RELAPSING FEVER 193 



Microscopically the hypertrophy of the spleen is found 

 to be due both to proliferation of its cellular elements 

 especially of the Malpighian corpuscles and to vascular 

 engorgement. Spirilla may be found in the spleen both free 

 and in polymorphonuclear cells, often in great profusion. 



The enlargement of the liver is often marked and the 

 weight may be as much as 5 Ib. Though sometimes 

 dark and congested, it is more commonly pale and 

 mottled. Its substance is soft and the lobules are in- 

 distinct. There is cloudy swelling of the cells. 



Besides the conditions mentioned, the heart is usually 

 found to be pale and soft, the muscular fibres showing 

 signs of cloudy swelling and sometimes fatty degenera- 

 tion. The kidneys and other abdominal organs are also 

 in the condition of cloudy swelling. The inflammation 

 of the intestinal tract is often considerable. The stomach 

 is the part most commonly affected and there are usually 

 numerous small haemorrhages beneath the mucous 

 membrane. In cases complicated by diarrhoea or 

 dysentery there is intense congestion of the ileum and 

 colon, which may even be superficially ulcerated. 



A certain amount of bronchial catarrh is usually found, 

 but in uncomplicated cases the lungs are pale. 



Two forms of pneumonic consolidation may be met 

 with. The more common form is that in which patches 

 of consolidation, often of considerable size, are scattered 

 through both lungs ; they may be met with in any part 

 of the lobes and are not more common at the bases than 

 elsewhere. The other form of consolidation is similar to 

 that of ordinary croupous pneumonia. 



While inflammation of the brain or its meninges is rare 

 in relapsing fever, passive congestion as shown by venous 

 engorgement and serous exudation is not uncommon. 



Etiology. Relapsing fever is remarkable in being the 

 first disease shown to be due to a micro-organism. 

 During an epidemic in Berlin, in 1868, Obermeier dis- 

 covered in the blood of patients suffering from relapsing 

 fever a spirillum, which since the publication of the 

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