RELAPSING FEVER 191 



the acme of the fever or at the crisis might be thought to 

 be suffering from malaria, while, but for the occurrence 

 of the crisis, the diagnosis in severe cases might well be 

 that of septicaemic plague, especially should death ensue. 

 It may be added that the pneumonic form of plague may 

 resemble that of relapsing fever, though it is usually 

 much more severe, and the very abundant blood-stained 

 sputum, seen in pneumonic plague, is characteristic when 

 it occurs. 



It is quite possible that cases of relapsing fever accom- 

 panied by severe jaundice and bloody vomiting, occurring 

 in countries in which yellow fever prevails, might easily be 

 mistaken for that disease. The discovery, of the Spirillum 

 obernieieri in the blood is therefore sometimes the only 

 means by which a positive diagnosis can be arrived at. 



It is essential, therefore, that in all cases in which the 

 diagnosis of relapsing fever is doubtful the blood should 

 be carefully examined for this parasite. Moreover, in 

 view of the differences which have been described in the 

 spirilla of relapsing fever cases occurring in different 

 parts of the world, and of the discovery of a similar 

 parasite in the blood of persons suffering from African 

 tick fever, the examination of the blood in cases in which 

 the clinical diagnosis has been well established is of great 

 interest and importance. It should be remembered that 

 the spirillum can usually be found in the blood only 

 during the febrile period, as it disappears at the crisis and 

 reappears only with the onset Of a relapse. This state- 

 ment is not absolute, however, for cases are not infrequent 

 in which spirilla have been discovered, though in greatly 

 diminished numbers, in the blood of patients during the 

 early part of the apyrexial period. For the discovery of 

 the spirilla, either fresh, unstained, or dry, stained films 

 may be used. In either case the search may be easy or 

 difficult, depending upon the number of parasites present, 

 this varying greatly. In some cases they may be so 

 numerous as to make the whole of the field of the 

 microscope seem in active motion, while in others careful 



