332 PARASITES OF THE DOMESTIC ANIMALS 



Surra 



This name has been given to a disease of horses, camels, and dogs of 

 Asia caused by Trypanosoma evansi, which in 1880 was found by Evans 

 in the blood of affected horses. Surra occurs in Southern Asia, the 

 East Indies, the Philippines, Korea, Australia, and among the drome- 

 daries in Northern Africa where it is known under the name of mbori. 



Symptoms. — In its constant and progressive anaemia and cachexia 

 the disease closely resembles nagana. At its outset there is a rise of tem- 

 perature which in some cases may be followed by an urticarial eruption. 

 Edema appears under the skin of the belly and limbs, and the eyelids 

 become puffy with conjunctiva congested. The appetite is usually re- 

 tained, but in spite of this there is loss of flesh and strength. Later the 

 appetite is lost, there is great weakness, and the wasted and enfeebled 

 animal may fall and be unable to again get upon its feet. 



Course. — Horses invariably die in from one to several months after 

 the onset of the disease, though in some cases death may occur suddenly 

 in the early stages. In camels the disease runs a much longer course. 

 Cattle, though they may harbor the parasites in their blood, generally 

 resist the disease. 



Infection. — A specific carrier of the organism causing surra is not 

 known. Tsetse flies are not found in Asia, but it has been determined 

 that the stable fly {Stomoxijs calcitrans) and the horsefly (Tabanus stri- 

 atus) of Asiatic countries can transmit the disease by their bite. It is 

 believed by some that the horsefly is the principal carrier. So far as 

 known the flies carry the disease from animal to animal directly by means 

 of contaminated mouth parts, and are unable to infect for more than 

 one or two days after having drawn the blood of an infected animal. 



Mal De Caderas 



Mai de caderas (disease of the hip) is a trypanosomiasis occurring in 

 horses throughout the greater part of South America, caused by Ti^y- 

 panosoma equinum, which was discovered by Elmassian in the blood of 

 horses in Argentina in 1901. The occurrence of the disease by natural 

 infection is almost exclusively among horses and mules, the former of 

 which are the more susceptible. A number of other mammals may be 

 successfully inoculated, among them the hog, rabbit, guinea pig, rat, and 

 mouse. 



Symptoms. — Following a statement that, owing to its great ravages 

 in certain parts of South America, cattle have to be used for riding purpo- 

 ses, Laveran and Mesnil (Trypanosomes and Trypanosomiases, Eng- 

 hsh edition) describe the symptons of the disease as follows : 



"The first sign of the disease in horses is wasting, which rapidly pro- 



