a parasitic protozoan (single-celled animal) that moves by means of whiplike structures and can infest the blood, causing sleeping sickness and other diseases

any of a genus of parasitic protozoans (minute single-celled animals; see protozoan) that move by means of whiplike structures. Usu transmitted through insect bites, they can infest the blood of various vertebrate animals, including human beings, causing serious diseases: genus Trypanosoma