I320 



THE RELAPSING FEVERS 



to the wound produced by the tick's bite, by being voided in the 

 Malpighian secretion passed by the tick during feeding, or perhaps 

 by regurgitation of the intestinal contents. More recently Leish- 

 man and Hindle have shown that the tick produces infection only 

 as the result of its infected faeces contaminating the tick-bite. This 

 is a typical example of the contaminative mode of infection. 



The principal predisposing causes are anything which facilitates - 

 the life of the tick, such as bad hygienic conditions, which are well 

 exemplified by the native huts of Africa. These huts contain many 

 cracks in the walls and floor, which afford shelter to the tick, and 

 hence predispose to the disease. 



Pathology. — ^Very little can at present be said as to the pathology. 

 The post-mortem reveals only an enlarged firm spleen, while smears 

 taken from the liver and lungs show large numbers of spirochsetes. 



Symptomatology. — ^The symptomatology still requires careful 

 investigation on the lines carried out by Carter in India, but much 

 good work has been done on the subject by Button, Todd, Ross, 

 and others. 



Incubation.- — -The period of incubation is usually about seven 

 days, but it may extend to eleven or twelve days. 



The tick-bite may be accompanied by local inflammatory s^^mp- 

 toms, but in some cases the bite is not even noticed. According to 

 Wellman, natives believe that when the tick-bite is accompanied by 

 a severe local reaction, the individual probably escapes fever, and 

 Nuttall calls attention to the possible protective effect of a local 

 reaction. 



Usually mental heaviness, lack of activity, profuse sweating, and 

 constipation, are mentioned as prodromal symptoms. 



Onset.- — -The attack may come on gradually, with a feeling of 

 malaise, faintness, and a disinclination for food, or even vomiting, 

 and a slight rise of temperature. In a few hours the temperature will 

 have risen to 103° to 105° F., associated with headache, pains in 

 the back and limbs, and intense pain in the region of the spleen, and 

 chilliness. There is vomiting, first of food, and then of bile, with 

 often diarrhoea, and even at times streaks of blood in the motions. 

 The spleen is generally found to be enlarged, and spirochaetes in 

 scanty numbers occur in the peripheral blood, but may be hard to 

 find. 



Course. — The next day the symptoms are worse, and the patient is 

 hot and restless, complaining of thirst and splenic pain, and often 

 troubled by a cough. The temperature shows a morning fall, without 

 improvement in the symptoms, and an evening rise, during which 

 the pains increase, and the patient may become delirious. The 

 liver does not enlarge, but the spleen projects below the costal - 

 margin. Spirochsetes are now found in greater numbers, but 

 diminish remarkably before the crisis. There is a slight decrease 

 in the red cells and haemoglobin, and a marked leucocytosis before 

 the crisis, while polychromatophile degeneration is noted in the 

 red cells, and a very marked increase in blood platelets. The 



