Cause:Trypanosoma cruzi
Pathophys:
Acute form: infection of muscle fibers, glial cells, and others; after rupture, fibrosis and granulomas develop
Chronic form: autoimmune reaction leads to cardiac fibrosis; diminished ganglionic cells in gut leads to esophageal and colon dilatation
Trypanosome stage in blood ingested by reduviid (triatoma) insect, multiply in insect's gi tract into metacyclic stage. Bug infected for life, no vertical transmission; metacyclic stage in feces near bite, enters wound or transferred manually by host to eye and elsewhere; multiplication only in intracellular form, which then ruptures, leading to trypanosomes in blood
Animal (rodent) reservoirs. Central and South America. Rarely via blood transfusion (Ann IM 1989;111:849, 851) or congenital if placental defect
Acute form in children; chronic in adults who had acute form in past
Sx:
Acute: fever
Chronic: CHF, gi sx of megaesophagous and megacolon
Si:
Acute: hepatosplenomegaly, lymphadenopathy. Chagomas = local tissue swelling in skin, esp in children. Unilateral eye swelling (Romaña's si)
Chronic: CHF, heart block, angina, Vtach, or other cardiac involvement in 30-40% eventually
Acute: encephalitis, asx CNS disease common; myocarditis, r/o Chagas' whenever any appropriately exposed pt has ischemic heart disease or dilated cardiomyopathy
Chronic: recrudescence w immunosuppression
Lab:
Bact:Acute: culture from blood or tissue on NNN (type of blood agar)
Hem:Acute: organisms in peripheral smear, esp buffy coat; prominent kinetoplast; undulating membrane. Chronic: no organisms
Noninv: Thallium ETTs and EKGs appear like MIs
Path:Chronic: organisms in tissue sections in only 25%
Serol:Acute: comp-fix titer elevated but hemagglutination titer increased 1st.
Chronic: IgG ELISA titer
Rx:None very good; nifurtimox (Rev Infect Dis 1986;8:884) 8-10 mg/kg/d po divided qid × 120 d; alternative, benznidazole 5 mg/kg qd × 30 d (ann IM 2006;144:724)