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a genus of protozoans of the class Flagellata that parasitize the blood and tissues of vertebrates, including man. There are several dozen species, many of which are pathogenic. The body is spindle-shaped and has a single nucleus. The flagellum originates in the cytoplasm of the posterior third of the body from the basal corpuscle. It protrudes freely and forms an undulating membrane with the fold of the pellicle. Alongside it is a kinetoplast, a mitochondrion-like organelle that abounds in DNA. Members of the genus reproduce by longitudinal division. There is no sexual process. Most species penetrate into the body of a vertebrate animal or man through transmitters, usually in-sects. The insects either transmit the parasites mechanically with their piercing mouth parts or serve as temporary hosts to the parasites, which reproduce and undergo a succession of morphological changes, becoming crithidiae and leptomonae.
T. gambiense and T. rhodesiense are pathogenic for man; they cause African sleeping sickness, transmitted by flies of the genus Glossina. T. evansi (the causative agent of surra) and T. brucei (the causative agent of nagana) parasitize cattle in Africa and India. In the USSR, camels suffer from su-auru, caused by T. ninaekohlyakimovi, and horses and donkeys suffer from dourine, caused by T. equiperdum.
IU. I. POLIANSKII