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Chagas disease


-most important parasitic infection in the Western hemisphere

-transmitted by triatomine bugs (bite or oral ingestion of contaminated food), blood transfusion or transplantation; confined in Americas (North to South)

-Chagas disease; cardiomyopathy can occur in 20-30% of patients; infection is lifelong unless treated; pathognomonic: apical aneurysm

-pathogenesis: infection with immune response and auto reactivity. Secondary mechanisms: neurogenic disturbance and microvascular derangements

-acute infection (detected by parasitemia): non-specific febrile syndrome; chagoma (skin nodule) or Romana's sign (eyelid edema) may occur; in severe acute cases, meningoencephalitis and myocarditis can occur; can detect parasites in blood smears

-stages:acute infection, chronic (indeterminate, cardiac, digestive, mixed)

-chronic infection: earliest sign is conduction system abnormalities (RBBB and left hemlock) -> dilated CMP -> CHF

-GI Chagas: esophagus, colon

-cardiac Chagas is more common than GI Chagas. <10% of acute infection progress to chronic infection

-In immunocompromised hosts, reactivation can be severe: In HIV patients, reactivation most commonly presents as meningoencephalitis or abscess, followed by acute myocarditis; in patients who underwent heart txp for Chagas CMP, Chagas should be in the differential of patients with fevers and rejection crises

- in immune compromised patients, they can get Chagas encephalitis/meningitis

- oral ingestion is associated with acute myocarditis

-dx: finding trypomastigotes in smear for acute infection; IgG for chronic infection (preferably with 2 tests), EKG and 30-second rhythm strip. For acute infection and for transplant recipient workup, do PCR. Also use PCR in patients with chronic infection suspected to have reactivation.

-rx: Nifurtimox (GI and neuro side effects) and benznidazole (1st line; can cause rash, marrow suppression and neuropathy; also contraindicated in pregnancy). Treatment is recommended in patients with acute infection, congenital Chagas, immunosuppressed patients with reactivation, and women of child-bearing age. Treatment MAY be offered in patients with indeterminate disease and those with chronic chagas cardiomyopathy

-all patients with chronic disease should get yearly EKGs