748 PATHOGENIC PROTOZOA 



Treatment, including the use of arsenical preparations, is without 

 effect, and all infected animals should be destroyed. 



The disease is apparently transmitted directly by flies, which carry 

 blood and serum from ulcers and abrasions on infected to healthy 

 animals. 



Morphology of the Parasite. The trypanosome is sixteen to eight- 

 een microns long and two microns wide. The kinetonucleus is about 

 two microns from the posterior end, the trophonucleus about eight to 

 ten microns from the same point. The posterior end is blunt and the 

 cytoplasm usually contains numerous basophile granules; the undu- 

 lating membrane is well developed and a chromatin filament runs from 

 the kinetonucleus to the tip of the flagellum. The large kinetonucleus 

 distinguishes this organism from Trypanosoma equinum. 



Pathological Anatomy. Aside from the emaciation, edema of the 

 belly wall, conjunctivitis and subconjunctival ecchymosis, there is usu- 

 ally excessive fluid in the body cavities, an enlarged spleen, and, what 

 is more characteristic, small petechial spots on the capsule of the 

 spleen and in the cortex of the kidney and in the endo- and pericar- 

 dium and occasionally on the pleural surfaces. 



Prophylaxis consists in the destruction of all infected animals ; the 

 protection of wounds and ulcers in otherwise healthy animals by dress- 

 ings and, wherever possible, the use of fly screens about the stables. 



Trypanosoma equiperdum (Dourine). This organism is the cause 

 of dourine, a disease of horses and donkeys, which is usually trans- 

 mitted by coitus, but may be carried by biting flies, stomoxys. The 

 organism was first described by Rouget in 1894 ; it resembles brucei in 

 many ways and produces a progressive, fatal disease of great economic 

 importance. Formerly it was present throughout the greater part of 

 Europe, but is now almost limited to the shores of the Mediterranean. 

 From time to time it has been introduced into the United States and 

 Canada by blooded French stallions and has spread into parts of the 

 Northwest. 



The clinical course may be divided into a stage of edema, lasting 

 about a month, during which there is a painless, soft swelling, limited 

 to the genitalia and the belly wall. This is followed by the stage of 

 eruption, during which plaques, or round edematous areas, are found 

 under the hide on the flanks and hind quarters, and sometimes on 

 thighs, shoulders and neck; this stage is short, lasting about a week. 

 It is followed by the third stage of paralysis and anemia ; the animal 

 loses flesh and strength, develops superficial ulcers, conjunctivitis, 



