RELAPSING FEVER 43 



Although relapsing fever was known to physicians over a 

 century ago, it was not until 1873 that Obermeier discovered 

 the hitherto unseen agitator which causes it; he made his dis- 

 covery during one of the epidemics which spread from Russia 

 over Poland and Prussia. 



Many great epidemics have swept Russian, Austrian and 

 Balkan cities. Early in the present European war Serbia was 

 held in the grip of an epidemic of relapsing fever of unusual 

 severity and of high fatality. In Bombay and other Indian 

 cities the oriental type of the disease is nearly always present, 

 and it sporadically appears in various parts of North Africa, 

 China and Japan. In tropical Africa it occurs over a large 

 part of the continent occupied by the tick which transmits it. 

 It is also probably widely distributed throughout Mexico and 

 Central and South America. In the United States it occurs 

 chiefly as irregular epidemics among immigrants. Just recently 

 a small epidemic occurred in Colorado. 



Transmission. — In Africa, where the disease is commonly 

 known as " tick fever," it was thought for a long time to be the 

 result of the poisonous nature of the bite of a common house- 

 infesting tick, Ornithodorus mouhata (see p. 360, and Fig. 155). 

 This tick, which inhabits the huts of natives throughout Central 

 Africa, is the chief if not the only transmitter of the Central 

 African relapsing fever spirochsete, Spirochceta duttoni. It can 

 infect both man and monkeys by its bite. 



It has been shown that the spirochsetes can live for a long time 

 in the ticks though they apparently disappear from the digestive 

 tract after nine or ten days, many of them penetrating to the 

 blood-filled body cavity while still in the spirochaete form. Leish- 

 man found that the spirochsetes break up into a series of tiny 

 granules which penetrate many of the organs of the tick, in- 

 cluding the ovaries and eggs. When the ticks are exposed to a 

 temperature of 95° F. for a few days the spirochsetes reappear. 

 The ticks may remain infective a year and a half after feeding 

 on an infected person though frequently fed on clean blood in 

 the meantime, and a single tick may, therefore, infect a number 

 of people. By means of the granules the spirochsetes may be 

 passed on to a second, or even to a third, generation of ticks 

 through the eggs. Young ticks reared in the laboratory from 

 infected parents have been found capable of transmitting the 



