496 



RELAPSING FEVER 



in obtaining cultures in collodion sacs containing rats' blood 

 which were placed in the peritoneum of rats. By this method 

 cultures were maintained for many generations ; the organisms 

 were still virulent though the resulting infection was rather less 

 intense than at first. The spirochsetes are readily killed at a 

 temperature of 60 C., but may be exposed to C. without 

 being killed. Novy and Knapp have found that there is a single 

 flagellum at one end of this organism. 



Relations to the Disease. -In relapsing fever, after a period 

 of incubation there occurs a rapid rise of temperature which 

 lasts for about five to seven days. At the end of this time a 



crisis occurs, the tempera- 

 ture falling quickly to 

 normal. In the course 

 of about other seven 

 days a sharp rise of 

 temperature again takes 

 place, but on this occa- 

 sion the fever lasts a 

 shorter time, again sud- 

 denly disappearing. A 

 second or even third 

 relapse may occur after 

 a similar interval. The 

 organisms begin to appear 

 in the blood shortly 

 before the onset of the 

 pyrexia, and during the 

 rise of temperature rapid- 

 ly increase in number. 

 They are very numerous 



during the fever, a large number being often present in 

 every field of the microscope when the blood is examined at 

 this stage. They begin to disappear shortly before the crisis : 

 after the crisis they are entirely absent from the circulating 

 blood. A similar relation between the presence of the organ- 

 isms in the blood and the fever is found in the case of the 

 relapses. Munch in 1876 produced the disease in the human 

 subject by injecting blood containing the spirochsetes, and this 

 experiment has been several times repeated with the same result. 

 Additional proof that the organism is the cause of the disease 

 has been afforded by experiments on animals. Carter in 1879 

 was the first to show that the disease could be readily produced in 

 monkeys, and his experiments were confirmed by Koch. In such 



FIG. 148. Spiroohretes of relapsing fever in 

 human blood. Film preparation. (After 

 Koch.) See also Plate IV., Fig. 18. 

 x about 1000. 



