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This question is likely not important for two reason:
They're both Trypansomastigotes, so of course they look almost the same.
You can differentiate these two species clinically as they have very little clinical similarity in patient presentation.
For these reasons there's little to no reason you would be expected to differentiate these two species by histology alone
Does Chagas have recurrent fever? Because that's what pointed me to African Sleeping Sickness.
The history of travel to the Amazon is what pointed me to Cruzi over Brucei but agree it's a tough distinction to make here. In the absence of that detail I would have probably picked Tsetse fly.