Frequently Asked Questions
Consult the Network's list of frequently asked questions, with brief answers prepared by the clinical committee.
Go to FAQChagas in Panama
Clinical care guide based on current protocols for the diagnosis, treatment and follow-up of Chagas disease.
Diagnosis
Summary
Who to test
- Clinical: fever for more than 5 days, with or without myalgia, arthralgia, asthenia, diarrhoea, abdominal or chest pain, palpitations or oedema (p. 21).
- Clinical: exanthema, lymphadenopathy, hepatosplenomegaly, acute heart disease, jaundice or Romaña sign; in children the signs are harder to recognise (p. 21).
- Epidemiology: living in or visiting an area with triatomines, recent transfusion or transplant, contaminated food, an infected mother or occupational risk (p. 21).
Acute phase
- Parasitology: direct examination of peripheral blood for T. cruzi confirms the infection (p. 21).
- Serology: positive IgM with compatible clinical and epidemiological findings, or IgG with rise of ≥3 titres or seroconversion in samples ≥21 days apart (p. 21).
- Confirmed case: direct parasitaemia or two serological tests of different principles (ELISA, IFA, IHA, Western blot); if discordant, PCR or other molecular test (p. 22).
Chronic phase
- Confirmation: anti-T. cruzi IgG by at least two techniques based on different principles, preferably with titration (1st ed., p. 31).
- A negative ELISA with high clinical-epidemiological suspicion does not rule it out: a second test is required (1st ed., p. 31).
- Clinical: cardiomyopathy, conduction lesions, cardiac arrest or sudden death and congestive heart failure; megaesophagus and megacolon are uncommon in Panama (p. 22).
Newborn
- Congenital case: direct parasitaemia or PCR, or two serological tests with different principles, in a child under 1 year of a seropositive mother (p. 22).
Source: Guide for the Comprehensive Management of Chagas Disease in the Republic of Panama, 2nd edition (MINSA/CSS/PAHO-WHO, 2024; Resolution No. 0971 of 20-05-2024)
Laboratory algorithm and quality control
Screening is done at the local or regional level and all positive results are confirmed at the Central Public Health Reference Laboratory (LCRSP) of the ICGES; if results disagree, a new sample is taken. 5 % of negative results are sent to the LCRSP for quality control (1st ed., p. 32; 2nd ed., p. 41).
PCR
It is indicated in the acute phase with negative direct methods, in congenital Chagas disease with compatible symptoms and a seropositive mother (it can define the case before 6 months of age), in immunosuppressed patients and in post-treatment follow-up. In Panama it showed low sensitivity in the chronic phase, so it does not replace serology in that setting (1st ed., p. 33; 2nd ed., pp. 39-40).
Treatment
Summary
Who to treat
Indications based on the PAHO/WHO 2018 recommendations (p. 44):
- Children with chronic infection and girls or women of childbearing age with chronic infection (strong recommendation) (p. 44).
- Acute or congenital infection (strong recommendation) (p. 44).
- Adults with chronic infection without specific organ damage (conditional in favour) (p. 44).
- Adults with chronic infection and specific organ damage (conditional, moderate certainty) (p. 44).
Regimens and doses
- Two oral trypanocidal drugs: benznidazole (first choice) and nifurtimox (second choice, reserved for resistant strains or when benznidazole is unavailable) (pp. 45-48).
- The standard regimen lasts 60 days (pp. 45-48).
Where to treat
- Mild cases and indeterminate forms: outpatient management in primary care by a general physician familiar with the drug and the disease (p. 44).
- Severe acute heart disease, gastrointestinal bleeding and intolerance or adverse reactions are referred (p. 44).
- Contact with the patient should be at least weekly during the first month and then monthly or as clinically indicated (p. 44).
Before starting treatment
- Baseline tests: blood count with platelets, urea and creatinine, transaminases, bilirubin, LDH, alkaline phosphatase and general urine examination (p. 45).
- Baseline tests: chest X-ray and electrocardiogram (p. 45).
Contraindications and precautions
- Both drugs: hypersensitivity, pregnancy, severe neurological, liver or kidney disorders and severe conditions associated with the disease (p. 46).
- Nifurtimox, in addition: glucose-6-phosphate dehydrogenase deficiency (p. 48).
- Precautions: strict supervision in kidney, liver or blood disorders and monitoring of the blood count, mainly leukocytes (p. 46).
- With benznidazole: avoid alcohol because of the disulfiram-like effect and use effective contraception in women of childbearing age (p. 46).
- With nifurtimox: aluminium hydroxide to reduce gastrointestinal irritation and dose reduction if there is weight loss (p. 48).
Access
- Neither drug is registered in Panama (p. 53).
- They are purchased through the PAHO Strategic Fund and the Directorate of Pharmacies and Drugs authorises their use as an exception (p. 44).
- They are for exclusive use by MINSA: they are not sold in private pharmacies (p. 44).
- If therapy fails with one drug, the other may be tried, after reviewing the literature on cross-resistance (p. 53).
Source: Guide for the Comprehensive Management of Chagas Disease in the Republic of Panama, 2nd edition (MINSA/CSS/PAHO-WHO, 2024; Resolution No. 0971 of 20-05-2024)
Doses by group
- Benznidazole: newborns 10 mg/kg/day every 12 h, 60 days, with half the dose initially and full dose at 72 h if tolerated (p. 45).
- Benznidazole: up to 12 years 5-10 mg/kg/day in 2 doses; over 12 years and adults 5-7 mg/kg/day in 2 doses, also with HIV (p. 45).
- Benznidazole: the maximum dose is 300 mg/day (p. 45).
- Nifurtimox: 120 mg tablets, 3 times a day for 60 days, maximum 700 mg/24 h (p. 48).
- Nifurtimox: newborns 10-15 mg/kg/day every 12 h and up to 12 years 10-15 mg/kg/day every 8 h (p. 48).
- Nifurtimox: over 12 years and adults 8-10 mg/kg/day every 8 h; in HIV, 8-10 mg/kg/day in 3 doses for 90 days (p. 48).
Weight adjustment (>60 kg)
Above 60 kg the total dose must be calculated and treatment extended beyond 60 days so as not to exceed 300 mg/day. Example from the guide: 70 kg at 5 mg/kg/day would need 350 mg/day, so a rule of three is applied (300 mg × 60 days = 18,000 mg; 350 mg × 60 days = 21,000 mg) and treatment is extended to complete 70 days (p. 45).
Follow-up
Summary
Monitoring during treatment
- Complete blood count once a week (every 15 days in hard-to-reach areas) to monitor leukopenia and thrombocytopenia (p. 49).
- Transaminases, bilirubin, LDH, alkaline phosphatase, creatinine and urea nitrogen every 15 days (p. 49).
- At each visit: check weight, signs, symptoms and intolerance, and adjust the dose to the current weight (p. 49).
- The presumptive diagnosis must be confirmed or ruled out within 15 days (p. 49).
Serological follow-up
- Serology at the end of treatment, every 6 months during the first year and then annually for up to 5 years (p. 49).
- Follow-up is closed with two consecutive non-reactive tests (p. 49).
Cure criterion
- Cure means serological negativisation; there are no exact clinical criteria (p. 49).
- Expected negativisation: about 1 year in congenital infection and 3-5 years in treated acute cases (p. 49).
- Expected negativisation: 5-10 years in recent chronic cases and more than 20 years in long-standing infections (p. 49).
- In the chronic phase a progressive fall in titres is expected as a sign of future negativisation (p. 49).
Cardiac assessment
- Electrocardiogram if the patient has cardiac symptoms; if abnormal, the patient is referred to a specialist (p. 49).
Source: Guide for the Comprehensive Management of Chagas Disease in the Republic of Panama, 2nd edition (MINSA/CSS/PAHO-WHO, 2024; Resolution No. 0971 of 20-05-2024)
Treatment suspension
Treatment must be suspended for drug intolerance when the following occur (p. 49):
- Severe nausea and vomiting after reducing the dose.
- Peripheral nerve disorder that does not improve when the dose is reduced.
- Bone marrow depression.
- Severe dermatitis.
Pregnancy and Congenital Chagas
Summary
Screening during pregnancy
- Indication: serology for every pregnant woman from an endemic area, together with first-trimester screening (p. 27).
- Indication: also for any woman of childbearing age from an endemic area or with a history of having lived in one (p. 27).
- Repeat: previous negative result with a stay of more than 1 month in an area with vector presence (p. 27).
- Repeat: previous positive serology in a new pregnancy, even if the patient has received treatment (p. 27).
- Record: the result, positive or negative, is recorded in the prenatal card (p. 27).
Management of the seropositive pregnant woman
- Conduct: assess the disease stage, perform an electrocardiogram, maintain prenatal care, perform a fetal ultrasound and refer to an obstetric risk unit (p. 27).
- Treatment: benznidazole and nifurtimox are contraindicated in pregnancy (p. 27).
Breastfeeding
- Treatment during breastfeeding: allowed, because the amount passing into human milk is lower than the dose that would be given to a newborn (p. 27).
- Breastfeeding: there is no risk of transmitting the parasite through breast milk; it should be recommended and supported without restrictions (p. 28).
Newborn
- IgG curve: at 1 month titres equal the mother’s and at 2 months they fall by 2-3 titres (p. 28).
- Most children are seronegative by 6 months and a final test is done at 9 months (p. 28).
- If positivity persists from 9 months onwards, it is a congenital Chagas case and must be treated (p. 28).
Source: Guide for the Comprehensive Management of Chagas Disease in the Republic of Panama, 2nd edition (MINSA/CSS/PAHO-WHO, 2024; Resolution No. 0971 of 20-05-2024)
Manifestations of congenital Chagas disease
The newborn may present fever, hepatosplenomegaly, heart problems, anaemia or jaundice, prematurity, low birth weight, myocarditis or meningoencephalitis, or be asymptomatic; absence of symptoms at birth does not rule out infection (p. 28).
Pediatrics
Summary
Who to treat
- Children with chronic infection are treated regardless of the clinical form (strong PAHO/WHO 2018 recommendation adopted by the guide) (p. 44).
Newborn
- Early treatment of the infected newborn: benznidazole or nifurtimox for 60 days, under medical supervision (p. 28).
- Cure is confirmed by serology at the end of treatment and at one year (p. 28).
Prognosis
- Acute infection has a worse prognosis in children under 2 (p. 23).
Source: Guide for the Comprehensive Management of Chagas Disease in the Republic of Panama, 2nd edition (MINSA/CSS/PAHO-WHO, 2024; Resolution No. 0971 of 20-05-2024)
Paediatric doses by age
- Benznidazole: newborns 10 mg/kg/day every 12 h, with half the dose initially and the full dose at 72 h if tolerated (p. 45).
- Benznidazole: up to 12 years 5-10 mg/kg/day in 2 doses; over 12 years 5-7 mg/kg/day (p. 45).
- Nifurtimox: newborns 10-15 mg/kg/day every 12 h and up to 12 years 10-15 mg/kg/day every 8 h (p. 48).
- Both regimens last 60 days (pp. 45 and 48).
Adverse Reactions
Summary
Frequency and presentation
- Intolerance is uncommon in children and in the acute phase and more frequent in adults in the chronic phase (p. 46).
- The most common reactions are skin reactions and neuropathy (p. 46).
- Gastrointestinal disorders (nausea, vomiting, anorexia, diarrhoea) in about 10 % of cases; they require symptomatic clinical treatment (p. 46).
Serious reactions
- Peripheral neuropathy in <1 %, from the 5th week: interrupt until symptoms improve (p. 46).
- With high doses paraesthesia or even irreversible damage may remain; it does not improve by switching to nifurtimox (p. 46).
- Dermatitis between the 5th and 10th day: mild (<20 %) continue; moderate (<5 %) temporary interruption with antihistamines or corticosteroids (p. 47).
- Marked dermatitis (<1 %): interrupt and hospitalise (p. 47).
- Nifurtimox causes fewer skin effects (p. 47).
- Bone marrow hypoplasia (<1 %) between day 20 and 30, with thrombocytopenia <50,000 platelets/mm³: stop without readministration and transfer (p. 47).
- Monitor for leukopenia, granulocytopenia, neutropenia and agranulocytosis (p. 47).
- Ageusia (loss of taste): interrupt treatment (p. 47).
- Sore throat and fever: advise the patient to suspend temporarily and seek care immediately (p. 47).
Pharmacovigilance
- Reporting suspected adverse reactions and therapeutic failures is mandatory (Article 60 of Law No. 1 of 10 January 2001) (p. 50).
- It is done using the forms of the MINSA Pharmacovigilance Section or through the regional Noti-FACEDRA portal (www.notificacentroamerica.net); patients can also report directly (p. 50).
Source: Guide for the Comprehensive Management of Chagas Disease in the Republic of Panama, 2nd edition (MINSA/CSS/PAHO-WHO, 2024; Resolution No. 0971 of 20-05-2024)
Surveillance
Summary
Notification
- Notification is mandatory and individual, using the notification and investigation form, with local → regional → central flow and feedback to those responsible (pp. 54-55).
- Laboratories report reactive and non-reactive results monthly (pp. 54-55).
Donor screening
- ELISA screening of all blood, organ and blood product donations is mandatory since 1999 (1st ed., pp. 30 and 80-81; Resolution No. 49 of 23-06-1999).
- Reactive units are discarded, confirmed at the LCRSP-ICGES and reported to Epidemiology (2nd ed., pp. 33-34 and 54).
Serological surveys
- In at-risk areas, surveys in preschoolers and schoolchildren every 3-5 years, with samples sent to the Regional Laboratory, LCRSP or ICGES (p. 55).
Source: Guide for the Comprehensive Management of Chagas Disease in the Republic of Panama, 2nd edition (MINSA/CSS/PAHO-WHO, 2024; Resolution No. 0971 of 20-05-2024)
Entomological surveillance and vector control
Vector control and entomological surveillance are part of the national programme; the main vector is Rhodnius pallescens, with domestic behaviour, and Triatoma dimidiata, Panstrongylus geniculatus, Eratyrus cuspidatus and Triatoma dispar have also been identified (1st ed., pp. 16-18; 2nd ed., pp. 13-17 and 62-72).
Didn't find what you were looking for?
Consult your case directly with the Network's medical committee.
Member access
A more complex case? Consult your case directly with the medical committee of the Atendiendo Chagas Network.
Ask the expert · Free registration