171 



PouLERTOX (Major A. (l R.). On Typhus Fever.— J?. R.A.M.C, 

 London, xxix, no. 2, August 1917, pp. 224-228. 



A noticeable feature of the typhus fever occurring in the Austro- 

 Oerman armies during the present war has been the frequent 

 association in the same patient of typhus fever with some other 

 infective disease, such as influenza, diphtheria, dysentery, malaria, 

 tvphoid and relapsing fevers ; this varied association of infection is 

 ■doubtless the result of cross-infection in military hospitals by the 

 agency of typhus-infected lice. Similar cross-infection has occurred 

 in at" least ' one instance in connexion with relapsing fever. The 

 spirochaete of relapsing fever is certainly carried by Uce, by ticks, and 

 possibly by other parasites, while it is equally certain that the louse 

 is a carrier of the typhus fever virus, probably the only common 

 carrier, so much so, that a typhus fever patient who has been freed 

 from lice is considered to be no longer a source of danger to others. 

 The seasonal prevalence of typhus among troops in the field is correlated 

 with a seasonal prevalence of lice, this fever being, in temperate 

 climates, essentially a winter disease, due to the wearing of additional 

 clothing, less thorough washing, and the sleeping in a more crowded 

 manner in billets. Similarly the association of typlms fever with times 

 of privation and famine is probably due to a v/idespread neglect of 

 personal cleanliness and consequent increased prevalence of lice. 

 Relapsing fever also appears to be most prevalent under colder 

 climatic conditions. 



The parasite causing typhus fever has not yet been positively 

 identified, but two suggested parasites must be considered, the Plotz- 

 Olitsky-Baehr bacillus and Rickettsia prowazeJd [see this Review, 

 Sev. B, V, p. 110]. It is not apparent that the former has any causative 

 relation to typhus infection, since its injection into the guinea-pig did 

 not produce the sequence of symptoms produced by the injection of 

 blood from a case of typhus fever, nor did it protect the guinea-pig 

 against a subsequent inoculation with actively virulent typhus-infected 

 blood. On the other hand it is highly probable that the organism, 

 R. prowazeki, which has been identified in the cells of the intestinal 

 •epithelium of lice taken from cases of typhus fever, represents a phase 

 in the development of the causative agent, which is probably a 

 protozoon. 



The comparison of the niethod of transmission of the spirochaete 

 •of relapsing fever with that of the unknown virus of typhus fever is 

 interesting. In relapsing fever the transmission is direct, the louse 

 being one of several accidental insect carriers. Its faeces contain the 

 spirochaete, which probably could be also transmitted by the bite, it 

 having been proved that the louse, after feeding on a patient with 

 relapsing fever, could at its next feed infect a healthy individual. 

 In the case of typhus fever on the other hand, the louse cannot transmit 

 the virus until seven days after the infected meal and does not transmit 

 it after the tenth day," the virus being contained in the body juices 

 of the louse and not occurring in the faeces. In other words the virus 

 of typhus fever after it has attained full activity in man must pass 

 through a phase of evolution in the louse before it can be transmitted 

 to a fresh human case, and the louse must be regarded as the necessary 

 intermediate host, just as some species of Anopheles are in the 



