50 
Lice and Disease 
of a patient in New York, the animals recovered, and were then found 
to be immune to “tabardillo” and vice versa. They regarded the New 
York strain of typhus as undoubtedly of European origin. Brill (vm. 
1911, pp. 196-218) who had made a clinical study of 255 cases, re¬ 
described the symptoms, described the pathology of a fatal case, and 
agreed that the disease he observed was similar to typhus. 
Prowazek (3. xi. 1913, pp. 2037-2040) inoculated Macacus rhesus 
intravenously (1) with 1-5 c.c. of human blood drawn on the sixth day 
of the disease, and (2) with twice washed citrated blood drawn on the 
19th day of the disease. Both experiments were positive. He reported 
the successful infection of guinea-pigs with the virus after its passage 
through monkeys. 
4. The virus of Typhus maintained by Passage through Different 
Animals. 
Nicolle (14. iv. 1915, pp. 160-161) reported that he was able to 
maintain the virus of typhus in a state of undiminished virulence by 
passage through guinea-pigs, monkeys and lice 1 . In two experiments 
he transmitted the virus through a series of (a) 16 and ( h ) 22 guinea- 
pigs respectively, and found it still virulent for monkeys. The inocula¬ 
tion of small doses of virus from guinea-pigs did not cause infection, 
but appeared to render the inoculated animals immune. Nicolle and 
Blaizot (1. iv. 1916, pp. 127-134) subsequently reported upon further 
passage experiments: a virus, obtained in April 1914 from an Algerian 
case of typhus, was maintained for two years in the laboratory by means 
of 61 passages through monkey—guinea-pig—monkey—louse—monkey 
—louse—monkey—16 consecutive guinea-pigs—one monkey—35 con¬ 
secutive guinea-pigs. A second virus, obtained in May 1914 from a 
Maroccan case, was maintained by passage through one monkey— 
59 consecutive guinea-pigs. They found it best to transmit the virus 
by intraperitoneal inoculation of heart-blood in quantities of 2-3 c.c., 
several animals being inoculated at a time to avoid a possibly negative 
result. 
5. The Experimental Demonstration that Lice convey Typhus. 
The well-known similarity between the epidemiology of typhus 
and relapsing fever, coupled with the work upon the latter disease 
carried out by Mackie, Smith and especially Sergent and Foley in 
1 See the next section (5) regarding lice. 
