l86 TROPICAL MEDICINE AND HYGIENE 



of the first apyrexial interval also seven days, the first 

 relapse usually lasts five days and the second only two or 

 three days, while the interval between them is commonly 

 nine days. It will be evident that an attack of relapsing 

 fever with only one relapse lasts nearly three weeks. 



Considerable variations may occur in the temperature 

 of relapsing fever. Instead of by crisis, for example, the 

 fever may subside by lysis, and in some cases a secondary 

 rise may abruptly succeed the critical fall. 



The pulse during relapsing fever follows the course of 

 the temperature, though with a tendency, more marked 

 with each successive relapse, to lag behind. It rapidly 

 increases in frequency with the onset of the fever and 

 continues to rise, though more slowly, as the crisis is 

 approached. Its rate commonly reaches 120 per minute 

 during the first day of the disease rather more than that 

 in women and children and by the third or fourth day 

 of fever it may be 130 or even 140 per minute. With 

 the crisis the pulse-rate falls, though less rapidly than the 

 temperature. It may be unusually slow for a day or two 

 following the crisis, after which it returns to normal until 

 the relapse sets in. 



Although at first bounding, the pulse of relapsing fever 

 soon becomes soft and compressible, these features (which 

 are almost invariable) becoming more marked in propor- 

 tion to the duration of the disease. 



Corresponding with the condition of the pulse, the 

 heart almost invariably shows signs of weakness. The 

 impulse soon becomes weak and the first sound pro- 

 longed and booming. In rare instances, and these almost 

 always met with during the acme of the initial attack, 

 sudden heart failure occurs, causing fatal syncope. 



Respiration in an uncomplicated case of relapsing fever 

 corresponds with the pulse. There is commonly slight 

 bronchial congestion evidenced by cough and frothy 

 expectoration. With no further complications than this, 

 the breathing may be very rapid and the patient may 

 suffer from acute dyspnoea at the acme of the fever, 



