. Animal parasites and human disease. Insects as carriers of disease; Medical parasitology. 94 TliVPANOSOIMES AND SLEEP1N(J SICKNESS Rhodesia in southeastern Africa occasioned by a distinct and ap- parently newly orij^inated type of trypanosonie, as indicated b}' its sudden appearance and startlingly rapid spread. This type of sleeping sickness is more deadly than the older type and there is reason to fear that unless efficient methods of control- ling it and stamping it out are discovered it will spread over a large part of tropical Africa. The disease has already spread over a great part of
. Animal parasites and human disease. Insects as carriers of disease; Medical parasitology. 94 TliVPANOSOIMES AND SLEEP1N(J SICKNESS Rhodesia in southeastern Africa occasioned by a distinct and ap- parently newly orij^inated type of trypanosonie, as indicated b}' its sudden appearance and startlingly rapid spread. This type of sleeping sickness is more deadly than the older type and there is reason to fear that unless efficient methods of control- ling it and stamping it out are discovered it will spread over a large part of tropical Africa. The disease has already spread over a great part of Rhodesia, Nyasaland and Portugese East Africa, and has been reported from German East Africa. There is apparently a rather high natural immunity to the disease, which alone is responsible for the small number of the victims. In the same year, 1909, a fever caused by a trypanosome was dis- covered by Chagas in tropical Brazil, and has since been found to be widely distributed there, and to be the cause of much of the non-malarial " fever " for which the jungles of tropical South America are famous. The Parasites. — The trypano- somes, next only to the malarial parasites, may be considered man's most deadly enemies among the Protozoa. Like the Leishman lK)dics described in the preceding chapter, they are members of a primitive group of the class Flagel- lata, but of somewhat higher or- ganization, and probably higher in the scale of evolution. Trypano- somes are very active, wriggling little creatures somewhat suggest- ing diminutive " artistic dolphins " (Fig. 17). They are about 25 n (al)out tAs of fi» inch) or even less in length, spindle-shaped, and somewhat flattened from side to side like an eel. Along the " back" runs a flagellum connected with the body by an undulating mem- brane, like a long fin or crest. This terminates at what is really the anterior end in a free tail-like flagellum. It is by means of the wave motions of the membrane an
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmedical, bookyear1918
