What is Chagas disease?

Chagas Disease: A Comprehensive Overview

Chagas disease is a parasitic infection caused by Trypanosoma cruzi, endemic in 21 Latin American countries, with transmission primarily through the reduviid bug (vector-borne), but also occurring through vertical transmission, blood/organ donation, and rarely through oral contact. 1

Epidemiology and Transmission

• Chagas disease affects approximately 5.7 million people, primarily in Latin America, with 62.4% living in the Southern Cone region 1
• The disease has spread beyond endemic regions due to migration, with Spain having the highest number of cases in Europe (75% of European cases) 1
• In endemic areas, transmission is primarily vector-borne through the reduviid bug, while in non-endemic regions, transmission occurs through mother-to-child transmission and blood/organ donations 1
• Prevalence varies by population, with immigrants from Bolivia showing the highest rates (10-40%), and lower rates among blood donors (0.42%) and pregnant women (4%) 1

Clinical Phases and Manifestations

Acute Phase

• Typically mild illness lasting 1-2 months with low case-fatality rate 2
• Characterized by fever, malaise, edema of the face and lower extremities, generalized lymphadenopathy, and hepatosplenomegaly 2
• Severe myocarditis may develop in a small proportion of symptomatic patients 2

Indeterminate Phase

• Asymptomatic but features lifelong, low-grade parasitemia with detectable antibodies 2
• This carrier state can be a major source of transfusion-associated transmission 2
• Many people have subtle signs of cardiac or gastrointestinal involvement before becoming symptomatic 2

Chronic Phase

• Develops in approximately 30-40% of infected individuals, 10-30 years after initial infection 1, 2
• Cardiac involvement is the most common and serious manifestation, affecting 19% of infected individuals 1, 2
• Gastrointestinal abnormalities occur in approximately 5% of infected individuals 1
• Severe cardiac events occur in about 1% of infected individuals 1

Cardiac Manifestations

• Biventricular enlargement, thinning of ventricular walls, apical aneurysms, and mural thrombi 2
• Conduction system abnormalities: right bundle-branch block, left anterior fascicular block, or complete atrioventricular block 1, 2
• Cardiac arrhythmias, including atrial fibrillation and complex ventricular ectopy 2
• Heart failure with poor prognosis (50% mortality within 4 years) 2, 3

Diagnosis

• In endemic areas, diagnosis can be made by direct parasite identification 1
• In non-endemic areas, diagnosis relies on serological tests including indirect hemagglutination assay (IHA), immunofluorescence antibody assay (IFA), and enzyme-linked immunosorbent assay (ELISA) 1, 4
• Conventional serologic tests detect antibodies against T. cruzi parasites, while nonconventional assays like F29-ELISA and AT-chemiluminescence-ELISA detect anti-T. cruzi IgG antibodies against specific recombinant antigens 4

Treatment

• Antiparasitic treatment with benznidazole or nifurtimox is most effective during the acute phase 1, 3
• Treatment efficacy diminishes in the chronic phase, particularly with advanced cardiac involvement 3
• In clinical trials, benznidazole treatment resulted in significantly higher percentages of seronegative patients compared to placebo 4
• Among patients treated with nifurtimox, 81% initiated trypanocidal therapy and 78% completed treatment, with 47% experiencing treatment-related adverse effects 1, 3
• Treatment is particularly important in immunocompromised patients due to risk of disease reactivation 3

Prognosis and Complications

• Poor prognosis is associated with complete heart block, atrial fibrillation, left bundle branch block, and complex ventricular ectopy 2, 3
• Cardiac involvement leads to a mortality rate of approximately 50% within 4 years 2, 3
• Chagas disease continues to be the leading cause of cardiomyopathy in Latin America 1

Special Considerations

• Screening is recommended for persons from endemic areas and children of mothers from these areas 1
• In athletes with Chagas disease, sports competition can be unrestricted if no objective signs or symptoms of cardiac involvement are evident 1
• With evidence of cardiac involvement, all intense competitive sports activity is contraindicated 1
• Monitoring for adverse effects during treatment is essential, as 47% of patients experience treatment-related side effects 3