Friday, February 3, 2012

Chagas Disease (Chagasic Esophagopathy)

Chest radiograph: A wide mediastinum with normal heart size.

Contrast series: a dilated esophagus is seen in the AP projection.

CT: The esophagus is seen dilated with fluid in the lumen.

Chagas disease is found only in Latin America. It is named after Carlos Chagas, a Brazilian doctor who first described the disease in 1909. He also described the life-cycle of the parasite, identified the insects that transmit the parasite, identified small mammals that act as reservoir hosts, and suggested means to help prevent its transmission.

Usually a person experiences no immediate symptoms following infection. Ten to 20 years later, however, Chagas disease can appear and bring with it several serious heart disorders.

Chagas disease is a protozoosis caused by the flagellate protozoa Trypanosoma cruzi. The infection is usually transmitted via the feces of blood-sucking insect vectors (reduviid bugs). The infection is mostly found in small mammals (sylvatic cycle), and human disease results from the colonization of the human habitat by some vector species (domestic cycle). Vectorial transmission (via the feces of Triatominae) is responsible for 80% of human infections. The entry of metacyclic trypomastigotes via the mucosal route (oral or ocular) is easy. Direct skin penetration seems more difficult, and generally, the parasite enters via the site of the bite or the microlesions associated with scratching.

Chagas disease results in 45,000-50,000 deaths per year. Mortality is mainly due to chronic chagasic cardiomyopathy. Sudden death, usually due to ventricular fibrillation, is the principal cause of death in 60% of cases. Bradyarrhythmia, thromboembolic phenomena, and, rarely, a ruptured aneurysm, are other causes of sudden death. Congestive heart failure (25-30% of cases), cerebral or pulmonary embolism (10-15% of cases. Symptomatic acute phases mainly occur in newborns (congenital infection) or young children. Chagasic esophagopathy is observed more frequently in the second decade of life, and chronic chagasic cardiomyopathy and colopathy are generally detected later, in the third, fourth, or fifth decade of life.

Radiographic contrast study of the esophagus: Serial radiographs of the esophagus at different times after contrast ingestion allow classification of patients into 1 of 4 evolutive stages of the chagasic esophagopathy.

With stage I, the diameter of the esophagus is normal; emptying is delayed. The organ is sometimes hyperkinetic.

With stage II, the organ is dilated (megaesophagus) and displays irregular motile activity. The gastroesophageal sphincter is hypertonic.

With stage III, dilatation and retention are important, and the motile activity is clearly reduced.

With stage IV, the esophagus is clearly dilated and elongated (dolichomegaesophagus) and atonic.


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