106 LICE AND THEIR MENACE TO MAN 



lice are capable of transmitting the disease at 

 two periods, firstly, just after they have imbibed 

 the infected blood, and secondly, after the elapse 

 of two or more days. They are most infective 

 on the sixth day after the infection, just before 

 the spirochaetes reappear in them, and from this 

 time the infectivity becomes less until it ceases 

 altogether. As in the case of the tick the off- 

 spring of the infected lice are capable of passing 

 on the disease. 



Isolated cases of relapsing fever are not of 

 themselves serious things. An average healthy 

 person would not as a rule die from it and it does 

 not usually leave serious after-effects. The drug 

 salvarsan nearly always aborts an attack in a few 

 hours and cures the disease, subsequent relapses 

 being rare. The danger of isolated cases occur- 

 ring in a country is that in times of misery and 

 distress, in war and in famine, vast epidemics are 

 liable to break out. They are the sparks amongst 

 the tinder, and wretched conditions of life are the 

 wind that blows the sparks into flame. Then, 

 when doctors and nursing staffs are overworked, 

 and the sick, ever increasing, in their already 

 enfeebled condition are unable to throw off the 

 complaint or to receive careful attention, the 

 mortality may be truly frightful. The great 

 epidemics are usually associated with those of 

 typhus, since the conditions favouring the spread 

 of both diseases are the same, as are also, very 

 largely, the areas where they occur. Chart IV. 



