THE PARASITE OF TEXAS FEVER 787 



parva]), and this observation would tend to confirm Schaudinn's hypothesis ; 

 but Martini and Crawley have shown that the flagellated parasites seen by 

 Miyajima are not Piroplasmata and that he was dealing with a double 

 infection with two distinct parasites. 



1. Piroplasma bigeminum. 



Synonyms. Pyrosoma bigeminum. Babesia bigemina. 



Piroplasma bigeminum was the name given by Smith and Kilbourne to 

 the parasite causing Texas fever in cattle. Babes had previously recorded 

 the presence of the same hsematozoon in the haemoglobinuria of cattle associ- 

 ated with bacteria. The parasite has also been found in cattle suffering 

 from hsemoglobinuria by Krogius and von Hellens in Finland, by Theiler in 

 South Africa, in cattle in the Crimea affected with bovine malaria by Laveran 

 and Nicolle, in Argentina in the disease of cattle known as tristeza, and in 

 France in le mal de brou. 



Symptoms and lesions. Bovine piroplasmosis assumes either an acute, or a 

 subacute or attenuated form. The acute form of the disease is most common in 

 summer and is generally fatal : the temperature is raised, the urine is blood-stained 

 and often contains albumen, the animal loses its appetite and is constipated, 

 rumination is suspended, the blood becomes fluid and very pale- coloured, the animal 

 emaciates and sometimes shows nervous symptoms (delirium, paralyses) and death 

 takes place within a few days : in a small percentage of cases the animal recovers 

 but relapses are of frequent occurrence. 



The subacute form of the disease occurs more commonly in autumn and may be 

 overlooked if the blood be not examined. There is no haemoglobinuria, the fever 

 is not so marked and the symptoms are generally far less severe. 



Post mortem. In animals dead of Texas fever sub-cutaneous ecchymoses are 

 frequently found, the spleen is considerably enlarged, the perirenal tissues are 

 cedematous and the kidneys enlarged and congested : patches of pulmonary hepatiza- 

 tion are also sometimes found. Many of the red cells of the blood are enlarged and 

 their number much diminished : the leucocytes are sometimes increased in number. 



^Etiology. The researches of Smith and Kilbourne, of Koch and of Theiler show 

 that the disease is spread by ticks [Boophilus annulatus, B. dugesi, B. decoloratus^ 

 Ixodes ricinus and H cemaphysalis punctate*,]. If all the ticks be removed from an 

 animal before it is imported to a "clean" area, there is no risk of the animals in the 

 latter contracting the disease. If ticks be taken from cattle suffering from Texas- 

 fever and placed 01 pasture where healthy beasts are grazing the latter soon show 

 symptoms of the disease. The infection however is not conveyed by the tick which 

 sucked the infected blood, but by the next generation, the parasite being transmitted 

 from one generation of ticks to the next through the eggs (Smith and Kilbourne, 

 Koch and others). Female ticks after feeding on infected cattle fall to the ground, 

 lay their eggs and die : the larvae hatched from these eggs will infect the animals 

 upon which they become parasitic. 



Morphology and method of multiplication. 



1. Appearance in the blood. In almost all cases Laveran and Nicolle have 

 found the piroplasm within the red cells of the peripheral circulation in two 

 chief forms : 



1. Small, spherical or oval parasites. In stained preparations a mass of 

 chromatin generally consisting of two unequal parts the nucleus and 

 Uepharoplast can be made out, situated as a rule near the periphery of the 

 parasite. The smallest of these forms does not measure more than about 

 I//, in diameter. In the largest forms the nucleus elongates and divides into 

 two, the two parts remaining attached for a time but afterwards separating 

 and passing to the opposite ends of the parasite, after which the proto- 

 plasm divides. This represents the schizogonous asexual method of 

 reproduction. 



