SPIROCHETOSIS AND RARE INFECTIOUS DISEASES 141 
gram was the maximum dose tolerated. The curative dose on the 
second day of infection when spirochetes were observed in the blood, 
varied from .02 to .003 gram per kilo of body weight. Even the 
lowest dose caused the disappearance of spirochetes from the circu- 
lation and the birds recovered. Birds treated on the third day of 
infection received doses varying from .03 gram to .0025 gram per 
kilo of body weight. The lowest dose that uniformly caused the dis- 
appearance of the spirochetes was .005 gram per kilo. A dose of 
.05 gram per kilo was effective when administered to birds on the 
fifth day of infection. Aragao recommends atoxyl in a dose of .03 
gram, salvarsan .0035 gram and neosalvarsan in .0015 gram per 
kilo of body weight. 
Immunization. An attack of spirochetosis confers a certain 
amount of immunity. The blood serum of such a bird possesses 
strong immunizing properties and shows marked agglutinative action 
in vitro. 
Aragao induces immunity by injecting a vaccine prepared from 
the blood of infected fowls. On the fifth day of the infection the 
blood is drawn aseptically into flasks holding 300 e.c. each and de- 
fibrinated by shaking with shot. Blood drawings from the various 
fowls are mixed to secure a uniform distribution. The defibrinated 
blood is distributed in quantities of 50 c.c. each in flasks of a ca- 
pacity of 125 ec. The flasks are plugged with cotton which has 
been dipped in formalin. The fluid is left thus exposed to the 
vapor of formalin for eight days and is shaken occasionally during 
that period. After carrying out suitable tests for sterility, it is in- 
jected subcutaneously in one c.c. doses for immunizing birds be- 
fore introduction into infected flocks. A similar product is pre- 
pared by Aragao by mixing defibrinated blood and glycerine in equal 
parts, omitting the formalin vapor treatment. It is used in two cc. 
doses and is preferred to the one prepared by using formalin. A 
single injection is employed, for subsequent attacks by ticks in an 
infected flock are relied upon to strengthen the immunity. In unin- 
fected flocks where the vaccination is employed as a protection 
against imported infection only, revaccination is recommended once 
a year. 
Marchoux and Salimbini have observed that the virulence of the 
spirillum in blood is greatly diminished or lost after a period of about 
48 hours. They produce successful vaccination by using virulent 
blood held for two to four days, or after heating at 55°:C. for five 
to ten minutes. 
