli be- 

 fore the eleventh day. Hiss, 4 in an investi- 

 gation of the same subject, obtained the 

 following results: 



First to tenth day, inclusive, twenty- 

 eight cases examined; typhoid bacilli isolated 

 from three; percentage of positive cases 

 10.7 per cent. 



Eleventh to twentieth day, inclusive, forty-four cases examined; ty- 

 phoid bacilli from twenty-two; percentage of positive cases 50 per cent. 



Twenty-first day to convalescence, sixteen cases examined; typhoid- 

 bacilli isolated from thirteen; percentage of positive cases 81.2 per 

 cent. 



The difficulties encountered in such examinations have led to the 

 development of a large number of methods. The first method which 

 yielded successful results was that of Eisner, 5 who employed a potato- 

 extract gelatin containing one per cent of potassium iodid, a medium 

 which prevented the growth of many intestinal bacteria, allowing only 



1 Wiltschour, Cent. f. Bakt., 1890. 



2 Redtenbacher, Zeit. f . klin. Med., xix, 1891. 



3 Horton-Smith, Lancet, May, 1899. 



4 Hiss, Med. News, May, 1901. 



6 Eisner, Zeit. f . Hyg., xxi, 1895. 



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FIG. 89. BACILLUS COLI. 

 Deep colonies on Hiss plate 

 medium. 



