Frequently Asked Questions
Consult the Network's list of frequently asked questions, with brief answers prepared by the clinical committee.
Go to FAQChagas in El Salvador
Clinical care guide based on current protocols for the diagnosis, treatment and follow-up of Chagas disease.
Diagnosis
Summary
Who to test
- Test people with fever and exposure to Triatoma dimidiata (the “kissing bug”) in the last 5-14 days (pp. 83-84).
- Suspect after a transfusion: incubation is 30-40 days, up to 100-120 (pp. 83-84).
Acute phase
- Confirm acute cases with Strout concentration or fresh blood drop (p. 85).
- Perform direct methods from day 10 up to 60 days after primary infection (p. 101).
- Confirm seroconversion with two tests 30-90 days apart (p. 101).
Chronic phase
- Confirm with two serological tests of different principles on the same sample, at least one ELISA or IFA (pp. 102-103).
- If discordant, perform a third test or refer to a reference centre (pp. 102-103).
- Around 27 % develop cardiac damage, 6 % digestive and 3 % peripheral nervous system damage over 10-20 years (p. 87).
- Between 50 % and 70 % of infections remain without demonstrated pathology (p. 87).
Newborn
- Confirm congenital cases with Strout within the first 10 days or reactive serology from 10 months onwards (p. 85).
Source: Technical guidelines for the prevention, surveillance and control of vector-borne diseases and zoonoses (MINSAL, 2024, EA 1303)
Signs of the acute phase
Specific signs appear in 5 % of cases: inoculation chagoma (1-3 weeks) and ophthalmoganglionic complex or Romaña’s sign. Non-specific signs include fever, hepatosplenomegaly, lymphadenopathy, anaemia and oedema; severe cases may present myocarditis or meningoencephalitis (pp. 86-87).
Differential diagnosis
Acute phase: malaria, typhoid fever, infectious mononucleosis, toxoplasmosis, syphilis, rickettsiosis, brucellosis, lymphomas and visceral leishmaniasis. Chronic phase: other causes of chronic myocarditis, arrhythmias and heart failure (p. 94).
Laboratory surveillance
- Confirm every reactive donor and provide medical care (pp. 91 and 102-103).
- After a suspected transfusion, perform parasitology tests every 72 hours during the first 2 weeks and then fortnightly (pp. 91 and 102-103).
- Keep serology every 15 days until 90 days after the last transfusion (pp. 91 and 102-103).
Treatment
Summary
Who to treat
- Treat every acute and congenital case, and people under 18 years in the chronic phase (p. 95).
- Treat people over 18 years without symptoms or severe heart disease who accept informed consent (p. 95).
- For people over 50 years, assess case by case (p. 95).
- Treat reactivation due to immunosuppression and accidental exposure (p. 95).
Regimens and doses
- Give nifurtimox or benznidazole for 60 days, with the dose adjusted by age and weight (pp. 96-97).
- If intolerance prevents completing the two months, having completed at least 30 days is accepted (p. 97).
Before starting treatment
- Obtain informed consent and complete the baseline tests (pp. 95-96).
Contraindications and precautions
- Do not treat in pregnancy, pre-existing severe neurological disease or severe hepatic or renal failure (p. 98).
- During breastfeeding, assess the risk-benefit balance of nifurtimox, excreted in milk in unknown amounts (p. 98).
- Take precautions in children under 1 year with delayed height and weight gain and in drinkers with mildly elevated transaminases (p. 98).
Source: Technical guidelines for the prevention, surveillance and control of vector-borne diseases and zoonoses (MINSAL, 2024, EA 1303)
Baseline tests
- Obtain informed consent; for minors, authorisation from the parent or guardian (pp. 95-96).
- Full blood count, urinalysis, blood urea nitrogen, creatinine, serum proteins, aminotransferases and bilirubin (pp. 95-96).
- Posteroanterior chest X-ray and electrocardiogram (pp. 95-96).
Regimens and doses by group
- Nifurtimox (120 mg tablets): term newborn to 2 months, 10-20 mg/kg/day every 12 h (p. 96).
- Nifurtimox: 2 months-11 years weighing <40 kg, 15-20 mg/kg/day every 8 h (p. 96).
- Nifurtimox: 12-18 years weighing 40-60 kg, 12.5-15 mg/kg/day; >60 kg and adults >40 kg, 8-10 mg/kg/day, maximum 700 mg/day (p. 96).
- Benznidazole (100 mg tablets): up to 12 years, 5-10 mg/kg/day; adults, 5-7 mg/kg/day, maximum 400 mg/day; every 12 h (p. 97).
- Premature or low-birth-weight infants: start with 10 mg/kg once daily and increase every 48-72 h, at the specialist’s discretion (p. 96).
Measures during treatment
- Advise a low-fat, hypoallergenic diet, alcohol abstinence and avoiding sun exposure (p. 98).
- Do not drive while on nifurtimox; rule out pregnancy in women of childbearing age and advise contraception (p. 98).
Follow-up
Summary
Monitoring during treatment
- With benznidazole, perform clinical follow-up on day 7 and every 15 days until completion (p. 99).
- With nifurtimox, perform weekly follow-up during the first month and fortnightly thereafter (p. 99).
- Perform monthly follow-up at the first level with blood count and urinalysis (pp. 97-99).
- Perform two laboratory checks: before starting and between 15 and 20 days (pp. 97-99).
Serological follow-up
- Check serology at the end of treatment, at 18 and 36 months and then annually for 5 years (p. 99).
- In chronic cases, perform annual follow-up for 5 years; with cardiac pathology, specialist follow-up (p. 99).
Cure
- Consider cure by serological negativisation, with closure after two successive non-reactive tests (pp. 99-100).
- Expect negativisation in ~1 year (congenital), 3-5 years (acute), 5-10 years (recent chronic) and more than 20 years (long-standing infection) (p. 100).
Source: Technical guidelines for the prevention, surveillance and control of vector-borne diseases and zoonoses (MINSAL, 2024, EA 1303)
At each follow-up visit
- Check weight, signs, symptoms and intolerance and readjust the dose to current weight (p. 99).
- Use the minimum dose if there is intolerance (p. 99).
- Refer to a specialist for cardiac signs, electrocardiographic changes, enlarged cardiac silhouette, diabetes, cancer, hypertension, kidney disease or HIV (p. 99).
Electrocardiogram and echocardiogram
The ECG is repeated at specialist visits and whenever a rhythm abnormality appears; the echocardiogram is indicated if the cardiac silhouette changes or cardiac function deteriorates (p. 99).
Acute case and level of care
- At the end of treatment of an acute case, perform a direct test to confirm parasite clearance (p. 99).
- Manage mild, uncomplicated cases and indeterminate forms on an outpatient basis at the first level (p. 98).
- Refer severe acute heart disease, digestive haemorrhage and severe intolerance or adverse reactions to a higher level (p. 98).
Pregnancy and Congenital Chagas
Summary
Pregnancy
- Test every pregnant woman in an endemic area in the first trimester; follow up until maternal infection is confirmed or ruled out (p. 89).
- Consider the disease to have low perinatal risk, with most births at term and newborns without apparent disease (p. 88).
- The congenital route is estimated to be the most frequent source of new cases (p. 89).
- Refer a positive pregnant woman to high-risk obstetrics, with an electrocardiogram and specialist assessment (p. 89).
- Do not give trypanocidal treatment during pregnancy; maternal infection does not contraindicate breastfeeding (pp. 89 and 97).
- Start treatment after 6 months of exclusive breastfeeding or when the mother decides (pp. 89 and 97).
Newborn
- Perform Strout microconcentration, IgG, IgM and IFA at birth and before discharge, with follow-up for 1 year (pp. 89-90).
- Prefer Strout before 10 days of life (pp. 89-90).
Source: Technical guidelines for the prevention, surveillance and control of vector-borne diseases and zoonoses (MINSAL, 2024, EA 1303)
Clinical features of congenital Chagas disease
90 % are asymptomatic. Symptomatic infants present hepatomegaly, splenomegaly, jaundice, prematurity, low birth weight, anaemia and persistent tachycardia and, less frequently, neonatal hepatitis, sepsis, myocarditis, meningoencephalitis, oedema, fever or exanthema (p. 90).
Closing follow-up
- At 10-12 months, perform serology with two techniques in parallel because parasitaemia is already negative (pp. 90-91).
- Discharge the child from follow-up if the result is non-reactive (pp. 90-91).
Pediatrics
Summary
Who to treat
- Treat every person under 18 years with chronic infection, regardless of clinical manifestations (pp. 95 and 103).
- Prioritise early therapy: high response rate, reduced titres and few adverse effects (pp. 95 and 103).
- Treating girls and adolescents reduces transplacental transmission in their offspring (p. 95).
Regimens and doses
- Adjust the dose by life stage and current weight (pp. 96-97).
- Nifurtimox: from 10-20 to 15-20 mg/kg/day depending on age and 8-10 mg/kg/day (max. 700 mg) from 60 kg (pp. 96-97).
- Benznidazole: 5-10 mg/kg/day up to 12 years (pp. 96-97).
- In premature and low-birth-weight children, start with 10 mg/kg once daily and increase every 48-72 h (p. 96).
Pharmacovigilance
- Treatment during the first year of life may cause stunted weight growth, especially with nifurtimox (p. 101).
- Do not stop treatment because of stunted growth (p. 101).
- In children, adverse reactions are comparatively fewer because their frequency increases with age (p. 100).
Source: Technical guidelines for the prevention, surveillance and control of vector-borne diseases and zoonoses (MINSAL, 2024, EA 1303)
Treatment of congenital Chagas disease
- Give trypanocidal treatment if the newborn’s parasitological result is positive (p. 90).
- If negative, reassess between 10 and 12 months with specific antibody testing (p. 90).
Adverse Reactions
Summary
Common adverse effects
- They appear between 15 and 30 days of treatment; they are mild or moderate and do not require discontinuation (p. 100).
- Skin rash (more with benznidazole), nausea, vomiting, diarrhoea, epigastric pain, fever, arthralgia, myalgia, headache, insomnia and irritability (pp. 100-101).
- Transaminase elevation more than three times the upper limit of normal and eosinophilia (pp. 100-101).
Serious adverse effects
- Leucopenia below 2,500/mm³ due to neutropenia, thrombocytopenia and Stevens-Johnson syndrome with benznidazole (p. 101).
Pharmacovigilance
- Report all suspected adverse reactions, described or not, and pharmaceutical and therapeutic failures to the pharmacovigilance officer (p. 101).
Source: Technical guidelines for the prevention, surveillance and control of vector-borne diseases and zoonoses (MINSAL, 2024, EA 1303)
Management of adverse reactions
- Reduce the dose for intense nausea or vomiting (p. 97).
- Stop treatment for severe vomiting that persists after dose reduction (pp. 98-99).
- Stop treatment for peripheral neuropathy that does not improve, bone marrow depression or severe benznidazole dermatitis (pp. 98-99).
Surveillance
Summary
Notification
- Notify acute and congenital Chagas disease through VIGEPES-01 within the first 24 hours; chronic cases go to the VIGEPES repository (p. 132).
- ICD-10 coding: B57.0 and B57.1 acute; B57.2-B57.5 chronic (pp. 133-134).
Field investigation
- Investigate with a multidisciplinary team within the first 24-48 hours (24 h in 7.5.2 and 48 h in 8.4) (pp. 110 and 132).
- Close the case with the VIGEPES-01/02/03 forms (p. 132).
Entomological surveillance
- Conduct the baseline entomological survey in 100 % of the AGI (p. 103).
- Classify risk by the house infestation index: ≤5.0 % low and >5 % high (p. 105).
- For R. prolixus, spray 100 % of houses within 24 hours or less (p. 109).
Focus control
- Investigate 24 hours after detection of a suspected or confirmed acute case (p. 110).
- Inspect intra- and peridomiciliary areas and actively search household contacts (p. 110).
- Record everything in the clinical record and information systems (p. 110).
Source: Technical guidelines for the prevention, surveillance and control of vector-borne diseases and zoonoses (MINSAL, 2024, EA 1303)
Sample quality and referral
- Send 100 % of positive and 10 % of negative samples to the LNSP (p. 102).
- Also send 100 % of discordant samples between two serological tests of different principles (p. 103).
Post-spraying evaluation
- Carry out the post-spraying evaluation with the SIBASI entomologist at 7-10 days and follow up to 60 days (pp. 108-109).
- If the post-spraying index is ≥5.0 %, spray 100 % of the locality (pp. 108-109).
- If it is <5.0 %, spray only positive houses and their surroundings (pp. 108-109).
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