PATHOLOGY— MORBID ANATOMY 



1375 



The bacilli can occur in any part of the body, but they have a 

 predilection for the lymphatic system. When arrested in the lym- 

 phatics of the skin, they give rise to the rose-coloured maculo- 

 papules so characteristic of the disease. The appearance and dis- 

 tribution of these red maculo-papules in the skin of the anterior 

 abdominal wall, chest, and back is believed by Greenhalgh to agree 

 with the cutaneous distribution of the nerves which supply the 

 small intestine, the mesenteric lymph nodules, and the spleen. But 

 this seems hardly possible, as papules can appear on the arms, legs, 

 and other regions. It would appear as though local heat was a 

 more important factor in their production than nerve-supply. The 

 bacilli may attack the respiratory system, giving rise to bronchitis, 

 pneumonia, etc., and they are commonly found in the gall-bladder, 

 in which they cause cholecystitis, and may give rise to gall-stones. 

 They also pass through the kidney into the urinary passages, and 

 at times appear in large quantities in the urine (bacilluria). 



They are also capable of living locally in the tissues, giving rise to 

 inflammation, abscess formation, and local death of the tissue. 



It has already been noted that they can live for years in the 

 gall-bladder and the pelvis of the kidney, producing the chronic 

 intestinal and urinary carriers, who are liable to infect, not merely 

 themselves, but others also. 



Auto-infection may possibly be the explanation of such cases as 

 have second or even third attacks, within a short period after the 

 first attack. 



The typical gradual onset of the disease may be explained by the 

 struggle between the antitoxins of the body and the bacterial toxins. 



The occasional sudden onset seen especially in the tropics may be 

 due to lowered resistance, owing to many causes^ — e.g., climatic in- 

 fluences, other infections, etc. 



Immunity is generally acquired after an attack, but second 

 attacks are by no means rare; moreover, the immunity is homo- 

 logous — viz., an attack of typhoid fever will protect against B, 

 typhosus, but not against the paratyphoid bacilli. 



The fever is due to a lessened loss of heat rather than to an in- 

 creased production of heat, and this is the reason why, in ordinary 

 cases, there may not be marked emaciation. 



Morbid Anatomy. — On opening the abdomen in a typical post- 

 mortem, the bowels will usually be seen to be distended with gas, 

 and the small intestine will be noticed to present marked areas of 

 congestion, especially near the ileo-caecal junction. 



The mesenteric glands will be observed to be enlarged and con- 

 gested, as will the spleen and at times the liver. If there has 

 been a perforation, a faecal odour will be perceived on opening the 

 abdomen, and there may be gas, faecal matter, round worms, or pus 

 in the peritoneal cavity, while careful search will reveal the perfora- 

 tion; but care must be taken not to artificially perforate the gan- 

 grenous, or almost gangrenous, intestinal wall by manipulation. 



On opening the intestines, it will be noted that the most important 



