Which organ systems are affected by Chagas disease (American trypanosomiasis)?

Updated: Apr 26, 2019
  • Author: Louis V Kirchhoff, MD, MPH; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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The heart is the most commonly affected organ in persons with chronic Chagas disease. [55, 56, 57, 58] Autopsy may reveal marked bilateral ventricular enlargement, often involving the right side more than the left, in the heart of patients who die of chagasic heart failure (see image below). The ventricular walls are often thin, and mural thrombi and apical aneurysms may be present. In addition, diffuse interstitial fibrosis, widespread lymphocytic infiltration, and atrophy of myocardial cells may all be present.

Chest radiograph of a Bolivian patient with chroni Chest radiograph of a Bolivian patient with chronic Trypanosoma cruzi infection, congestive heart failure, and rhythm disturbances. Pacemaker wires can be seen in the area of the left ventricle.

T cruzi parasites are rarely found during microscopic examination of stained sections of myocardial tissue; however, in numerous studies, T cruzi ‑specific polymerase chain reaction (PCR) assays have demonstrated parasites in areas of focal inflammation. [59, 60, 61] Pathologic changes in the conduction systems of chronic chagasic hearts are also common and often correlate with dysrhythmias. [62] Chronic inflammatory lesions and dense fibrosis frequently involve the right branch and the left anterior branch of the bundle of His, but lesions may also be found in other segments of the conduction system.

Salient features on gross examination of the colon or esophagus in patients with chronic chagasic gastrointestinal disease (megadisease) include dilatation and muscular hypertrophy of the affected organs (see images below). [63, 64, 65, 66, 67, 68] Focal inflammatory lesions with lymphocytic infiltration are visible on microscopy. The number of neurons in the myenteric plexus is often markedly reduced, and periganglion and intraganglion fibrosis with accompanying Schwann cell proliferation, along with lymphocytosis, are present. In most patients with megadisease, the functional effects of this parasympathetic denervation are limited to the esophagus or colon, but clinically manifest dysfunction of the ureters, biliary tree, and other hollow viscera has been reported.

Barium swallow radiographic study of a Brazilian p Barium swallow radiographic study of a Brazilian patient with chronic Trypanosoma cruzi infection and megaesophagus. The markedly increased diameter of the esophagus and its failure to empty are typical findings in patients with megaesophagus caused by Chagas disease. Courtesy of Dr. Franklin A. Neva, Bethesda, MD.
Air-contrast barium enema of a Bolivian patient wi Air-contrast barium enema of a Bolivian patient with chronic Chagas disease and megacolon. The markedly increased diameters of the ascending, transverse, and sigmoid segments of the colon are readily apparent.

The pathogenesis of cardiac and gastrointestinal lesions of chronic Chagas disease has been a focus of debate for decades. [69, 70, 71] During the last 20 years, however, convincing evidence has shown that low levels of parasites in chronically affected tissue, detectable with molecular methods, provokes a chronic inflammatory response that eventually leads to the pathologic changes observed microscopically and organ dysfunction. [60, 72]

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