TRYPANOSOMA 359 
1843 to 1879 the organisms were found by many observers, not only 
in frogs but in birds as well. 
In 1879-80, Lewis described trypanosoma found in rats in India. 
Later he states that they are identical with Tr. evansi. 
In 1880, G. Evans discovered trypanosoma in the blood of horses 
suffering with surra, the well known disease of India. He proved 
their causal relation to the affection. In 1885, Steele confirmed 
Evans’ work, and named the parasite Spirocheta Evansi. 
The work of Evans and Steele was followed by many interesting 
discoveries of trypanosoma especially in fish and in man. 
In 1896, Rouget described Trypanosoma found in the blood of a 
horse suffering from dourine. Wasilewsky and Senn, in 1899, 
confirmed Rouget’s work and determined the pathogenic action of 
this parasite for the horse. Laveran and Mesnil proposed the name 
Tr. rougeti for the parasite of dourine. Doflein (July, 1901) named it 
Tr. equiperdum, which term was adopted by Salmon and Stiles. 
In 1901, according to Voges, Elmassian first differentiated the 
trypanosoma of Mal de caderas in South America. Voges described 
it the following year, demonstrated its pathogenic action, and named 
it Tr. equinum. 
