478 VETERINARY BACTERIOLOGY 



Virus of Pleoropneomonia 



Disease Produced. Pleuropneumonia, peripneumonia, lung 

 plague of cattle and other bovines. 



Nocard and Roux described the causal organism in 1898. The 

 disease itself has been known in Europe for several centuries. 



Distribution. The disease is known from Europe, Africa, 

 Australia, Asia, and has been imported into the United States, 

 where, in 1886, it killed 10,000 animals in Illinois alone. 



Nature of Virus. The causal organism is doubtless a bacterium 

 that is just at the limit of visibility. In suitable fluids it may be 

 observed under very high powers as a tiny motile point. Bouillon 

 inoculated with the serous exudate from the pleura or from one 

 of the areas of consolidation in the lungs, sealed in a collodion 

 sac, and placed in the peritoneal cavity of a rabbit for two weeks, 

 will show a slight clouding or opalescence. Transfers to new media 

 similarly treated will likewise result in growth. This material 

 may be shown to be infective. The organism may also be cul- 

 tivated in a mixture of bouillon and blood-serum outside the animal 

 body. In two to three days it shows a very faint clouding. Agar 

 containing serum develops delicate, transparent, almost invisible, 

 colonies. The optimum temperature is 37; no growth occurs 

 under 30. 



Pathogenesis. Injection of pure cultures of the organism into 

 cattle results in infection. Intrapleural injections or inhala- 

 tions of the organism result in a typical clinical picture of the 

 disease. The disease is characterized by more or less extensive 

 areas of hepatization in the lungs and an inflammation of the 

 pleura, accompanied by a serofibrinous exudate. The amount of 

 fluid which collects may be very considerable. 



Immunity. Recovery from the disease results in a relatively 

 permanent immunity. Immunization against the disease by 

 vaccination with serum from the pleural cavity of infected animals 

 has been practised. The material is injected subcutaneously. 

 Its use is attended with danger, as from 0.5 to 5 per cent, or even 

 more of those vaccinated have been killed by the vaccine. The 

 method in question has been of some u c .e in immunization, but a 

 stamping-out process would appear to be more efficacious. 



Nocard and Roux have advised vaccination with pure cultures, 



