HISTORICAL REVIEW 121 



essential points agreed with the conclusions and observations 

 of da Rocha-Lima. He was able to infect head lice with the 

 organism but insisted upon calling it a bacterium. 



Otto and Dietrich, in 1917, confirmed the presence of 

 Rickettsia prowazeki in lice fed upon typhus patients. In their 

 experiments of feeding 3000 lice upon 62 patients, 55 per cent 

 of their lice died. Of the 45 per cent which survived the ex- 

 periments, 20 per cent were infected with rickettsia. In 25 

 per cent rickettsia could not be demonstrated. In several 

 experiments, where the lice were permitted to feed sufficiently 

 long, 75 to 80 per cent became infected. The period of the 

 disease when lice are most easily infected is between the fifth 

 and the seventh days. After the thirteenth day the patients 

 no longer infect lice. 



Otto and Dietrich (1917, p. 579, fig. 2) described thread- 

 like forms of rickettsia from recently infected lice in addition 

 to the conventional rod and bi-polar forms and regarded these 

 thread forms as precursors of the small forms. 



Agglutination tests with suspensions of rickettsia obtained 

 from lice while not wholly satisfactory were interpreted by 

 Otto and Dietrich as confirmatory of the etiological relation- 

 ship of rickettsia to typhus. 



Other rickettsia in lice were found in 1916 by Topfer (1916 1>2>3 ) 

 in association with Wolhynian fever or trench fever, and by 

 Munk and da Rocha-Lima in 1917 in presumably normal lice. 

 Topfer (1916 1>2 ) reported the finding, in the blood of trench 

 fever patients, of diplo-bacillary and diplo-coccoid bodies, 

 and claimed to have produced a febrile reaction in guinea- 

 pigs by the inoculation of human trench fever blood and to 

 have observed the same bodies in the blood of the guinea- 

 pigs. In a third paper (1916 3 ), he reported the presence of the 

 organisms in lice fed upon Wolhynian fever patients. These 

 results were substantiated by Jungmann and Kuczynski 

 (1917 li2 ) who also found diplo-bacillary forms in the blood of 

 patients and in the feces and intestinal tract of lice fed upon 

 them. They were unable to differentiate between the micro- 



