FOWL PLAGUE 499 
and France. It has been thought that it came from Soudan and 
Egypt. 
Etiology. This disease is due to an invisible virus. The blood or 
aqueous suspension of crushed lungs or liver will usually produce 
the disease when injected in very small doses. It was found by 
Maggiora that 4 cc. of a dilution of virulent blood in which the blood 
was present in the proportion of 1 to 125,000,000 destroyed a young 
hen. 
The virus is present in the blood, nervous system, nasal secretions, 
intestine and exudates in the larger cavities. Landsteiner found 
serum slightly virulent when the blood was very virulent. The virus 
retained its virulence in blood kept in sealed glass tubes and in a dark 
place for three months. The filtrate was virulent for a week only. 
It was destroyed in thirty minutes at a temperature of 60° C. 
The period of incubation is usually from 3 to 5 days. After inocula- 
tion death occurs within 36 to 48 hours. 
Symptoms. According to Centanni, the chicken acts dumpish the 
first day and refuses food on the second. The feathers are ruffled, 
the comb discolored and on the third day it dies. More rapidly fatal 
cases are mentioned by Lode and Gruber. The temperature is at 
first high (110° to 112° F.) but it falls to subnormal before death. 
Morbid anatomy. The lesions vary. In some cases death follows 
so rapidly that autopsies reveal no appreciable tissue changes. There 
may be a slight pericarditis and ecchymoses in the heart muscle. 
There is an exudative pleuritis and peritonitis in some cases. Puncti- 
form hemorrhages are reported on the inner surface of the breast bone, 
serous membranes, in the fat about the gizzard and mucose of the 
respiratory passages. In Italy it is reported that a fibrinous exudate 
often occurs on the pleure and peritoneum. The lungs are congested 
and occasionally there are collapsed areas. The liver, spleen and 
kidneys are more or less changed. 
Diagnosis. The diagnosis is to be made by the symptoms and 
lesions. According to Freese, “One is entitled to assume a bird has 
died of avian plague if one finds hemorrhages in the glandular stomach 
(proventriculus), swelling of the kidneys, marked injection of the blood- 
vessels in the serosa of the Graafian vesicles, not infrequently accom- 
panied by hemorrhages, and providing the disease assumes a plague- 
like form.” It is to be differentiated from fowl cholera which it 
