Chagas disease natural history, complications and prognosis

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

The incubation period of T. cruzi is 1-2 weeks following transmission. Nonetheless, the majority (90%-95%) of infected individuals remain asymptomatic in the acute phase following Chagas disease infection. Nonetheless, the majority remain chronically infected and demonstrate clinical symptoms only after several years/decades of infection. Approximately 1/3 of patients develop manifestations of the chronic Chagas disease, namely cardiac conduction system dysfunction, GI denervation with esophageal and/or colonic dysfunction (megaesophagus and megacolon). Chagas cardiomyopathy is the most common chronic manifestation of the disease and accounts for approximately 80-90% of chronic manifestations. The majority of patients with Chagas cardiomyopathy die within 2 years of symptom onset.

Natural History

Acute Phase

• The incubation period of T. cruzi is 1-2 weeks following transmission. Nonetheless, the majority (90%-95%) of infected individuals remain asymptomatic in the acute phase following Chagas disease infection.

• Some individuals may experience mild and non-specific clinical manifestations, such as fever, anorexia, and fatigue. These symptoms usually self-resolve within 4-8 weeks.

• Rarely, the acute phase of Chagas disease is life-threatening, and patients may present with either myocarditis of meningoencephalitis that require hospitalization.

Asymptomatic (Indeterminate) Chronic Phase

• The majority of patients are asymptomatic during the acute phase but remain chronically infected.

• Early during the chronic state, patients are asymptomatic.

Symptomatic Chronic Phase

• Several years/decades following the initial acute phase, approximately 1/3 of patients develop manifestations of the chronic Chagas disease, namely cardiac conduction system dysfunction, GI denervation with esophageal and/or colonic dysfunction (megaesophagus and megacolon).

• Chagas cardiomyopathy is the most common chronic manifestation of the disease and accounts for approximately 80-90% of chronic manifestations. It is highly arrhythmogenic and often manifests with right bundle branch block, AV block, tachyarrhythmia/bradyarrhythmia. Patients typically progress to congestive heart failure and may develop thromboembolic events due to thrombus formation (often due to either dilation of the left ventricle or aneurysm formation). The majority of patients with Chagas cardiomyopathy die within 6 months - 2 years of onset of cardiac symptoms.

• Less commonly (10-20%), patients develop GI manifestations of chronic Chagas disease. Early esophageal Chagas disease often manifests with dysphagia, odynophagia, cough, reflux, and regurgitation. As the disease progresses, individuals experience significant weight loss and aspiration. Similarly, patients with colonic Chagas disease usually complain of constipation early in the disease that often progresses to development of fecaloma, volvolus, and ischemic bowel disease.

Complications

Complications of Chagas disease include:

• Myocarditis
• Tachyarrhythmia
• Bradyarrhythmia
• AV block
• RBBB
• Apical aneurysm
• Congestive heart failure
• Meningoencephalitis
• Thromboembolism
• Sudden death
• Esophagitis
• Esophageal cancer
• Fecaloma
• Volvulus of sigmoid colon
• Ischemic bowel disease
• Aspiration pneumonia

Prognosis

• Approximately 1/3 of chronically infected patients develop clinical manifestations of chronic Chagas disease.
• Once Chagas cardiomyopathy becomes symptomatic, the prognosis is poor, and the majority of patients die within 6 months to 2 years following symptom onset.
• Patients with HIV are at an increased rate of developing complications, even during the early phase of Chagas disease. HIV-positivity is associated with increased risk of Chagas myocarditis and meningoencephalitis.
• The following Chagas disease prognosis index estimates the 10-year risk of Chagas disease-related mortality:. Based on data from approximately 500 patients, this index incorporates individual information from the clinical aspects, X-ray findings, EKG, echocardiography and Holter.

Prognosis Index

Clinical Feature	Points
NYHA class III or IV	5
Cardiomegaly	5
Wall motion abnormalities	3
Non-sustained ventricular tachycardia	3
Low voltage on ECG	2
Male gender	2

Total Points	10-year Risk of Chagas Disease-related Mortality
0–6	10%
7–11	40%
12–20	85%