596 PIROPLASMOSIS OF HORSES 



in couples are, however, also seen. Romanowski's stain shows a 

 red-stained chromatin granule near the periphery of the parasites; 

 pigment (as in malarial parasites) is never seen. Laveran described 

 amitotic division of the nucleus; two divisions may follow each other 

 rapidly, so that four parasites arranged in rosette form may be seen 

 in a red blood corpuscle. The most prominent changes in equine 

 piroplasmosis are intense jaundice, with enormous enlargement of 

 the spleen, which may weigh ten pounds or more. The pulp of the 

 spleen is very soft, dark, and tar-like. The bladder contains hemor- 

 rhagic urine. Subserous and submucous hemorrhages are frequently 

 seen; the heart muscle is very soft and flabby, and ruptures easily. 

 The disease is spread, like the other piroplasmoses, by ticks. 



QUESTIONS 



1. What kind of a disease is Texas fever? 



2. What other names have been given to this disease? 



3. What were the claims of Babes as to the nature and cause of the disease? 



4. What is the real cause of Texas fever? Who discovered it? 



5. Describe the pathologic changes in a very acute case of Texas fever. 



6. What are the blood changes in Texas fever? 



7. What is the meaning of the terms oligocythemia and oligochromemia ? 



8. How can an absolute diagnosis of Texas fever be made? 



9. Describe the steps in a blood examination for establishing a diagnosis of 

 Texas fever. 



10. Describe the morphology of the Piroplasma bigeminum. 



11. What is the relation between the parasites and febrile temperatures in 

 infected animals? 



12. Where are the piroplasmata found most numerous after the death of an 

 infected animal? 



13. How long does blood infected with piroplasmata remain virulent under 

 various conditions? 



14. Describe the cultural properties of Piroplasma bigeminum and the prepar- 

 ation of the proper culture medium. 



Li 15. What is the natural mode of transmission in Texas fever? 

 ""* 16. What animals are susceptible to this disease? 

 3f 17. How can the disease be transferred artificially? 



' 18. What are the technical names of the Texas fever cattle tick? Describe 

 its life history. 



19. What methods have been practised to immunize cattle against Texas 

 fever? 



20. Describe in detail the Louisiana method. 



21. When is the best time to immunize animals against Texas fever? 



22. What animal is the host of Piroplasma canis? Describe the morphology 

 of the latter. 



23. Describe its method of reproduction. 



24. Discuss the different views as to processes of reproduction in Piroplasma 

 canis. 



25. What is the most constant symptom in piroplasmosis of dogs? 



26. How is the disease spread? 



27. What difference in the mode of spreading is there between piroplasmosis 

 of dogs and Texas fever? 



28. Describe the most prominent pathologic changes of ictero hematuria in 

 sheep. What is the cause of the disease ? 



29. What are the most prominent pathologic changes in piroplasmosis of 

 horses? Where has the disease been observed? 



