564 FAMILY: TRYPANOSOMID^ 



Possibility of T. vivax Infecting Man. — An observation of Macfie 

 (19176) is of considerable interest in connection with this trypanosome. 

 He discovered in two blood-films made on two occasions from a native 

 of the Gold Coast a trypanosome which morphologically resembled 

 T. vivax. Of 200 trypanosomes measured, the longest was 24 microns and 

 the shortest 18 microns, giving an average of 20-7 microns. The organism 

 was evidently monomorphic, and completely unlike the ordinary T. gam- 

 biense of this district. Furthermore, it had the swollen and rounded 

 posterior end of T. vivax, and large terminal or nearly terminal kinetoplast. 

 As T. vivax is exceedingly common in domestic animals in West Africa, 

 the author, having demonstrated its presence in 76 per cent, of the hump- 

 backed cattle of Accra, it is possible that in this case T. vivax, usually not 

 inoculable to man, has been able to obtain a footing in a human host. 

 Macfie is inclined to regard the infection as actually one of T. vivax in man. 

 Should this conclusion be confirmed, it is of interest in the light of the 

 much-disputed relationship of T. brucei and T. rhodesiense, where again a 

 trypanosome which is readily inoculable to domestic animals may only infect 

 human beings under exceptional circumstances. It, furthermore, raises the 

 question of the possibility of other trypanosomes infecting human beings. 



Possibility of T. vivax occurring in South America. — Leger, M. and 

 Vienne (1919) discovered a trypanosome in cattle in Venezuela, which 

 they named T. guyanense. As this name was already pre-occupied 

 (Mesnil, 1912), Lavier (1921) proposed to substitute the name T. viennei. 

 As regards its morphological characters and the susceptibility of laboratory 

 animals, it resembled T. vivax of Africa. Tejera (1920rt) studied the 

 organism, and thought it possible that it was actually T. vivax which had 

 been introduced from Africa some years before. If this view is correct, it 

 is remarkable that the trypanosome should have established itself in South 

 America, where the tsetse fly, the natural vector of T. vivax, does not occur. 



Trypanosoma caprae Kleine, 1910. — This trypanosome was first 

 studied by Kleine (1910) near Tanganyika, and was afterwards investigated 

 by Bruce et al. (1913/) in Nyasaland. It is a very actively motile trypano- 

 some, like T. vivax, which it resembles closely (Fig. 232, A, and Plate V., e, 

 p. 456). It is, however, more heavily built, has a larger and more clumsy 

 appearance, and varies in length from 18 to 32 microns, with an average 

 of 25-5 microns. Measured across its broadest part, which, as in T. vivax, 

 is posterior to the nucleus, it is found to vary in breadth from 1-75 to 4-35 

 microns, with an average of 3 microns. The undulating membrane is 

 broader than in T. vivax, and there is a fiagellum 4 to 9-5 (average 6-5) 

 microns in length. It occurs in cattle, sheep, and goats, which may 

 recover from their infection. It is not inoculable to small animals in the 

 laboratory. 



