328 TEXAS FEVER 
losses from this disease. Cattle from these states shipped east brought 
the disease with them. The cattle commissioners of New York and 
the Board of Health of New York City endeavored to check the 
importation of such animals. It was carefully investigated at that 
time but nothing beyond a very accurate description of the gross 
lesions was accomplished. Later, Salmon determined the boundary 
line between the non-infected and the permanently infected districts, 
or what is now known as the Texas fever line. In 1889, the United 
States Bureau of Animal Industry undertook a systematic investiga- 
tion as to the nature of this disease, which resulted in the discovery of 
its specific cause by Dr. Theobald Smith and the demonstration of the 
fact that the cause of the disease is transmitted from southern to 
northern cattle through the medium of the cattle tick. Prior to this 
(1888), v. Babes had found an intraglobular parasite in the bloced of 
cattle suffering from an epizodtic disease (hemoglobinuria) in 
Roumania. While at first these diseases were thought to be different 
in their etiology they are now believed to be identical. 
Geographical distribution. In the United States the distribution of 
Texas fever corresponds with that of the blue cattle tick (Margaropus 
(Boéphilus) annulatus). This includes, with possibly a few small 
exceptional areas, that portion of the country south of the “Texas 
fever line.” It has been identified with the tick fever of Australia 
which has become a source of great loss to the cattle industry of that 
country. Ligniéres has identified the disease in South America 
(Argentine Republic). It is also reported to be identical with a 
malady affecting cattle along the Danube river, in the Balkan provin- 
ces and in South Africa. It is restricted, however, to those countries 
where the climate is not sufficiently severe to destroy the cattle tick 
during the winter season. Cattle (genus Bos) are the only animals 
which suffer from it. 
Etiology. Texas fever is caused by a microérganism belonging in 
the protozoa discovered by Smith and named by him, Pyrosoma 
bigeminum.* The generic name Piroplasma given it by Patton is 
generally accepted. 
It seems that Dr. Stiles, in 1868, observed this organism but failed 
to recognize its significance. It is found in the blood in cases of Texas 
*The genus of the parasite has been changed to Piroplasma by Patton, to Apiosoma 
by Wandelleck, to Awembosporidies by Bonome, and Proteus virulentissimus by Perron- 
cito. Starcovici has named the organism described by Babes as Hematococcus, 
Babesia bigeminum bocvis. 
