498 INFECTIOUS DISEASES DUE TO PROTOZOA 



Treatment. — ^Internal medicinal treatment (arsenic, atoxyl, 

 bichlorid of mercury, intravenous injections of tartar emetic, 

 arsenophenylglycin, cacodylate of soda, etc), has been 

 tried with indifferent success in countries permanently 

 infected with dourine. In the United States no attempt to 

 treat the patients shoidd be made. All affected animals 

 should be killed. In some instances the castration of stal- 

 lions suffering from the first stages of the disease has been 

 followed by recovery. Apparently cured animals can harbor 

 virulent trypanosomes for months. All suspected and true 

 outbreaks should be promptly reported to the State authori- 

 ties. 



Surra. — Definition. — Surra is a specific, blood disease of 

 Asiatic horses, mules, camels, and dogs, due to the Trypano- 

 soma evansi, transmitted by biting insects. It is character- 

 ized by high fever (early stages), edemas of the skin, urti- 

 caria, petechise of the mucous membranes. Later the 

 patients become anemic, weak, and emaciated. 



Occurrence. — Surra exists in Asiatic countries, and is a 

 common disease in the Philippine Islands, where it affects 

 horses and occasionally carabao and cattle causing consider- 

 able losses. The disease is most prevalent in swampy dis- 

 tricts in the hot months where horse-flies abound. 



Etiology. — ^The Trypanosoma evansi, which is introduced 

 into the blood of susceptible animals by species of horse-flies 

 (Tabanus tropicus, T. lineola, Stomoxys calcitrans). Cattle 

 and zebras, which are only slightly susceptible to the disease, 

 are virus carriers. 



Symptoms. — ^The period of incubation is foiu- to thirteen 

 days. The disease begins with fever (105.8° F.), which lasts 

 four or five days, the hair coat becomes rough, the joints 

 swell, and later edemas appear under the belly and in males 

 in the prepuce. Petechise appear in the mucous mem- 

 branes (eye), followed by paleness, and in the latter stage the 

 conjunctiva presents a marked grayish-white appearance. 

 The fever usually becomes intermittent, the patient very 

 anemic and notwithstanding good appetite, loses flesh rapidly. 

 In the blood the Trypanosoma evansi is found, especially 

 in the begiiming of a febrile attack. 



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