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DISEASES OF THE DOMESTIC ANIMALS 



Surra. 



This is a febrile disease produced by a protozoon, Trypan- 

 osoma evansi, in the blood plasma, and attacks horses, asses, mules, 

 camels, dogs, goats and very rarely cattle. It is indigenous in 

 India. 



The trypanosoma is a protozoon, 20 to 50 m. long, and 1 to 

 1.5 m. wide, with a single flagellum attached to an undulating mem- 

 brane. The parasite appears to gain entrance to the body through 

 green fodder and water and in grain contaminated with mice or 

 bandicoot rat feces. Also by inoculation of the skin through the 

 medium of the tsetse fly, and perhaps by means of lice, fleas and 

 ticks. 



Symptoms. — The disease occurs in the fall, from September to 

 December, and in animals fed from grass raised on low-lying and 

 flooded meadows. The period of incubation is variable ( from six to 

 seventy-five days) and somewhat dependent upon whether the 

 disease has been inoculated (short incubation) or ingested. The 

 average duration is about fifty-two days. The termination is gen- 

 erally fatal without treatment. 



Irregular, remittent or intermittent fever is characteristic. 

 During the remissions the protozoa can not be found in the blood 

 but are present during the paroxysms. Urticaria and edematous 

 swellings on dependent parts — lip, legs, sheath and belly — are seen, 

 Petechiae appear on the mucous membranes, particularly on the 

 membrana nictitans in the horse, and lachrymation is present. Pro- 

 gressive weakness, emaciation and anemia, with often icterus of the 

 mucous membranes, are characteristic. The lymphocytes increase 

 in the blood, while hemoglobin is diminished and rouleau formation 

 of the red corpuscles is lost. 



Tsetse Fly Disease, Trypanosomatosis or Nagana, due to 

 Trypanosoma brucei, which is prevalent in Africa and is largely 

 inoculated by the tsetse fly, is very similar and many authorities 

 (Koch) claim it to be identical with surra. But in nagana cattle are 



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