446 INFECTIOUS DISEASES DUE TO PROTOZOA „ 



a few piroplasms of atypical form. If cattle so treated are, 

 two months later turned into infested pastures a large pro- 

 portion of them will resist natural infection. Some of them, 

 however, will show symptoms of fever which is usually 

 followed by recovery. The losses from this method of 

 immunization are about 10 per cent. Some animals of low 

 resistance die dining the process of immunization. This 

 method seems more controllable than the former one and is 

 now much employed to prevent losses among imported 

 susceptible cattle. 



Quarantine Line. — The United States Government has 

 established a quarantine line which extends from the seacoast 

 east of Norfolk, Virginia, across the country to the coast of 

 California near San Francisco. This line is a very irregular 

 one and is varied from time to time as counties just south of 

 it are freed from ticks. Roughly, at present, the, line extends 

 through the centre of Virginia, westward along the north 

 boundary of North Carolina, through the State of Tennessee, 

 along the north boundary of Arkansas to the centre of the 

 north boundary of Oklahoma, where it drops suddenly 

 taking a southwesterly course until it reaches the Mexican 

 line, along the north border of which it proceeds westward 

 until it reaches the east boundary of California which it 

 follows north as far as the latitude of San Francisco where 

 it again turns westward to the coast. 



Piroplasmosis of European Cattle {Infectious Hemoglobin- 

 uria of the Ox. ' 'Red Water" 1 ) . — Definition. — Piroplasmosis of 

 European cattle is an infectious blood disease very similar 

 to if not identical with American Texas fever. The disorder 

 is transmitted by a variety of the cattle tick. 



Occurrence. — This piroplasmosis is generally distributed 

 throughout Europe (Germany, Russia, Finland, Rumania, 

 etc.), where it assumes usually an enzootic form, outbreaks 

 occurring most commonly among cattle on pasture in the 

 spring and summer months. From tick-infested forage, 



1 The "red water" of British Columbia and of the' Northwestern United 

 States, according to Hadwin, is not due to protozoa, but to poisoning with 

 oxalic acid from the wet, undrained and infertile pastures. The disorder, 

 which is very fatal, usually occurs only among adult cattle. 



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