DISEASES OF UNKNOWN ETIOLOGY 427 



is a disease of tlie horse caused by a filterable virus found 

 in the blood, in the urine and the feces of infected animals. 

 Blood sera from animals showing symptoms of the dis- 

 ease inoculated into susceptible individuals produce the 

 disease after 5 to 9 days or more. The first symptom is 

 fever. The disease may be characterized as an acute or 

 chronic anemia. There is a great destruction of blood cells. 

 Together with this there is degeneration of kidneys and 

 liver and changes in the blood vessels. The spleen becomes 

 enlarged and frequently degenerates and the bone marrow 

 shows profound degeneration. The disease generally proves 

 fatal. Methods of transmission of the disease have not been 

 satisfactorily worked out. 



Typhus Fever 



This is an acute infectious disease of man. It has been 

 recorded in the United States under the name, Brill's dis- 

 ease in mild form in the city of New York, and as tabardillo 

 in Mexico. The disease is transmitted from man to man 

 by means of the body louse, occasionally by the head louse. 

 The disease may also be transmitted to the monkey. 



