RELAPSES 369 



another hypothesis. 1 The organisms in typhoid, Malta, and re- 

 lapsing fevers, are deposited in the spleen and internal organs, 

 multiply and form colonies there, which become protected from 

 the bactericidal substances by the formation of a non-anti-bacterial 

 envelope. When the anti-bacterial substances in the blood and 

 lymph have increased to such an extent as to penetrate and abolish 

 the non-anti-bacterial envelopes which surround these colonies, 

 the production of toxins will be so diminished that the temperature 

 will fall. If, however, for some reason or other, even a single 

 colony escapes the full anti-bacterial power of the lymph, owing, it 

 may be, to being shut off in a capillary which has become blocked, 

 or in some other part not freely infiltrated by the blood- or lymph- 

 streams, the bacteria of this colony will go on multiplying until the 

 blood has become modified in such a manner as to bring about a 

 diminution of the anti-bacterial substances, and thus render a 

 relapse possible. 



A third theory has been suggested by Durham. 2 He regards a 

 given infection as due to the " result of the action of a sum of a 

 number of infecting agents, each of which is similar but not identical 

 in its nature," the apparently simple infection being " in reality a 

 complex phenomenon brought about by a number of varieties and 

 sub-varieties of the given microbe." He suggests, therefore, that 

 in a typhoid infection a particular race of typhoid bacilli is in excess, 

 and when the anti-bodies for this particular race have been formed 

 in sufficient quantity, the disease process comes to an end. There 

 may, however, be present at the same time other races which have 

 produced little of their specific anti-bodies ; these then begin to 

 grow and multiply, and a relapse ensues. 



In the case of relapsing fever the organism may be a protozoon, 

 and in protozoal diseases relapses coincide with developmental cycles 

 of the parasite, e.g. in malaria. 



Clinical Diagnosis 



(1) Blood cultures. Three to 5 c.c. of blood are withdrawn 

 from a superficial vein with a syringe with aseptic precautions, 

 and 0-5 c.c. of the blood so obtained is sown into each of several 

 tubes containing 15 to 20 c.c. of sterile broth. The tubes are 

 incubated at 37 C., and if organisms develop these are isolated and 



1 Lancet, 1899, vol. ii, p. 1727 ; Sc. Mem. Med. Officers of Ind. Army, 

 pt. xii. 



2 Journ. Path, and Bact., vol. vii, 1901, No. 2, p. 240. 



2 4 



