486 VETERINARY BACTERIOLOGY 



In a small percentage of the cases nervous symptoms develop. 

 The discharge from the mucous membranes is highly infective. 

 Secondary infection with bacteria is common, and is believed by 

 some investigators to account for many of the deaths. 



Immunity. Many attempts have been made to prepare an anti- 

 or immune serum that would be efficacious in preventing or curing 

 the disease. Several have been placed upon the market, but none 

 has been shown to be efficacious. It is possible that success 

 might be attained by the use of hyperimmune blood. 



Transmission. The disease is transmitted by direct or indirect 

 contact with infected individuals. 



Virus of Fowl Plague 



Disease 'Produced. Fowl plague, chickenpest of domestic 

 fowls. 



This disease has generally been confused with chicken cholera, 

 which it closely resembles clinically, although Penoncito un- 

 doubtedly described it in 1878. Centanni and Savonuzzi, in 1901, 

 showed that the virus could pass through a porcelain filter. This 

 has been amply confirmed by other writers. 



Distribution. The disease is known only from northern Italy, 

 the Tyrol, Germany, and France. 



Character of the Virus. The organism is a filterable virus, and 

 is probably ultramicroscopic, although Rosenthal, Kleine, and 

 Schiffman have described bodies in the nerve-centers that are 

 possibly protozoan in nature. The virus is found in the blood, the 

 nasal secretion, and generally throughout the tissues. The blood 

 retains its virulence for three months when sealed in tubes and 

 kept in a dark place. The thermal death-point is 55 for thirty 

 minutes or 60 for five minutes. The dried virus has been found 

 to retain its virulence for two hundred days, and in glycerin and 

 serum mixture for two hundred and seventy days. It is easily 

 destroyed by disinfectants. 



Pathogenesis. Injection of as small amount as [^55 c - c - of 

 virulent blood or secretions is sufficient to infect. The virus 

 is pathogenic for many birds besides fowls, but not for mam- 

 mals. The disease is characterized by the hemorrhages into 

 the serous membranes in acute cases, and in the less acute edema 



