LOUSE BORNE DISEASES 293 



one of these men on the second day of fever inoculated in another volunteer 

 produced a typical attack after an incubation period of five days. As the 

 lice will usually leave a man with fever and migrate to a man with normal 

 temperature, it is easy to see how the disease is propagated. 



The British Trench Fever Committee's reports presented by Major 

 Byam and others (1918) summarize the findings of the committee under 

 18 paragraphs. They proved transmission of the fever by the feces of 

 .lice, that the disease is not native to the louse, and that it is not heredita- 

 rily transmitted. The feces of the lice were only infective on the eighth 

 to twelfth day after the lice had taken up the virus, proving a devel- 

 opmental cycle in the lice. Transmission by the bite alone was not ob- 

 tained. The incubation period after inoculation is at least eight days. 



On the other hand the American Trench Fever Committee (Opie 1918 ; 

 Strong, etc., 1918) claims that the fever is transmitted by the bite of 

 the lice from 19 to 25 days after the virus was taken up by the lice. 

 This is probably the sum of the developmental period in the louse and the 

 incubation period after inoculation. They claimed that the virus is not 

 filterable, but is inoculable. The patients were allowed to scratch, and 

 probably this was the way inoculation took place. It is quite possible, 

 however, after lice have been confined on the skin for a time and have 

 consequently covered the entire surface with their excreta, that they may 

 inoculate the virus when they puncture the skin through this film of 

 excreta. 



Arkwright, Bacot, and Duncan (1918) published a long series of 

 studies with Rickettsia bodies which they think show a very possible 

 connection with trench fever. Apparently these bodies occurred prin- 

 cipally in lice capable of causing infection. The lice do not show these 

 bodies in their feces nor do their feces become infective until five to ten 

 or twelve days after feeding on infective blood. The majority of lice 

 whose feces showed Rickettsia were infective and caused trench fever, 

 while the majority which did" not show Rickettsia were not infective. 

 These same authors (1919) continued their studies with Rickettsia 

 qumtana, the bodies found associated with trench fever. Rickettsia is 

 found in the lice on the fifth to twelfth days after feeding on a trench 

 fever patient. Lice are infective on the fifth to twelfth days. Infected 

 lice contain Rickettsia and their feces are high in the bodies. There is 

 no hereditary transmission in lice. Whether Rickettsia is the cause or 

 the product of the contagium is undetermined. 



L. Convy, and R. Dujarric de la Riviere (1918) described Spirochaeta 

 gallica as a probable cause of trench fever. 



The HaemogregariTia gracilis Wenyon, suspected to be connected with 

 the disease, has since been proven not to have any connection. 



Bradford, Bashford, and Wilson claim to have found a, filterable virus 



