Frequently Asked Questions
Consult the Network's list of frequently asked questions, with brief answers prepared by the clinical committee.
Go to FAQChagas in Venezuela
Clinical care guide based on current protocols for the diagnosis, treatment and follow-up of Chagas disease.
Diagnosis
Summary
Acute phase
- Direct parasitology: fresh blood (motility) and a Giemsa-stained smear (morphology); thick films are not recommended because of defibrination (pp. 20 and 24).
- Take the sample while the patient is febrile or within 12–24 h and repeat it on 3 consecutive days or more if negative (p. 24).
Chronic phase
- Serology: 2–3 tests based on different principles (ELISA, IHA, IFA, direct agglutination); two reactive results confirm (pp. 20 and 25).
- Discrepancy: a third test based on a different principle and referral to the reference laboratory (pp. 20 and 25).
- Parasitology: 100 % specificity and low sensitivity in the chronic phase; serology: 98–99 % sensitivity and 92–95 % specificity (p. 20).
Blood and organ donors
- Screening with a high-sensitivity ELISA and a whole-molecule IgG capture conjugate (p. 26).
- Two negative results release the blood or organ; a doubtful result requires discarding and confirming at a reference laboratory (p. 26).
- Two positive tests also require evaluating the patient (p. 26).
PCR
- PCR is not routine; it is recommended for congenital Chagas disease and to assess treatment failure (pp. 23 and 34).
Source: Guide for the Diagnosis, Care and Clinical Management of Chagas Disease in Venezuela (MPPS, Official Gazette No. 40.335, January 2014)
Cardiac involvement in the acute phase
In the acute phase a standard 12-lead ECG with a long recording of lead II is recommended and, if available, Holter monitoring. Fever, generalised oedema and palpitations are the triad that requires ruling out cardiac involvement (p. 37).
Treatment
Summary
Who to treat
- Indications A–E (p. 32): acute phase, congenital infection, accidental contamination, reactivation due to immunosuppression and children under 18 with positive serology.
- In chronic adults over 18 without heart disease routine treatment is not recommended (pp. 42 and 44).
- Divergence from PAHO 2026, which does recommend it: no clear benefit and frequent adverse effects; it remains for the medical committee.
Regimens and doses
- Benznidazole: 5–10 mg/kg/day in 2 doses after meals, 60 days; children close to 10 and adults 5 mg/kg/day, maximum 300 mg/day (p. 32).
- A total dose above 18 g is associated with polyneuritis (p. 32).
- Start with half the dose and increase until the fourth day (pp. 32–33).
- Nifurtimox (alternative): children 10 mg/kg/day and adults 5–8 mg/kg/day in 2–3 doses every 8–12 h, 60 days; 120 mg tablets (pp. 32–33).
Before starting treatment
- Blood count with platelets, creatinine, urea or BUN and transaminases before starting, at 3 weeks and at the end (p. 32).
- Weekly outpatient monitoring and absolute abstinence from alcohol during treatment (pp. 32 and 37).
Contraindications and precautions
- Contraindicated: pregnancy, breastfeeding, women of childbearing age who could become pregnant, chronic alcoholism and severe liver, kidney or blood disorders (p. 34).
Source: Guide for the Diagnosis, Care and Clinical Management of Chagas Disease in Venezuela (MPPS, Official Gazette No. 40.335, January 2014)
Treatment regimen (Table 3)
- Acute Chagas disease: benznidazole 5–10 mg/kg/day in 2 doses (infants and children close to 10 mg/kg/day; adults 5 mg/kg/day) for 60 days.
- Congenital transmission: benznidazole 10 mg/kg/day in 2 doses for 60 days.
- Accidental infection: benznidazole 7–10 mg/kg/day for 10 days, extendable to 30 if the parasite load is high (p. 33).
- Low-risk accident: no treatment; serological monitoring only (p. 33).
- Reactivation: same as the conventional regimen, 60–90 days.
- Nifurtimox: children 10 mg/kg/day and adults 5–8 mg/kg/day in 2–3 doses for 60 days (p. 33).
Access to the medicines
Neither drug is registered with the National Institute of Hygiene: they are supplied as a “service medicine” (p. 30).
Follow-up
Summary
Serological follow-up
- Follow-up: 2–3 tests every 6 months or at least annually, compared with the initial sample or the one at the end of treatment (p. 34).
- With effective treatment titres fall during the first year; negativisation in less than 5 years (acute) and after about 10 years (incipient chronic) (p. 34).
- A fall in titres does not define cure: full negativisation is required; the guide calls for “simple and practical” procedures (pp. 34–35).
- Parasitology and molecular biology are not routine; a negative result does not guarantee cure and the presence of T. cruzi confirms failure (p. 34).
Source: Guide for the Diagnosis, Care and Clinical Management of Chagas Disease in Venezuela (MPPS, Official Gazette No. 40.335, January 2014)
Follow-up by stage of heart disease
- Stage A (normal ECG, asymptomatic): annual medical check-up with a new ECG; risk of developing heart damage of 10–30 % (pp. 41–42).
- Stage B (heart damage without heart failure): care at levels II or III and check-ups every 6 months or sooner as clinically indicated (p. 44).
- Stage C (congestive heart disease): check-ups every two weeks or monthly and then as the treating physician decides (p. 46).
- Stage D (refractory congestive heart disease): management in highly specialised hospitals (level III); survival below 20 % at one year (p. 47).
Pregnancy and Congenital Chagas
Summary
Screening in pregnancy
- Serology at the first prenatal visit or at delivery; if positive, confirm at a reference laboratory and assess at the CEEAPCh (p. 17).
Newborn
- Cord or peripheral blood for direct parasitology (fresh or Giemsa) and serology; if resources allow, blood culture, microhaematocrit and PCR (p. 17).
- Maternal antibodies interfere with serology: IgM at birth and IgG through the year; they disappear between 9 and 12 months (pp. 17 and 27).
- Negative newborn: repeat serology at 9 and 12 months (p. 17).
- Positive newborn with criteria for the acute phase: treat immediately with benznidazole 10 mg/kg/day for 60 days (pp. 17 and 33).
- Treatment is not given during pregnancy or breastfeeding (p. 34).
Source: Guide for the Diagnosis, Care and Clinical Management of Chagas Disease in Venezuela (MPPS, Official Gazette No. 40.335, January 2014)
Congenital transmission: suspicion and confirmation
Suspected case: any newborn of a mother with a positive parasitological or serological test for T. cruzi. Confirmed case: that newborn with a positive parasitological test or with persistent positive serology once maternal antibodies are ruled out (p. 14).
Parasitological tests confirm the diagnosis when positive; serology alone may be a false positive due to maternal antibodies (pp. 27–28).
Pediatrics
Summary
Who to treat
- Children under 18 with positive serology (“incipient chronic phase”): treat even if asymptomatic (pp. 32 and 42).
- The document uses “under 19 years” when describing the paediatric evidence; this profile adopts the cut-off of 18 (pp. 32 and 42).
Severe forms
- Acute mortality is concentrated in children under 2; early treatment prevents organ involvement (pp. 12 and 38).
Regimens and doses
- Benznidazole 5–10 mg/kg/day, 60 days; in infants and children close to 10 mg/kg/day, with 100 mg tablets and a 12.5 mg dispersible one (pp. 31–32).
Source: Guide for the Diagnosis, Care and Clinical Management of Chagas Disease in Venezuela (MPPS, Official Gazette No. 40.335, January 2014)
Acute-phase syndromes
The acute phase can present with general infection, myocarditis with or without pericarditis, and meningoencephalitis; meningoencephalitis and myocarditis with congestive heart failure have a poor prognosis even with parasiticidal treatment (pp. 37–38).
Adverse Reactions
Summary
Most frequent reactions
- Skin lesions due to hypersensitivity are the most frequent reaction (p. 37).
- Toxic doses are close to therapeutic doses and reactions are more frequent in adults (p. 37).
- Table 2: digestive (weight loss, nausea, vomiting), haematological (leukopenia, thrombocytopenia, agranulocytosis), dermatological (erythema, photosensitive rash, atopic dermatitis, occasional Stevens-Johnson) and dose-dependent polyneuropathies (p. 31).
Management by severity
- Mild: treatment is not suspended; moderate: at the physician’s discretion; severe with fever and adenopathy: suspend immediately (pp. 37–38).
- Lesions: local corticosteroids and moisturising lotions; antihistamines in mild or moderate cases and occasional prednisone 20 mg/day; severe: IV steroids and hospitalisation (pp. 37–38).
- Peripheral neuropathy with pain and paraesthesia: suspend and start oral steroids and analgesics (p. 38).
- Bone marrow depression, which is uncommon, also requires suspension (p. 38).
Source: Guide for the Diagnosis, Care and Clinical Management of Chagas Disease in Venezuela (MPPS, Official Gazette No. 40.335, January 2014)
Signs of intolerance and warning signs
The most frequent signs of intolerance are (p. 37):
- Skin rash of various types.
- Peripheral or central neurotoxic phenomena: anorexia, irritability, persistent crying in infants and insomnia.
- Also tremors, loss of balance or memory, seizures, myalgia, sensory changes and paraesthesia.
- Fever.
Symptomatic management of acute Chagas disease
Signs of general infection may require antipyretics, antiemetics, antidiarrhoeals and hydration. Myocarditis is managed like myocarditis of other causes and, if it progresses to congestive heart failure, with rest, salt and fluid restriction and conventional treatment. Meningoencephalitis with seizures is treated with benzodiazepines and/or barbiturates (p. 38).
Surveillance
Summary
Notification
- Once the diagnosis is confirmed, notification to the health authorities is mandatory and opens aetiological treatment and control measures (p. 30).
- Mandatory weekly reporting of suspected and confirmed cases by the entire care network to state environmental health services and regional epidemiology (p. 18).
- Also reported weekly: diagnostic tests (positive or not), treatments to children under 18, cardiology admissions and check-ups, and maternal and child health samples (pp. 18–19).
Vector control
- Vector control and entomological surveillance are components of the PPCECh together with diagnosis, care and treatment (pp. 17–18).
Source: Guide for the Diagnosis, Care and Clinical Management of Chagas Disease in Venezuela (MPPS, Official Gazette No. 40.335, January 2014)
Notification form
The official MPPS list does not include a Chagas-specific notification form (p. 30).
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