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American trypanosomiasis, or Chagas disease, is a zoonotic illness caused by the parasite Trypanosoma cruzi.

A triatomine bug ingests the trypomastigotes of the parasite when it feeds on the blood of an infected human host.

Inside the insect’s midgut, the trypomastigotes transform into epimastigotes and multiply by binary fission.

They then migrate to the hindgut and differentiate into the infective metacyclic trypomastigotes.

When the insect takes another blood meal, it defecates near the bite site, releasing parasites in its feces onto the skin.

Scratching the bite site allows the parasites to enter through the wounded skin.

After entering the host, trypomastigotes invade cells near the site of infection and transform into intracellular amastigotes.

The amastigotes multiply by binary fission and accumulate in the host cell cytoplasm to form clusters known as pseudocysts.

These amastigotes eventually convert back into trypomastigotes, rupture the host cell, and are released into the bloodstream, ready to be taken up by another bug.