ENTOMOLOGY

LOUSE BORNE DISEASES 293one of these men on the second day of fever inoculated in another volunteerproduced a typical attack after an incubation period of five days. As thelice will usually leave a man with fever and migrate to a man with normaltemperature, it is easy to see how the disease is propagated.The British Trench Fever Committee's reports presented by MajorByam and others (1918) summarize the findings of the committee under18 paragraphs. They proved transmission of the fever by the feces oflice, that the disease is not native to the louse, and that it is not hereditarilytransmitted. The feces of the lice were only infective on the eighthto twelfth day after the lice had taken up the virus, proving a developmentalcycle in the lice. Transmission by the bite alone was not obtained.The incubation period after inoculation is at least (ight days.On the other hand the American Trench Fever Committee (Opie 1918 ;Strong, etc., 1918) claims that the fever is transmitted by the bite ofthe 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 theincubation period after inoculation. They claimed that the virus is notfilterable, but is inoculable. The patients were allowed to scratch, andprobably this was the way inoculation took place. It is quite possible,however, after lice have been confined on the skin for a time and haveconsequently covered the entir~ surface with their excreta, that they mayinoculate the virus when they puncture the skin through this film ofexcreta.Arkwright, Bacot, and Duncan (1918) published a long series ofstudies with Rickettsia bodies which they think show Ii very possibleconnection with trench fever. Apparently these bodies occurred principallyin lice capable of causing infection. The lice do not show thesebodies in their feces nor do their feces become infective until five to tenor twelve days after feeding on infective blood. The majority of licewhose 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 Rickettsiaquilntana, the bodies found associated with trench fever. Rickettsia isfound in the lice on the fifth to twelfth days after feeding on a trenchfever patient. Lice are infective on the fifth to twelfth days. Infectedlice contain Rickettsia and their feces are high in the bodies. There isno hereditary transmission in lice. Whether Rickettsia is the cause orthe product of the contagium, is undetermined.L. Convy, and R. Dujarric de la Riviere (1918) described Spirochaetagallica as a probable cause of trench fever.The Haemogregarina, gracilis Wenyon, suspected to be connected withthe disease, has since been proven not to have any connection.Bradford, Bashford, and Wilson claim to have found a filterable virus