Development and life cycle of Trypanosoma cruzi in insect vector reduviid bugs.
Trypanosoma cruzi is a parasite belonging to Hemoflagellates group.
Development of Trypanosoma cruzi ininvertebrate host, that is Reduviid bugs starts with ingestion of broader less motile trypomastigote forms that are present in blood of infected vertebrate human host, are transmitted to reduviid bugs during the blood meal.
Trypomastigote forms transform into amastigote forms in the foregut, that is stomach.
Further amastigote transforms into epimastigote and spheromastigote forms. Some intermediate form of parasites is destroyed in foregut.
Epimastigotes passes in gut further to the midgut or intestine. Epimastigotes forms multiply by binary fission and attaches to the gut epithelial lining. This attachment to the epithelial cells is due to presence of flagellum of epimastigote form.
Further the epimastigote form travel to the hindgut, that is rectum.
They finally transform into metacyclictrypomastigote forms in the hindgut. Metacyclic trypomastigote attaches to the cuticle lining of rectum and rectal sac of insect.
When bug or insect passes feces or urine these metacyclic trypomastigote forms are excreted in feces or urine.
On subsequent insect bite metacyclic trypomastigote forms infects new vertebrate host and again starts life cycle in vertebrate host.
This whole insect cycle takes about 10 to 15 days. That is called as extrinsic incubation period.
There is no transovarian transmission seen in the reduviid bugs and once infected, they retain the infection throughout the life by the molting cycles.
