Frequently Asked Questions
Consult the Network's list of frequently asked questions, with brief answers prepared by the clinical committee.
Go to FAQChagas in Bolivia
Clinical care guide based on current protocols for the diagnosis, treatment and follow-up of Chagas disease.
Diagnosis
Summary
Acute and congenital infection
- Confirm with direct parasitological concentration tests and/or PCR.
- Confirm any positive PCR in an asymptomatic newborn with a second PCR.
- Repeat testing around 30 days of life.
- If the result is negative, perform serological follow-up from 8 months of life.
Chronic infection
The decision lies with the local health authority, according to its operational, regulatory and epidemiological capacity.
- With a quality management system and verification of test performance: a single ELISA with sensitivity ≥96 % and specificity ≥97 %.
- Without those guarantees: two serological tests using different antigens (ELISA, IHA, IIF or CMIA).
Population studies
- Use a single ELISA or immunochromatographic test (ICT) with sensitivity ≥90 %.
Blood bank screening
- Use a single chemiluminescence, electrochemiluminescence or ELISA test with sensitivity ≥99.5 %.
- Refer reactive donors to a specialized center to determine their serological status.
Source: Guidelines for the diagnosis and treatment of Chagas disease. 2nd edition. PAHO, 2026
Serological tests for chronic infection
Two scenarios are considered for the diagnosis of chronic infection:
- With quality standards, quality management and verification of test performance: a single ELISA with high sensitivity (≥96 %) and high specificity (≥97 %).
- Without those guarantees: two serological tests with different antigens: ELISA, IHA, IIF or CMIA.
If two tests are used and results are discordant, perform a third test or refer the sample to a reference laboratory.
Rapid diagnostic tests are not recommended in standard algorithms; their use is restricted to screening or surveillance in settings with limited access.
Quantifying antibody titers at diagnosis allows assessment of the progressive reduction in the humoral response as an indicator of therapeutic efficacy.
Tests for acute and congenital infection
Recommended methods:
- Direct parasitological concentration tests: micromethod, microstrout and microhematocrit.
- PCR.
A negative result does not rule out infection: in congenital transmission, perform serological follow-up from 8 months of life; in non-congenital acute infection, seek seroconversion one month after case detection.
A positive direct parasitological test confirms acute infection. In symptomatic patients, a positive PCR also confirms it. In asymptomatic newborns, a positive PCR must be confirmed with a second PCR (about 4–6 % are false positives).
Peak parasitemia occurs around 30 days of life; repeating the test at that age improves detection.
Treatment
Summary
Treatment indications
- ✅ Adults without cardiopathy: antiparasitic treatment (strong recommendation).
- ✅ Children with chronic infection: antiparasitic treatment (strong recommendation).
- 🔴 Adults with cardiopathy: do not indicate antiparasitic treatment (strong recommendation).
- Young patients with mild cardiopathy, such as an isolated conduction disorder: consider treatment through shared decision-making.
- Immunocompromised patients: potential benefits may be greater.
- Cardiopathy: ensure comprehensive therapeutic support.
- ✅ Acute or congenital infection: antiparasitic treatment (strong recommendation).
- ✅ Women of childbearing age: antiparasitic treatment outside pregnancy to prevent vertical transmission (strong recommendation).
Available drugs
Benznidazole or nifurtimox, not other alternatives (azoles, fexinidazole) or drug combinations (strong recommendation); interchangeable depending on availability and the adverse-event profile.
Treatment duration
Benznidazole or nifurtimox for 30 days (conditional recommendation). Where adherence to 30 days is a barrier, a 15-day regimen may be considered.
Source: Guidelines for the diagnosis and treatment of Chagas disease. 2nd edition. PAHO, 2026
Benznidazole treatment regimen
Acute cases:
- ≤40 kg: 7.5–10 mg/kg/day orally.
- >40 kg: 5–7 mg/kg/day orally.
Congenital cases:
- 10 mg/kg/day orally.
Chronic infection:
- ≤40 kg: 7.5 mg/kg/day orally.
- >40 kg: 5 mg/kg/day orally.
In all cases: divided into 2 or 3 daily doses, for 30 days.
Adverse effects are predominantly cutaneous and neurological.
Nifurtimox treatment regimen
Acute and chronic cases:
- ≤40 kg: 10–15 mg/kg/day orally.
- >40 kg: 8–10 mg/kg/day orally.
Congenital cases:
- 10–15 mg/kg/day orally.
In all cases: divided into 2 or 3 daily doses, for 30 days.
Adverse effects are predominantly digestive and psychiatric (weight loss due to hyporexia).
Follow-up
Summary
Patients should be followed up regularly and persistently.
Criteria for treatment response
- Progressive reduction of serological titers and persistently negative parasitological tests or PCR define treatment response.
- Serological negativization is observed in the long term.
- Quantifying antibody titers at diagnosis makes it possible to monitor their reduction.
Special populations
- In immunocompromised patients (HIV, transplant, immunosuppressants), monitor for reactivation of the infection (mean observed rate 27.9 %).
Post-treatment follow-up
- Perform periodic clinical and serological follow-up after antiparasitic treatment.
Source: Guidelines for the diagnosis and treatment of Chagas disease. 2nd edition. PAHO, 2026
Pregnancy and Congenital Chagas
Summary
Screening
- Screen every pregnant woman at the first antenatal visit, during delivery or at the postpartum visit with IHA or another conventional test (MC p. 14).
- A single technique is sufficient, on a ~3 mL dry tube (MC p. 14); repeat testing in subsequent pregnancies of seronegative women (MC p. 17).
Treatment
- Do not treat during pregnancy: benznidazole is contraindicated because of its teratogenic risk (MC p. 18).
- Confirm serology afterwards and refer to an adult Chagas service; monitor for dermatitis, leukopenia, thrombocytopenia, peripheral neuropathy and Stevens-Johnson syndrome (MC p. 18).
Newborn
- Take a micromethod sample (capillary tube, microhaematocrit) from cord or peripheral blood.
- If negative, repeat at one month or before 6 months of age.
- Perform serology between 6 and 12 months, preferably at 8 months (MC pp. 16-17; MP p. 60; MNO p. 29).
Family study
- Extend the study to all children of a seropositive mother and provide medical care for the mother (MP p. 60; MNO p. 29).
Source: Ministry of Health and Sports of Bolivia, National Chagas Programme — Manual of Processes for the Detection, Diagnosis, Treatment and Follow-up of Chagas Disease in Children (2007); Manual of Technical and Operational Standards… Recently Chronic Chagas Disease in Children (2nd ed., 2007); Manual of Standards for the Diagnosis and Treatment of Congenital Chagas Disease (2011) and Protocol for the Management of Adverse Reactions to Aetiological Treatment (2007)
Collecting the umbilical cord sample
- Clean the distal end of the cord, open the clamp and collect the sample into a heparinised tube without filling it completely (MC p. 16).
- Mix gently ten times, label the tube and refrigerate without freezing for a maximum of 12 hours (MC p. 16).
Treatment of congenital Chagas disease (under 1 year)
- Dissolve one 100 mg benznidazole tablet in 10 mL of water (10 mg/mL) and shake before each use (MC p. 20).
- Start at 7 mg/kg/day in two doses every 12 hours and adjust to 10 mg/kg/day to complete the 30 days (MC p. 20).
- Prolong treatment by the same number of days if the interruption lasted less than 7 days, until the 30 days are completed (MC p. 20).
- Restart the 30-day regimen if the interruption exceeds 7 days.
- Store in an opaque bottle, give the first dose with the mother and supply the diluted medicine for one week (MC p. 20).
- Do not harmonise the congenital 30 days with the 60 days of children aged 9 months to under 15 years: different populations (MP p. 63).
Interpretation of newborn serology
- Interpret IHA at 6-12 months: repeat after 3 months if the titre is 1/16, 1/32 or 1/64.
- Treat as congenital Chagas disease if the titre is 1/128 or higher (MC p. 17).
Case definition and notification of congenital Chagas disease
- Define as congenital the infant of a seropositive mother with a positive micromethod before 6 months of age (MC p. 18).
- Consider it congenital if serology is positive from 6 months of age, once other transmission routes are ruled out (MC p. 18).
Resources
Pediatrics
Summary
Who to treat
- Treat children from 9 months to under 15 years in an endemic area under vector control (MP pp. 29 and 61; MNO pp. 19-20).
- Require residual vector infestation <3 % and no intradomiciliary colonisation.
Detection
- Screen with immunochromatography and confirm positives with quantitative ELISA at the second level (MP p. 61; MNO p. 20).
- Process 10 % of negatives with ELISA as internal quality control (MP p. 61).
Regimens and doses
- Benznidazole 5-7 mg/kg/day in two doses for 60 days; maximum 300 mg/day (MP pp. 63-64; MNO pp. 35 and 38; PRAM p. 43).
- Nifurtimox 10-15 mg/kg/day in two doses, 60 days, reserved for severe ADRs to benznidazole (MP pp. 63-64; MNO pp. 35 and 38; PRAM p. 43).
- Keep the national 60-day regimen; do not harmonise it with the 30 days of the PAHO 2026 Guideline (MP p. 63; MNO p. 35).
Before starting treatment
- Rule out tuberculosis, severe anaemia and renal or hepatic failure, and require signed informed consent (MP p. 62; MNO pp. 29-30).
Monitoring during treatment
- Monitor weekly and weigh at each visit to adjust the dose (MP p. 64; MNO p. 36).
- Make a home visit if the child does not attend before the 5th day (MP p. 65; MNO p. 32).
- Discharge the patient on completing the 60 days of treatment (MP p. 66; MNO p. 41).
Source: Ministry of Health and Sports of Bolivia, National Chagas Programme — Manual of Processes for the Detection, Diagnosis, Treatment and Follow-up of Chagas Disease in Children (2007); Manual of Technical and Operational Standards… Recently Chronic Chagas Disease in Children (2nd ed., 2007); Manual of Standards for the Diagnosis and Treatment of Congenital Chagas Disease (2011) and Protocol for the Management of Adverse Reactions to Aetiological Treatment (2007)
Contraindications
- Do not start treatment in the presence of any of these contraindications (PRAM p. 28; MNO p. 34):
- Inability to ensure follow-up during treatment by trained health personnel.
- Moderate to severe hepatic, renal or neurological conditions.
- Systemic infections and moderate to severe cardiac or respiratory failure.
- Acute infectious diseases.
- History of seizures or epilepsy.
- Breastfeeding and pregnancy.
- Severe malnutrition, chronic diarrhoea and severe anaemia.
- Tuberculosis.
Preparation and administration
- Scored tablets of 100 mg (benznidazole) and 120 mg (nifurtimox), divisible into halves or quarters (MP pp. 63-64; MNO pp. 36 and 40).
- Keep in an opaque bottle, protected from light and moisture, and give after meals (MP pp. 63-64; MNO pp. 36 and 40).
- Never combine missed doses: give the full daily dose from the start (MP pp. 63-64; MNO p. 35).
- Increase from 5 to 7 mg/kg/day (benznidazole) or from 10 to 15 mg/kg/day (nifurtimox) to avoid excessive fractionation (MP pp. 63-64; MNO p. 35).
- Supply the pre-divided medicine for 7 days; the first dose is given by the physician (MP p. 65; MNO p. 40).
Interruptions and referral
- When restarting suspended treatment, count the days from the suspension until the 60 effective days are completed (MNO p. 41).
- Give the medicines to the referral health centre if the child migrates or travels (MP p. 65; MNO p. 41).
Effectiveness
- Favourable outcome in more than 70 % of children under 15 years of age (MP p. 27).
- Serological negativisation in up to 60 % of schoolchildren under 12 years of age (MP p. 57).
- Effectiveness close to 100 % in children under 1 year, greater the younger the child (PRAM p. 15).
Scope of these standards
- They cover 9 months to under 15 years of age and congenital Chagas disease; adults follow the PAHO Guideline (MP p. 29; MC p. 21).
Resources
Adverse Reactions
Summary
Classification and frequency
- Classify ADRs as type A (dose-dependent, ~80 %) and type B (idiosyncratic or hypersensitivity) (PRAM p. 16).
- Report mild to severe ADRs in 69.7 % and severe ADRs (Stevens-Johnson syndrome, toxic epidermal necrolysis) in 5.3 % (PRAM, preface).
- In young children they are uncommon (20 %) and mild (PRAM p. 15).
- Classify them by severity (mild, moderate, severe) and site (dermatological, digestive, neurological, haematological) (PRAM pp. 20-21).
Management of an ADR
- Withhold the dose and consult the paediatrician or physician for any ADR (MP p. 67; PRAM p. 23).
- Restart until the scheduled days are completed and switch to nifurtimox if the ADR reappears.
- Dermatitis appears around the 9th day and polyneuropathy from the 4th week (PRAM pp. 22 and 25).
Pharmacovigilance
- Benznidazole as first choice; nifurtimox as second alternative for severe ADRs (PRAM p. 15; MP p. 63).
- Monitor weekly during the 60 days and once 15 days after treatment ends (PRAM p. 18).
- Rescue within 24 hours for a mild or moderate ADR and assess causality with the Naranjo algorithm (PRAM pp. 18-19).
Source: Ministry of Health and Sports of Bolivia, National Chagas Programme — Manual of Processes for the Detection, Diagnosis, Treatment and Follow-up of Chagas Disease in Children (2007); Manual of Technical and Operational Standards… Recently Chronic Chagas Disease in Children (2nd ed., 2007); Manual of Standards for the Diagnosis and Treatment of Congenital Chagas Disease (2011) and Protocol for the Management of Adverse Reactions to Aetiological Treatment (2007)
Dermatological management
- They are the most frequent reactions: about half of all ADRs (PRAM pp. 20 and 22).
- Mild: continue, review the dose (maximum 300 mg/day of benznidazole, every 12 hours) and give chlorpheniramine or loratadine with topical hydrocortisone (PRAM p. 23).
- Moderate: suspend for 3 to 5 days, give an antihistamine plus a corticosteroid and monitor daily (PRAM pp. 22-23).
- If the signs subside, continue at the minimum dose; if they reappear, stop benznidazole and consider nifurtimox (PRAM pp. 22-23).
- Severe: Stevens-Johnson syndrome (mortality <5 %) and toxic epidermal necrolysis (mortality 30 %).
- Stop immediately, stabilise, refer urgently to the third level and admit to a burns unit or intensive care (PRAM pp. 22-23 and 27).
Digestive and neurological management
- Severe digestive: stop and refer urgently for continuous abdominal pain, uncontrollable vomiting, weight loss >10 %, dark urine, hepatomegaly or jaundice (PRAM pp. 24-25).
- Severe neurological: stop and refer for disabling functional impairment, permanent pain or altered sensation (PRAM pp. 24-25).
- Moderate: suspend for 3 to 5 days and give aluminium hydroxide, ranitidine, domperidone, ibuprofen or paracetamol with B complex (PRAM pp. 24-25).
- Continue at the minimum dose if the reaction resolves (PRAM pp. 24-25).
Haematological management
- Stop and refer urgently to the third level for petechiae, spontaneous bruising, mucosal bleeding or fever without a focus (PRAM p. 26).
- Leukopenia, thrombocytopenia, agranulocytosis and anaemia may occur; severe bone marrow depression is very rare (MNO p. 37).
Polyneuropathy
- It is dose-dependent: with 5 mg/kg/day of benznidazole it appears in 10 to 30 % of cases (PRAM p. 43).
- It occurs from the 4th week and sometimes after treatment, with cumulative doses of 15 g (PRAM p. 43).
- B complex does not prevent it (PRAM p. 43).
- It causes paraesthesia, difficulty walking, limb pain and tingling, and usually requires permanent discontinuation of benznidazole (PRAM p. 25; MNO p. 37).
Management in congenital Chagas disease
- No severe ADRs occurred in children under 1 year: the younger the age, the lower the risk (MC p. 21).
- For a skin rash, reduce to 5 mg/kg/day and add chlorpheniramine maleate 0.2 mg/kg/day in three doses (MC pp. 21-22).
- If it persists, stop benznidazole and restart at 5 mg/kg/day; if it reappears, stop it and consider nifurtimox (MC p. 21).
- Stop immediately for petechiae, leukopenia, thrombocytopenia or skin vesicles (MC p. 21).
Educating the family
- Teach the signs that require stopping treatment and seeking care immediately: fever, rash, pruritus, vomiting, joint pain, oedema and petechiae (PRAM pp. 27 and 29).
- Record each daily dose, keep the medicine protected from light, moisture and heat, and do not self-medicate (PRAM pp. 27 and 29).
Resources
Surveillance
Summary
PAHO recommends that Member States:
- Include Chagas disease among the vertically transmitted conditions to be screened in women of childbearing age.
- Ensure the provision of benznidazole and nifurtimox and access to health services, especially for populations with disadvantaged access.
- Implement systematic case finding and training of health teams in diagnosis and treatment.
- Coordinate levels of care to ensure continuity of care.
- Strengthen information systems and epidemiological surveillance.
Implementation barriers and strategies
- Barriers: lack of knowledge of the guidelines among health personnel, shortage of diagnostic and therapeutic supplies, geographic and socioeconomic access difficulties and limited human resources.
- Strategies: training, materials, digital reminders in medical records, supportive policies, decision-support systems, audit and feedback, dissemination and administrative support.
Source: Guidelines for the diagnosis and treatment of Chagas disease. 2nd edition. PAHO, 2026
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