Monomorphic Trypanosomes.
A number of trypanosomes, characterized by relative uniformity in size and structure, may be considered under this heading. They occur in cattle, sheep, goats and horses in Africa, especially West Africa. Morphologically, they are characterized by the posterior (aflagellar) part of the body being swollen, while the anterior part narrows. The nucleus is central and situated at the commencement of the narrowing of the body. The blepharoplast is almost terminal, the undulating membrane is narrow and not markedly folded, so that the flagellar border lies close to or along the body. The flagellum may or may not possess a free portion.
Some recent workers have considered that T. brucei (Zululand strain) and T. evansi are also monomorphic, but they do not exhibit the general characteristics outlined above. T. brucei and T. evansi have already been considered separately.
The monomorphic trypanosomes, as defined above, include:—
Trypanosoma vivax, Ziemann, 1905.
Fig. 45.—Trypanosoma vivax. × 2,000. (Original. From preparation by Fantham.)
This trypanosome[109] occurs in cattle, sheep and goats, and was first found in the Cameroons. It is fatal to cattle. Equines are also affected. Antelopes are the possible reservoirs of the trypanosome. It is probably transmitted by Glossina palpalis and other tsetse flies. Its movement is very active. It possesses a free flagellum (fig. 45) and it averages 23 µ to 24 µ in length. T. cazalboui (Laveran, 1906)—the causal agent of “souma” in bovines and equines in the French Sudan—is probably synonymous with T. vivax.
Trypanosoma capræ (Kleine, 1910) is allied, but is somewhat broader and more massive. It was found in goats in Tanganyika.