SURRA." 



By Ch. Wardell Stiles, Ph. D., 



Consulting Zoologist, Bureau of Animal Industry; Zoologist, United States Public Jlealth 

 and Marine-Hospital Service. 



Surra is not known to occur in the United States.; but it is more or 

 less common in the Philippine Islands and India. It is caused by a 

 microscopic, flagellate animal parasite, known as Trypanosoina Evann't., 

 20 to 30 yw long by 1 to 2 ;< broad, which liv^ es in the blood and destro\'s 

 the rod-blood corpuscles. In general, the disease is very similar to, 

 and belongs in the same general class with, tsetse-fly disease, or nagana, 

 of xVfrica and mal de caderas of South America. 



CLIMATIC CONDITIONS. 



Surra is a wet weather disease, occurring chiefly during or imn)e- 

 diately after heavy rainfalls, floods, or inundations. 



ANIMALS AFFKCTED. 



Surra attacks especially horses, asses, and mules, but it may occur 

 in kerabau, camels, elephants, cats, and dogs, and has been transmitted 

 to cattle, buffaloes, sheep, goats, rabbits, guinea pigs, rats, and mon- 

 keys. No birds, reptiles, amphil)ia (frogs, etc.), or fish are known to 

 suffer from it. It attacks both male and female animals, young and 

 old. Australian breeds of horses and white and gray mules are said 

 to be more susceptible than animals of other breeds and color. 



LETHALITY— DURATION. 



Surra in equines and camels is said to be an invariabh^ fatal disease, 

 but cattle occasionall}' recover from it. There is no histoiy of a 

 definite onset of the disease, and the condition is progressive, usually 

 with a number of relapses. The period of incubation may vary some- 

 what; in experimental cases it is from two to seventy-five (usually six 

 to eight) days, according to conditions. The duration varies with tlio 

 species of animal attacked, their age, and general condition. Th. 

 average duration in the horse is reported as less than two months, 

 though some cases may terminate fatalh"" 'n less than one to two weeks. 



« For a more detailed discussion of this disease see Salmon & Stiles, 1902, Emer- 

 gency report on surra <Bul. 42, Bureau Animal Industry, U. S. Dept. Agric, 

 Wash., pp. 1-152, figs. 1-112. Eeprinted in Eighteenth Annual Report (for 1901), 

 Bureau of Animal Industry, pp. 41-182, figs. 1-112. 

 546 



