414 PATHOGENIC MICROORGANISMS 



system of sanitation. The disease is acquired by ingestion of the spe- 

 cific bacteria. Infection by other channels has not been demonstrated. 



Prophylactic measures in typhoid fever, therefore, should begin 

 with the isolation of the patient and the disinfection of excreta, dis- 

 charges, linen, and all utensils which have been in contact with the 

 patient. The bacilli leave the body in the feces and the urine and the 

 dangers of contamination, by these substances, of all objects in imme- 

 diate contact with the patient are considerable. Excreta should there- 

 fore be either mixed with boiling water or chemically disinfected, pref- 

 erably by means of thoroughly mixing with carbolic acid, lysol, or a solu- 

 tion of freshly slaked lime, and, if possible, destroyed by burning. 

 Linen, tableware, and eating utensils should be soaked in similar solu- 

 tions and boiled. The observance of such measures, furthermore, 

 should not be discontinued until bacteriological examination has demon- 

 strated the absence of the bacilli from feces and urine. Disregard of 

 this last precaution may well be one of the main causes of the endemic 

 persistence of the disease in large cities especially considered in the 

 light of our recent knowledge of " typhoid carriers." 



Typhoid fever, in the large majority of cases, is transmitted by 

 the agency of water. In an analysis of six hundred and fifty typhoid 

 epidemics Schuder 1 found four hundred and sixty-two reported, upon 

 reasonable evidence, as originating from water. The technical difficul- 

 ties attending the isolation of typhoid bacilli from contaminated water 

 have prevented actual bacteriological proof in most epidemics; never- 

 theless, indirect evidence of pollution of the suspected water-supply, 

 correspondence of the distribution of this supply with that of the dis- 

 ease, and reduction of typhoid morbidity upon the substitution of an 

 uncontaminated supply are sufficiently convincing to remove reasonable 

 doubt. Added to this is our knowledge, from the experiments of Jor- 

 dan, Russell, and Zeit 2 and others, that typhoid bacilli may remain 

 alive in natural waters for as long as five days. Prudden has demon- 

 strated that the bacilli may survive freezing as long as three months. 



Next to water, the most important source of typhoid fever is con- 

 taminated milk. In the summary by Schiider, 3 one hundred and ten 

 of the four hundred and sixty epidemics were attributable to milk. 

 No visible modifications in milk occur, which makes this source es- 

 pecially insidious. Contamination of milk has been traceable to water 

 used in washing cans or to dairy attendants. 



1 Schuder, Zeit. f. Hyg., xxxviii, 1901. 



2 Jordan, Russell, and Zeit, Jour, of Inf. Dis., 1, 1904. 3 Schuder, loc. cit. 



