trypan

Trypan is a shorthand term that may refer to two distinct topics in biology and medicine: Trypanosoma, a genus of parasitic protozoa, and trypan blue, a vital dye used in microscopy to assess cell viability.

Trypanosoma comprises flagellated, single-celled parasites in the family Trypanosomatidae. They are kinetoplastids transmitted by insect vectors. Notable species include Trypanosoma brucei, which causes African sleeping sickness and is transmitted by tsetse flies, and Trypanosoma cruzi, which causes Chagas disease and is spread by triatomine bugs. The parasites have complex life cycles alternating between insect vectors and mammalian hosts, with forms such as bloodstream trypomastigotes in mammals and procyclic or epimastigote forms in insects. Diagnosis relies on microscopy, serology, and molecular methods. Treatments, when available, vary by species and disease stage and may involve antiparasitic drugs, with supportive care for complications.

Trypan blue is a synthetic aniline dye used as a vital stain in microscopy. It is excluded by viable cells with intact membranes but is taken up by dead or damaged cells, allowing viability assessment. In routine practice, equal volumes of cell suspension and 0.4% trypan blue are mixed, incubated briefly, and then counted on a hemocytometer to distinguish unstained (live) from blue-stained (dead) cells. It is widely used for assessing cultured mammalian cells, yeast, and other cell suspensions prior to experiments or transplantation. Limitations include inability to distinguish late apoptosis from necrosis and potential underestimation of viable cells under some conditions.