Trypanosome infections cause African sleeping sickness and South America's Chagas' disease, which often produces fatal heart damage. The parasite (1) enters the blood following a bite by an infected insect such as an assassin bug or tsetse fly; it reproduces (2) and develops into forms that can be ingested by other bugs (3). In these bugs, intermediate forms (4) develop into parasites to infect more people.
A trypanosome is a protozoan responsible for trypanosomiasis of the African (sleeping sickness) and South American (Chagas' disease) varieties, carried by the tsetse fly and certain bugs respectively. Trypanosomes are relatively insensitive to chemotherapy in established cases; prevention is therefore important.