456 INFECTIOUS DISEASES DUE TO PROTOZOA 



treat the patients should be made. All affected animals 

 should be killed. In some instances the castration of stallions 

 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 authorities. 



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

 Asiatic hoxses, 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 four 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. Petechia? 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 beginning of a febrile attack. 



Course. — The course is usually one or two months, rarely 

 does death ensue in one or two weeks. 



Prognosis. — Bad. Nearly all cases die. 



Treatment. — In permanently infected districts, arsenic 

 (gr. x-xv daily for ten days in powder form as a bolus or 

 electuary) has given good results. Atoxyl (Bj-v of a 4 



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