TICK FEV 7 ER 203 



submitting them to the bite of the ticks which had been 

 caught in native houses, or which had been reared from 

 the eggs of such ticks. These ticks were also identified 

 as 0. moubata. Button and Todd also gave the disease 

 to monkeys, guinea-pigs and rats by injection of infected 

 blood. 



They were not able to find spirochaetes in the ticks 

 which transmitted the fever to monkeys, but Koch shortly 

 afterwards, in German East Africa, demonstrated that 

 not only the infected ticks were infective, but also that 

 their eggs must be infected, as the second and third 

 generations \vere capable of infecting susceptible animals. 



Koch also successfully infected mice and rats by the 

 bites of infective ticks and their offspring. 



Breinl and Kinghorn, working at Liverpool with 

 ticks infected in the Congo Free State, have been 

 able to infect a number of laboratory animals with the 

 spirochaete. While they were unable to separate this 

 spirochaete from the S. obermeieri by any morphological 

 differences, they showed that each spirochaete conferred 

 immunity against itself but not against the others. 



They therefore considered the spirochaetes to be 

 distinct species and named that causing tick fever 

 S. duttoni. Attempts to transmit these infections by bed 

 bugs failed. The symptoms produced in animals by 

 inoculation of these two different species of spirochaetes 

 are very similar, but there are slight differences. Inocu- 

 lation of S. duttoni produced a much more serious illness 

 than that caused by S. obermeieri, often causing death, 

 while no animals died of infection with the latter 

 parasite. In monkeys inoculated with S. duttoni, the 

 incubation period was usually shorter, the pyrexial attacks 

 longer and the relapses more frequent than in those 

 inoculated with S. obermeieri. 



The symptoms of tick fever in man resemble very 

 closely those of relapsing fever, so much so that Button 

 and Todd, from their experience of it in the Congo Free 

 State, expressed the opinion that the two diseases were 



