Final answer:
In sleeping sickness and Chagas disease, humans are infected with the trypanosome hemoflagellate in its trypomastigote developmental stage.
Step-by-step explanation:
In sleeping sickness and Chagas disease, humans are infected with the trypanosome hemoflagellate in its trypomastigote developmental stage. In sleeping sickness, caused by Trypanosoma brucei, the parasite is transmitted to humans by the bite of the tsetse fly. In Chagas disease, caused by Trypanosoma cruzi, the parasite is transmitted to humans through the feces of triatomine bugs.