306 SPIROCHAETOSIS IN FOWLS 
The duration of the disease in the acute form is usually from four to 
six days and in the chronic form from eight to fifteen or more days. 
The period of incubation in chickens is from seven to nine days after 
placing infected ticks upon them. 
Morbid anatomy. Wasted muscles and extreme anemia are the 
most pronounced lesions. In the acute cases the liver and spleen are 
enlarged. The liver contains numerous small areas of necrosis. The 
intestines are congested and at times show punctiform hemorrhages. 
There may be fatty degeneration of the heart and liver but this lesion 
is not considered specific for this disease. The spirocheta disappear 
from the blood soon after death and consequently are not usually 
detected in examinations made after death. In the chronic cases 
anemia and emaciation are very pronounced and the spleen may be 
atrophied. In fowls killed before the crisis, especially in the Brazilian 
form, the spirochetes are found widely distributed in the body. 
Prevention. As the spirochetes are transmitted from one fowl to 
another through the agency of the fowl tick the most effective way of 
prevention is to keep the premises thoroughly cleaned and the fowls 
freed from vermin. This can be done by dipping in a bath of sul- 
phurated lime solution. A 3% creolin solution has also been recom- 
mended. 
Immunity. The blood drawn from infected fowls is said not to be 
chickens it produces an immunity. Marchoux and Salimbeni found 
that the fresh blood from infected fowls heated for five minutes at 
55° C. has an immunizing effect but if heated for 10 minutes it loses 
that property. Salvarsan or ‘606’ has been found to be a strong 
spirochetacide. Balfour found that if this was given in sufficient 
doses it eliminated the spirochetes from the peripheral blood and in 
certain cases cured the fowl. It has little or no effect upon the granu- 
lar phase of the parasite. Abrin will destroy S. gallinarum. Atoxyl 
in 5 centimeter doses was found by Uhlenhuth, Gross and Bickel 
capable of preventing infection when given one or two days after 
exposure and also to be of therapeutic value but the blood of fowls 
thus treated remains infective. 
