Pathogenesis 595 



Reed, Vaughan, and Shakespeare* to be largely the result of the 

 pollution of the food of the soldiers by flies that shortly before had 

 visited infected latrines. 



The bacillus is also occasionally present upon green vegetables 

 grown in soil fertilized with infected human excrement or sprinkled 

 with polluted water, and epidemics are reported in which the occur- 

 rence of the disease was traced to oysters infected through sewage. 

 Newsholmef found that in 56 cases of typhoid fever about one-third 

 were attributable to eating raw shell-fish from sewage-polluted beds. 



Pathogenesis. — The primary activities of the typhoid bacillus 

 are unknown. It is supposed that it passes uninjured through the 

 acid secretions of the stomach to enter the intestine, where local dis- 

 turbances are set up. Whether during an early residence in the 

 intestine its metabolism is accompanied by the formation of a toxic 

 product, irritating to the mucosa, and affording the bacilli means of 

 entrance to the lymph-vessels, through diminutive breaches of con- 

 tinuity, is not known. We usually find it well established in the 

 intestinal and mesenteric lymphatics at the time we are able to 

 recognize the disease. 



It is quite, certain that the chief operations of the t3^hoid 

 bacillus are in the tissues and not in the intestine, as seems to be a 

 widely prevalent error. It is contrary to most of our knowledge of 

 the organism that it should easily adapt itself to saprophytic exist- 

 ence among the more vigorous intestinal organisms. Those who 

 look for it in the feces are usually surprised at the difl&culty of finding 

 it, or at the small numbers present. It is far more easy to isolate 

 the organism from the blood than from the feces, and much greater 

 numbers occur in the urine than in the feces. It probably es- 

 capes from the blood into the bile, where it grows luxuriantly, 

 and entering the gall-bladder may take up permanent residence 

 there, escaping into the intestine each time the gall-bladder is 

 emptied. Many bacilli thus discharged probably meet with destruc- 

 tion in the intestine, though some convalescents from typhoid fever 

 for years have a periodic appearance of bacilli in the feces. Such 

 individuals have become known as " typhoid carriers " and are a men- 

 ace to the public. 



In a case studied by MillerJ bacUli were found in the gall-bladder 

 seven years after recovery from typhoid fever; in a case studied by 

 Droba§ they were found in both the gall-bladder and a gall-stone 

 seventeen years after recovery from the disease; Humer,|| found 

 them in the gall-bladder of a patient suffering from cholecystitis, 

 eighteen years after recovery from an attack of typhoid fever, and in a 



* "Report on Typhoid Fever in the U. S. Military Camps in the Spanish War," 

 vol. I. 

 t "Brit. Med. Jour.," Jan., 1895. 

 t "Bull, of the Johns Hopkins Hospital," May, 1898. 

 § "Wiener klin. Wochenschrift," 1899, xii, p. 1141. 

 II "Bull, of the Johns Hopkins Hospital," Aug. and Sept., 1899. 



