460 VETERINARY BACTERIOLOGY 



Theiler later elaborated an account of the disease and the organism 

 as it occurs in South Africa. 



Distribution. The disease has been noted from South Africa, 

 Central Africa, Algeria, Italy, Sweden, Russia, India, and Vene- 

 zuela. It is evident that further observation may show an ex- 

 tensive distribution 



Morphology. The organism is smaller than P. bigeminum, but 

 resembles it. It occurs singly or in pairs, or rarely in rosettes, in 

 the red blood-cells. Occasionally it is free in the plasm. The disease 

 was at first supposed to be non-transmissible by blood injection, 

 but Theiler succeeded by intravenous injections of virulent blood. 



Pathogenesis. The disease is characterized by jaundice and a 

 high fever. It may run an acute or a chronic course; frequently 

 it is fatal within a few days. The lymph-nodes and the spleen 

 are considerably enlarged. Animals born in infected districts 

 are commonly immune. 



Transmission. The disease is believed to be transmitted by 

 ticks. 



Piroplasma ovis 



Disease Produced. Hemoglobinuria, malarial catarrhal fever, 

 or icterohematuria in sheep. 



Babes, in 1892, first noted the parasites in the blood-cells of 

 sheep in Rumania at the time that he made his observations on 

 piroplasmosis of cattle. 



Distribution. It has been noted from Italy, France, Turkey, 

 Venezuela, and the West Indies, South Africa, Rumania, and 

 probably in the United States (Montana). 



Morphology. It is similar to P. bigeminum, but smaller (1 to 

 1.8 ^ in diameter). It is commonly single, sometimes double, in the 

 cells, and frequently occurs in the plasm. 



Pathogenesis. The disease may be transferred by the injec- 

 tion of blood containing the organisms into healthy animals. The 

 incubation period is about eight to ten days. Other animals, 

 including cattle, cannot be infected. The disease is commonly 

 fatal. It is characterized by anemia, icterus, and frequently 

 hemoglobi nuria. 



Transmission. The disease is transmitted through the bite of 

 a tick (Rhipicephalus bursa). 



