THE DIAGNOSIS OF PROTOZOAN DISEASES 135 
XI 
THE DIAGNOSIS OF PROTOZOAN DISEASES 
There are two diseases caused by trypanosomes and one 
by piroplasma that are liable to be encountered in this country ; 
namely, dourine, surra, and Texas fever. Surra has never 
been found in this country, but it has been brought to our quar- 
antine station, and it is possible that some carrier of the para- 
site may introduce it. Dourine, -however, has occurred in 
several places in the United States and Canada, and therefore 
may be met at any time. Texas fever prevails in certain sec- 
tions of the South. It is occasionally brought into the Northern 
states. , 
Surra. In cases of this disease the trypanosome may be 
found by a microscopic examination of the blood, either in the 
fresh condition or in stained cover-glass preparations when 
taken at the proper time during the active course of the disease. 
They are present in the peripheral blood for a short time only 
and then disappear. In case of suspected surra one can in- 
oculate subcutaneously mice, rabbits, or dogs with a few cubic 
centimeters of the blood and find the parasites in their blood 
after the symptoms appear or at death. The parasites are 
reported to be.scarce in the rabbit’s blood but numerous in 
that of mice. 
Dourine. The trypanosome of dourine is not usually found 
in the blood of the infected horse. It is, however, present in 
the cedematous swellings caused by it and in the serum in the 
early stages of the plaques which occur in many cases. The 
diagnosis of dourine by the presence of the parasite can be deter- 
mined, as a rule, only from a study of them in the local lesions. 
Texas fever. In fatal cases of Texas fever, one can make 
smear preparations from the liver, kidney, or heart muscle. The 
Firoplasma bigeminum are more numerous in the capillaries. 
