Trypanosoma cruzi (Chagas disease)

^[1]^[2]

Epidemiology

United States, Central & South America rarely, cases orginate in United States
transmitted by kissing bugs of the family Reduviidae, so named because it often bites the face
bug defecates at the time of biting
bug feces contain infective trypomastigotes that penetrate the skin as a result of scratching or rubbing or through intact mucosa
infection may be transmitted by blood transfusion
vertical transmission from mother to baby
dogs, rodents, armadillos, & other domestic & wild animals serve as reservoirs

after gaining access to tissues, typomastigotes transform into dividing amastigotes
when the infected cell is full of amastigotes, transformation to trypomastigotes occurs, followed by cell rupture
trypomastigotes are released into the peripheral blood where they reach distant tissues & begin the replicative cycle again
cross-reactivity of Trypanosoma cruzi antigens with human protein(s) <see serology>
- R1 & R3 epitopes of TCFL5, recognized by T- & B-cells, respectively

Trypanosoma identified in isolate
- diagnosis is made by demonstration of trypomastigotes in blood, buffy coat or aspirates of lymph nodes or chagomas
- trypomastigotes
  - curved with S & C shapes
  - measure up to 20 um in length
  - kinetoplast larger than that of T brucei
Trypanosoma identified by culture
Trypanosoma cruzi DNA
Trypanosoma cruzi serology:
- EIA, IFA & ELISA are available
- false positives may occur in patients with Leishmaniasis
- antibodies against TCFL5 (nuclear antigen)
xenodiagnosis in endemic areas
- examination of the gut contents of laboratory-raised rejuviid bugs that have been allowed to feed on the victim
see ARUP consult^[2]

↑ Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 1266
↑ ^2.0 ^2.1 ARUP Consult: Trypanosoma cruzi - Chagas Disease The Physician's Guide to Laboratory Test Selection & Interpretation https://www.arupconsult.com/content/trypanosoma-cruzi