TRYPANOSOMA 487 



impart immunity, and that in this way it may be possible to secure pro- 

 tection against the ravages of nagana. 



In 1896 Rouget discovered a trypanosome in the blood of bleeding 

 equines in Algiers and South Africa affected by the disease called 

 Dourine. Some authors think this disease is identical with nagana 

 and surra, but the fact that it has been impossible to infect cattle with 

 the blood of the sick equine point to its being a distinct disease. The 

 trypanosoma is called trypanosoma equiperdum or trypanosoma Rougeti. 



Recently, mal de caderas, a disease of horses, asses, and mules in 

 South Africa, having the general characteristics of trypanosomiasis, 

 has been shown by Voges to be due to trypanosornes. He called 

 this organism trypanosoma equinum, and believes it to be a dis- 

 tinct species, resembling more closely the trypanosoma Lewisi. He 

 considers cattle immune. 



In 1902 Laveran described a variety of trypanosome found by Theiler 

 to produce disease in ruminants of the Transvaal. According to 

 Laveran and Mesnil it is characterized by having the "flagellum root" 

 near the centre of the parasite, near and sometimes united to the nucleus. 

 This variety has been named trypanosoma Transvaaliense, while 

 another variety found in cattle of South Africa by Theiler, and pro- 

 nounced by Laveran and Mesnil to be a distinct species, was named 

 trypanosoma Theileri. 



Trypanosomes have been found in the blood of apparently normal 

 frogs, fishes, birds, guinea-pigs, rabbits, and bats. No relationship has 

 been shown to exist between these non-pathogenic forms and those 

 causing disease in the higher animals. 



Trypanosomes in Man. 



In 1898 Nepvieu reported having found trypanosomes in the blood of 

 6 out of more than 200 cases examined for malarial organisms. In all 

 of these cases malarial organisms too were found, and no symptoms char- 

 acteristic of the invasion of trypanosomes were observed. Nepvieu found 

 flagellates in a seventh case which was apparently in good health. 



The eighth case is reported by Dutton in 1901. This case was a 

 European who had lived some years in AVest Africa. The principal 

 symptoms were gradual wasting and weakness; irregular temperature, 

 never very high and of a relapsing type ; local oedemas, congested areas 

 of the skin, enlargement of the spleen, and constant increased frequency 

 of pulse and respiration. It ended fatally after one year and eight 

 months. The chronic character was repeated in animals. Some white 

 rats were refractory; others died in two to three months. In monkeys 

 (Macacus rhesus) it was fatal in about two months. Dogs were un- 

 affected. This trypanosome is distinctly smaller than the other species 

 described, and there is little doubt of it beinir a distinct species. Dutton 

 also found trypanosomes in the blood of 1 out of 150 apparently healthy 

 Gambian children examined by him. 



The tenth case is published by Manson in 1902. This was a mis- 



