Frequently Asked Questions
Consult the Network's list of frequently asked questions, with brief answers prepared by the clinical committee.
Go to FAQChagas in United States
Clinical care guide based on current protocols for the diagnosis, treatment and follow-up of Chagas disease.
Diagnosis
Summary
Who to test
- Test people who lived in or traveled to Mexico, Central or South America, whose mother has Chagas, or who had a transfusion or transplant.
Acute phase
- Acute infection is diagnosed with thick and thin blood smears (microscopy) or PCR for T. cruzi DNA.
- Congenital infection is considered acute disease.
Chronic phase
- No single test is sufficiently sensitive and specific.
- Use two or more serologic tests that detect antibodies to different antigens.
Source: Centers for Disease Control and Prevention (CDC), reviewed 2024–2026. Blocks not covered by CDC are completed with the PAHO/WHO 2026 guideline (2nd ed.).
Serologic protocol
- Common techniques: ELISA and immunofluorescent antibody test (IFA).
- For discordant results, perform a third test with a different antigen or refer to a reference center.
- Quantifying the antibody titer at diagnosis helps assess treatment response (PAHO/WHO 2026 guideline).
Treatment
Summary
Who to treat
- ✅ Acute or reactivated disease: treat in all cases.
- ✅ Chronic infection in people under 18 years: treat; congenital infection counts as acute.
- ✅ Adults up to 50 years without advanced heart disease: treatment is strongly recommended.
- 🔶 Adults older than 50 years: individualize according to benefits and risks.
- 🔴 Established dilated cardiomyopathy or megaesophagus: treatment does not reverse the lesion; management is symptomatic and specialized.
Drugs and duration
- Benznidazole and nifurtimox; in adults use is off-label because FDA approves them only for pediatric patients.
- The reference duration in the United States is 60 days.
- The PAHO/WHO 2026 guideline proposes 30 days (15 if adherence is a barrier); the treating physician decides.
Contraindications
- Severe hepatic and/or renal disease.
- Pregnancy and breastfeeding: do not treat during pregnancy or while breastfeeding.
Source: Centers for Disease Control and Prevention (CDC). Clinical Care of Chagas Disease, Clinical Testing and Diagnosis and Clinical Considerations for Congenital Chagas Disease. Reviewed 2024–2026.
Adult regimens (off-label)
- Benznidazole: 5–7 mg/kg per day orally, in 2 divided doses, not exceeding 300 mg per day, for 60 days.
- Nifurtimox: 8–10 mg/kg per day orally, in 3 divided doses, for 60 days.
- The treating physician sets the dose; the FDA-approved pediatric regimens are in the Pediatrics section.
Drug access and emergencies
Where to get them: www.benznidazoletablets.com · www.lampit.com.
- Treatment questions: CDC Parasitic Diseases Inquiries, 404-718-4745, chagas@cdc.gov.
- After-hours emergencies (severe acute disease, a newborn or an immunocompromised person): CDC Emergency Operations Center, 770-488-7100.
Follow-up
Summary
Follow-up is clinical and serologic, regular and sustained.
Course of chronic disease
- About 20–30% of infected people develop clinical manifestations, mostly cardiac.
- Cardiac disease starts with right bundle branch block and/or left anterior fascicular block and may progress to dilated cardiomyopathy.
- Antiparasitic treatment does not reverse established lesions.
Response criteria
- Progressive reduction of serologic titers and negative parasitological tests or PCR.
- Serologic negativization occurs in the long term.
Special populations
- In immunocompromised people (HIV, transplant, immunosuppressants), monitor for reactivation; it requires antiparasitic treatment.
Source: Centers for Disease Control and Prevention (CDC), reviewed 2024–2026. Blocks not covered by CDC are completed with the PAHO/WHO 2026 guideline (2nd ed.).
Clinical and cardiac follow-up
- Initial and annual evaluation: medical history, physical examination and 12-lead electrocardiogram; if normal, no further testing is indicated.
- Findings suggestive of heart disease: Holter monitoring, echocardiography and exercise testing, with referral to cardiology.
- Established complications (heart failure, arrhythmias, dysphagia, constipation) require symptomatic and specialized management.
Reactivation and transplant
- Reactivation can present as an acute and potentially severe form.
- The PAHO/WHO 2026 guideline estimates a mean reactivation rate of 27.9% in immunocompromised people.
- In organ transplantation, screen donor and recipient and monitor for reactivation during immunosuppression.
Pregnancy and Congenital Chagas
Summary
About 40,000 women of childbearing age in the United States have Chagas disease; the risk of mother-to-child transmission is 1–5%, or 63–315 infected infants per year.
Screening
Risk-based: test women who lived in Mexico, Central or South America before or during pregnancy; routine screening of all pregnant women is not recommended.
Infant diagnosis
Serology is not useful in newborns: maternal antibodies persist up to 9–12 months. Diagnosis uses blood smears and/or PCR.
Treatment
Do not treat during pregnancy or breastfeeding. All congenital cases are treated: cure among infants treated in the first year of life is over 90%.
Source: Centers for Disease Control and Prevention (CDC). Clinical Care of Chagas Disease, Clinical Testing and Diagnosis and Clinical Considerations for Congenital Chagas Disease. Reviewed 2024–2026.
Screening criteria for pregnant women
- Lived in Mexico, Central or South America (endemic region).
- Residence in the southern United States with concern about triatomine exposure.
- Previous Chagas diagnosis, or transfusion or transplant in an endemic area.
- Confirm positive results at a reference laboratory (CDC Parasitic Diseases Branch).
- A negative result rules out the disease; confirmed cases are treated after delivery.
Algorithm: evaluation of pregnant women
Step 1 — Is the pregnant woman from a Chagas-endemic region?
Mexico, Central or South America
Yes
Perform T. cruzi serology at a commercial laboratory
No
Go to step 1B
Step 1B — Exposure to triatomine bugs in the United States
History of residence in U.S. areas where triatomine bugs are known to carry T. cruzi and concern for exposure to triatomines?
Yes
Perform T. cruzi serology at a commercial laboratory
No
Chagas disease is unlikely; serologic testing has a low yield
Step 2 — Serology at a commercial laboratory
T. cruzi serology (commercial laboratory)
Negative
Chagas disease excluded
Positive
Confirmatory T. cruzi serology at a reference diagnostic laboratory: CDC Parasitic Diseases Branch Laboratory
Step 3 — Confirmatory serology
Negative
Chagas disease excluded
Positive
Clinical assessment and treatment after the infant is delivered
Antiparasitic treatment is not recommended during pregnancy or breastfeeding. The infant should be evaluated with the algorithm in the Pediatrics section.
Source: Centers for Disease Control and Prevention (CDC) — Algorithm for Evaluation of Chagas Disease in Pregnant Women and Algorithm for Evaluation of Congenital Chagas Disease (infants under 3 months and 3 months and older).
Signs and diagnosis in the infant
- Most infected infants have no symptoms; without treatment, the infection lasts a lifetime.
- May present low birth weight, prematurity, low Apgar scores, hepatosplenomegaly, anemia or thrombocytopenia.
- Severe disease (meningoencephalitis, pneumonitis, anasarca or death) is uncommon.
- Evaluate infants of mothers with Chagas, infants with compatible signs, or infants of unscreened mothers.
- Detect the parasite with blood smears and/or PCR; follow-up serology is at 9–12 months.
Pediatrics
Summary
Who to treat
Treat all children under 18 years with chronic infection; congenital infection counts as acute and is always treated.
Treatment is better tolerated than in adults; cure among infants treated in the first year of life is over 90%.
Drug approvals
- Benznidazole: FDA-approved for children 2–12 years of age.
- Lampit® (nifurtimox): from birth to under 18 years, weighing at least 2.5 kg.
Follow-up of the treated infant
- Follow-up serology at 9–12 months of age; also test siblings of an infant with congenital Chagas disease.
- Regular pediatric follow-up, clinical and serologic.
Source: Centers for Disease Control and Prevention (CDC). Clinical Care of Chagas Disease, Clinical Testing and Diagnosis and Clinical Considerations for Congenital Chagas Disease. Reviewed 2024–2026.
Regimens and doses
- Benznidazole (2–12 years): 5–8 mg/kg per day, in 2 divided doses, for 60 days.
- Nifurtimox (birth to under 18 years, at least 2.5 kg): ≥41 kg, 8–10 mg/kg/day; <41 kg, 10–20 mg/kg/day; 3 doses, 60 days.
- Take tablets with food, three times daily.
- Outside the FDA-approved age ranges, use depends on the treating physician.
Algorithm: evaluation of the infant
Step 1 — Evaluation at birth (infant under 3 months)
Infant born to a mother with suspected or confirmed Chagas disease, or an infant with symptoms of congenital Chagas disease whose mother's serologic status is unknown. At birth, test cord blood (if no maternal blood contamination) or whole blood from the infant:
Microscopic examination
Blood smear with Giemsa stain (T. cruzi trypomastigotes)
Molecular testing
PCR for T. cruzi DNA
Serology
Only if the mother was not tested during pregnancy (detects maternal antibody and determines whether the infant is at risk)
Giemsa stain or PCR positive?
No
Repeat microscopic examination and PCR at 4–6 weeks of age
Yes
Evaluate the infant for treatment
Step 2 — Repeat at 4–6 weeks of age
Giemsa stain or PCR positive?
No
Serology when the infant is 9–12 months of age
Yes
Evaluate the infant for treatment
Step 3 — Serology at 9–12 months of age
Negative
Congenital Chagas disease excluded
Positive
Evaluate the infant for treatment
If the infant is first evaluated after 3 months of age: screen infant serum for T. cruzi antibody; if positive, obtain confirmatory serology at 9–12 months of age before starting treatment.
Source: Centers for Disease Control and Prevention (CDC) — Algorithm for Evaluation of Chagas Disease in Pregnant Women and Algorithm for Evaluation of Congenital Chagas Disease (infants under 3 months and 3 months and older).
Adverse Reactions
Summary
Common with both drugs and more intense with increasing age; they appear mostly between days 15 and 30 and are usually mild or moderate.
Profile by drug
- Benznidazole: allergic dermatitis, peripheral neuropathy, anorexia and weight loss, insomnia.
- Nifurtimox: anorexia and weight loss, polyneuropathy, nausea, vomiting, headache, dizziness or vertigo.
- The PAHO/WHO 2026 guideline adds rash, gastrointestinal symptoms, fever or arthromyalgia and elevated transaminases.
Serious effects
Uncommon: leukopenia, neutropenia, thrombocytopenia and Stevens-Johnson syndrome. Treatment withdrawal due to adverse effects is low, especially in children.
Source: Centers for Disease Control and Prevention (CDC), reviewed 2024–2026. Blocks not covered by CDC are completed with the PAHO/WHO 2026 guideline (2nd ed.).
Management of adverse effects
- Mild or moderate: symptomatic treatment, without stopping the antiparasitic drug.
- Leukopenia <2500/mm³, thrombocytopenia or Stevens-Johnson syndrome: stop and evaluate reintroduction or a change of drug.
- Periodic laboratory monitoring during treatment.
Surveillance
Summary
Situation in the United States
An estimated 280,000 people have Chagas disease, many without knowing it. Vector-borne transmission is exceptional: triatomines in the South rarely infest homes; the focus is transfusion, transplant and mother-to-child transmission.
Blood donor screening
- FDA-approved tests for serologic screening of donors since 2006.
- Donors positive on both the screening and the supplemental test cannot donate again and should contact their healthcare provider.
Public health strategies
PAHO recommends that Member States:
- Include Chagas disease among the vertically transmitted infections to screen for in women of childbearing age.
- Ensure the supply of benznidazole and nifurtimox and access to healthcare services.
- Implement systematic case finding and training of the health team.
- Coordinate levels of care and strengthen information and epidemiological surveillance systems.
Source: Centers for Disease Control and Prevention (CDC), reviewed 2024–2026. Blocks not covered by CDC are completed with the PAHO/WHO 2026 guideline (2nd ed.).
Confirmation in reactive donors
- A reactive donor does not have a Chagas diagnosis: confirm with serology at a reference laboratory (e.g., the CDC Parasitic Diseases Branch).
- In 2017 FDA issued guidance to re-evaluate donors with false-positive results.
- Diagnosis and treatment questions: 404-718-4745, chagas@cdc.gov.
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