Trypanosoma cruzi

Trypanosoma cruzi - a species of parasitic euglenoid protozoan in the family trypanosomatidae.

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Risk factors

The triatomine bug thrives in poor housing conditions (for example, mud walls, thatched roofs), and where the bug is present, people living in rural areas are at greatest risk for getting infected.

Transmission

• T. Cruzi is passed between mammalian hosts through the feces of a triatomine insect vector.

Steps in transmission

• An infected triatomine insect vector (or “kissing bug”) takes a blood meal and releases trypomastigotes in its feces near the site of the bite wound.
• Trypomastigotes enter the host through the wound or through intact mucosal membranes, such as the conjunctiva
• Common triatomine vector species for trypanosomiasis belong to the genera Triatoma, Rhodnius, and Panstrongylus.
• Inside the host, the trypomastigotes invade cells near the site of inoculation, where they differentiate into intracellular amastigotes
• The amastigotes multiply by binary fission and differentiate into trypomastigotes, and then are released into the circulation as bloodstream trypomastigotes
• Trypomastigotes infect cells from a variety of tissues and transform into intracellular amastigotes in new infection sites
• Clinical manifestations can result from this infective cycle. The bloodstream trypomastigotes do not replicate (different from the African trypanosomes)
• Replication resumes only when the parasites enter another cell or are ingested by another vector.
• The “kissing bug” becomes infected by feeding on human or animal blood that contains circulating parasites
• The ingested trypomastigotes transform into epimastigotes in the vector’s midgut
• The parasites multiply and differentiate in the midgut and differentiate into infective metacyclic trypomastigotes in the hindgut

Other modes of transmission

• Trypanosoma cruzi can also be transmitted through blood transfusions, organ transplantation, transplacentally (from mother to unborn baby), and in laboratory accidents.

Pathogenesis

• Infection in humans causes chagas disease.
• It is found only in the Americas, mainly, in rural areas of Latin America where poverty is widespread.
• Chagas disease is common in parts of Mexico, Central America, and South America where an estimated 8 million people are infected.

Other names

Chagas disease (T. cruzi infection) is also referred to as American trypanosomiasis.

Also see

• Chagas disease
• Trypanosomiasis