Chagas disease is a chronic parasitic infection caused by the protozoan Trypanosoma cruzi, transmitted primarily by triatomine bugs (kissing bugs) in Latin America and increasingly through congenital transmission, blood transfusion, organ transplantation, and oral routes worldwide. The Pan American Health Organization estimates that approximately 6-7 million people are infected globally, with roughly 30,000 new cases and 10,000 deaths per year, and over 75 million people at risk in 21 endemic countries from Mexico to Argentina.
Chagas disease (ICD-10: B57.0 acute Chagas disease with heart involvement; B57.1 acute without heart involvement; B57.2-B57.5 chronic with various organ involvement), also called American trypanosomiasis, is a zoonotic infection caused by the kinetoplastid protozoan Trypanosoma cruzi. The parasite cycles between mammalian reservoirs (dogs, rodents, opossums, armadillos) and bloodsucking triatomine vectors of the genera Triatoma, Rhodnius, and Panstrongylus that defecate during or after feeding, depositing T. cruzi trypomastigotes near the bite or on mucous membranes. The parasite enters through breached skin or conjunctiva, transforms into amastigotes within host cells (especially cardiac and smooth muscle), and replicates intracellularly.
The key symptoms of Chagas Disease are: Asymptomatic acute infection in 95% of cases; symptoms develop in only a minority of newly infected adults., Romana sign — painless unilateral periorbital edema with conjunctivitis and preauricular lymphadenopathy at the conjunctival site of inoculation, lasting 3-8 weeks., Chagoma — indurated erythematous swelling at the bite site, often on the face or arm, with regional lymphadenopathy., Fever, malaise, headache, myalgia, anorexia, and hepatosplenomegaly during the acute phase 4-8 weeks after exposure., Decades of asymptomatic indeterminate phase in 60-70% of chronically infected individuals, identifiable only by positive serology., Palpitations, dizziness, syncope, exertional dyspnea, ankle swelling, and exercise intolerance in chronic Chagas cardiomyopathy., Sudden cardiac death from ventricular arrhythmias, particularly in patients with left ventricular dysfunction or apical aneurysm..
Diagnosis is divided by phase. In the acute phase, microscopic detection of motile trypomastigotes in fresh blood, Giemsa-stained thick smears, or by concentration techniques (Strout method, microhematocrit) is the gold standard; sensitivity is high in the first 6-8 weeks. PCR amplification of T. cruzi DNA from blood is more sensitive in acute infection and is also positive in early congenital cases. In the chronic phase, parasitemia is intermittent and below the threshold for microscopy, so diagnosis relies on serology. Two different serological tests using different antigen preparations (ELISA, indirect immunofluorescence, indirect hemagglutination, chemiluminescence) are required for confirmation per WHO recommendations; a discordant result triggers a third test. PCR can support diagnosis in chronic infection and is used to assess parasitemia in immunocompromised patients and post-treatment. After diagnosis, every patient undergoes a baseline cardiac workup: 12-lead ECG, chest X-ray, transthoracic echocardiogram, and 24-hour Holter monitoring when available. The Brazilian Andrade classification and the BENEFIT-trial Rassi score (age, ECG findings, LV systolic function, BNP/proBNP, NYHA class) stratify cardiac risk. Gastrointestinal evaluation in symptomatic patients includes barium swallow for megaesophagus and barium enema or colonoscopy for megacolon. Pregnant women from endemic regions are screened serologically, and infants of seropositive mothers undergo PCR at birth and serology at 9-10 months. Immunocompromised patients (HIV, transplant) have surveillance PCR to detect reactivation early.
The indeterminate chronic phase carries a normal life expectancy with annual progression to determinate disease of 2-5%. Once Chagas cardiomyopathy develops, prognosis depends on LV function and arrhythmia burden: 5-year mortality is under 5% in Andrade stage I (ECG abnormality without LV dysfunction) and 50-70% in advanced stages with severe LV dysfunction and ventricular arrhythmias. The Rassi score stratifies 10-year mortality from under 10% (low risk) to over 70% (high risk). Antiparasitic treatment of acute disease produces parasitologic cure in over 90%, dramatically reducing long-term complications. Treatment of chronic indeterminate disease in young adults reduces progression to determinate disease and improves long-term outcomes in observational cohorts. The BENEFIT trial showed that benznidazole in established cardiomyopathy does not improve clinical outcomes but does reduce parasitic load. Cardiac transplantation provides good results in selected end-stage Chagas cardiomyopathy with 5-year survival of 60-70%.
Patients with positive Chagas serology should be referred to infectious disease or tropical medicine for confirmation, staging, and antiparasitic treatment decisions. Concurrent cardiology evaluation is essential because cardiac involvement determines prognosis. Gastroenterology and surgery are involved when megaesophagus or megacolon is present.
Find specialists →Antiparasitic treatment course: 60 days for benznidazole, 60-90 days for nifurtimox. Side effects typically appear in the first 2-3 weeks and may necessitate dose adjustment. Side effects largely resolve within 4-8 weeks of completion. Parasitologic response is assessed by serology over 1-3 years; persistent positive serology does not necessarily indicate treatment failure. Heart failure management is lifelong with annual review.
Cardiac rehabilitation is recommended for patients with stable heart failure and arrhythmia control, with individualized exercise prescription based on echocardiographic and rhythm findings. Patients with arrhythmias should avoid unsupervised competitive sport. Light to moderate aerobic activity (walking, swimming, stationary cycling) is safe in indeterminate disease and most NYHA class II patients.
Choose an infectious disease specialist with documented experience in Chagas disease, ideally affiliated with a center participating in WHO-PAHO Chagas networks. In non-endemic countries, multidisciplinary Chagas clinics combining tropical medicine, cardiology, and obstetrics offer the most comprehensive care.
Medically reviewed by AIHealz Medical Editorial Board · May 13, 2026
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