ETIOLOGY 423 



a 



MAL DE CADERAS 



§ 325. Characterization. Mai de caderas (disease of 

 the rump) is a disease essentially of the horse kind, charac- 

 terized by an intermittent fever, a progressive paralysis of the 

 posterior parts, rapid emaciation and death. It is a "wet 

 weather" disease, as it is reported to almost entirely disappear 

 in the dry season. Horses, mules and asses are said to suffer 

 from it. Horses are said never to recover. 



§ 326. History. Rebourgeon studied this disease in 

 1889. He made a bacteriological investigation into its cause 

 without success. Leclerc described it clinically in 1899. He 

 believed that he had found its pathogenic bacterium. In 

 1901, Elmassian showed that this disease was caused by one 

 of the trypanosoraa. \^oges and Lignieres confirmed his 

 disco ver}-. 



§ 327. Geographical Distribution. Mai de caderas is 

 a disease of tropical South America. 



§ 328. Etiology. Elmassian differentiated the try- 

 panosoma of this affection in 1901. Voges pointed out its 

 pathogenic action and named it TV. equiniim. In length it is 

 3 or 4 times the diameter of the red blood corpuscles. Its 

 width is one-third to one-half the diameter of a red blood cell. 



The anterior end is provided with a fiagellum about as 

 long as the body of the parasite. It extends backward about 

 two-thirds the length of the body as a somewhat thickened 

 margin of a distinct undulating membrane. The posterior end 

 of the parasite is about one-third the length of the fiagellum. 

 It is contracted and somewhat beak shaped. 



Its motion resembles that of an eel, but its actual motility 

 is not great, the whole body taking part in an excessively 

 active wriggling motion with the fiagellum and beak ends 

 moving in opposite directions. The nucleus is toward the 

 anterior end, a very small centrosome near the posterior end, 

 and there is a granular protoplasm. 



It is found in the blood of horses, mules, asses, hogs and 



