CHAPTER X 
DISEASES CAUSED BY PROTOZOA 
GENUS PIROPLASMA 
General discussion of piroplasma. The genus Piroplasma belongs 
to the order Hemosporidia or blood dwelling sporozoa, cytozoic in 
mode of life in the blood constituents and with or without alternation 
of hosts. In.1888, Babes first described a blood parasite in European 
cattle which he designated Hematococcus bovis. In 1893, Starcovici 
gave it the generic name Babesia.* 
In 1893, Smith described the parasite that causes “Texas Fever’ 
in cattle which he named Pyrosoma bigeminum. The generic name, 
having been previously used for a genus of tunicates, was changed, in 
1895, by Patton to Piroplasma. Since that time a number of these 
parasites have been found in different animals. The organism causing 
East Coast fever in Africa was named by Theiler, in 1904, P. parvum. 
Babes described in 1892 a blood parasite in Roumanian sheep which is 
known as P. ovis. Piana and Galli-Valerio found in 1895 a similar 
parasite in dogs which is known as P. canis. In 1899, Gugliemi found 
a similar organism in the blood of horses which is known as P. equt. 
P. mutans is a widely distributed species found in the blood of cattle 
in South Africa. P. parvum is the cause of East Coast fever. Its 
generic name was changed to Theileria by Bettencourt. A number 
of other species have been described but they are of little etiological 
significance. 
Theiler describes a small body found in the marginal zone of the 
red blood corpuscle in certain cases of Texas Fever as Anaplasma 
marginalis. He differentiates this organism from P. bigeminum, 
P. mutans and P. parvum. 
The life history of these parasites is not known. In the infected 
animal they live within the blood, often entering into and destroying 
the red blood corpuscles. They are transmitted from the infected to 
*Most writers on protozoology accept the generic name Babesia on the assumption 
that the organism found by Smith and Kilborne is identical with the one described by 
Babes. On the other hand, most of the writers on the diseases caused by this parasite 
retain the name Piroplasma for the genus and Nocard’s term Piroplasmoses for the 
diseases produced by the different species. 
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