62 
Lice and Disease 
substance of crushed lice, when dropped upon the excoriated skin or 
upon the intact conjunctiva, produced relapsing fever in man. These 
cases were promptly cured in a few hours with salvarsan (or ludyl). 
In a later paper (26. vm. 1912, pp. 481-484), the authors state 
that a man was bitten 336 times by certainly infected lice and remained 
well, and that two persons did not become infected after being bitten 
respectively 1186 and 2828 times by lice which were the progeny of 
infected parents. The authors reported three, experiments to determine 
if the injectivity of lice is hereditarily transmitted ; two experiments were 
negative and one positive. The latter experiment was reported upon 
in their earlier paper 1 . Some eggs, laid 12-20 days after the parent 
lice had fed on relapsing fever blood, were placed at 28° C. and began 
to hatch on the seventh day. The young larval lice and some unhatched 
eggs were now crushed and inoculated into a monkey which subse¬ 
quently developed relapsing fever. Spirochaetes were not discoverable 
microscopically in the eggs. 
Of 165 lice examined from the ninth day onwards, after they had 
fed on infective blood, 29 (ca. 18 %) subsequently showed spirochaetes 
in their coelomic cavity. Of 39 SS arid 21 lice examined, respect¬ 
ively 10 % and 43 % subsequently showed coelomic infection, whilst 
spirochaetes were absent from the intestinal lumen and inoculations 
made with such lice gave negative results. 
Nicolle, Blaizot and Conseil published three papers on their investi¬ 
gations in the following year. In the first paper (12. ii. 1913, pp. 106- 
107), they report that in seven lots of body-lice fed on men or monkeys 
suffering from relapsing fever, rapid degeneration and disappearance 
of the spirochaetes was observed in a few hours, followed by their re¬ 
appearance after seven days. After about five days, the spirochaetes 
appeared in the coelomic cavity of the insects, and persisted there for 
8-12 days. The spirochaetes contained in the lice at this period were 
virulent for man and monkeys. They subsequently disappeared 2 . 
The authors’ second and third papers (in. 1913, pp. 204-205; and 
1 This experiment is also cited in their paper of m. 1913, p. 222. They express the 
belief (p. 223) that the spirochaetes persist in nature through their being hereditarily 
transmitted in lice. This we know is what occurs with the Spirochaete duttoni in the 
tick, Ornitliodorus moubata, in connection with the relapsing fever of tropical Africa. 
2 The authors failed to obtain similar results with Spirochaeta duttoni, which, as has 
already been stated, is transmitted by a tick occurring in tropical Africa. In lice fed upon 
a severely infected monkey, the spirochaetes disappeared within the insects after two 
hours and they failed to reappear in 59 lice examined. The authors therefore conclude 
that lice are not suitable hosts for S. duttoni. 
