Frequently Asked Questions
Consult the Network's list of frequently asked questions, with brief answers prepared by the clinical committee.
Go to FAQChagas in Nicaragua
Clinical care guide based on current protocols for the diagnosis, treatment and follow-up of Chagas disease.
Diagnosis
Summary
Acute phase
- Diagnosis in the acute phase is parasitological (Manual 111, Proc. 6).
- If the first parasitological test is negative, repeat after 15 days; if suspicion persists, serology at 2 months (Manual 111, Procs. 6.4-6.7).
Chronic phase
- Crude-antigen ELISA and confirmation with ELISAr (Manual 111, Procs. 7.2-7.4).
- If the confirmatory test is negative, a second sample after 30 days (Manual 111, Procs. 7.2-7.4).
Newborn
- Parasitological test at birth; if negative, serology at 12 months (Manual 111, Proc. 8).
Blood bank screening
- Screen 100 % of donations (Standard 110, p. 39; Manual 111, Proc. 5).
- Reactive samples are discarded and confirmed at the CNDR (Manual 111, Proc. 5).
- A positive donor cannot donate again (Standard 110, p. 39).
Source: Technical Standard and Procedures Manual for the Prevention, Control and Care of Chagas Disease (MINSA, 2013, Standards 110 and 111)
Acute phase: sample and techniques
Take 2-3 ml of blood with and without anticoagulant in people over 1 year, or 3 heparinised capillaries under 1 year; the sample is sent within 6 hours at 4-8 °C (maximum 48 hours) (Manual 111, Procs. 6.2-6.3).
- Strout in people over 1 year.
- Microhaematocrit in children under 1 year.
- Fresh drop and thick smear as alternatives; the malaria thick smear is also checked for T. cruzi.
Newborn sample collection
Take 1-3 ml of cord blood or 3 heel capillaries; the test is a microhaematocrit (or fresh drop) (Manual 111, Proc. 8).
Treatment
Summary
Who to treat
- Always treat the acute phase (Manual 111, 16.1).
- In the chronic phase, give treatment to people under 18 years (grade A) and prioritise this group (Manual 111, 16.1; Annex 9).
- Over 2 years of age, supervised outpatient care; under 2 years or immunocompromised, inpatient care (Manual 111, 16.5).
Regimens and doses
- Nifurtimox and benznidazole, orally, for 60 days (Manual 111, Proc. 16.7).
- Day 1: ¼ of the dose; days 2 and 3: ½; from day 4: the full dose (Manual 111, p. 37).
Before starting treatment
- Baseline tests: blood count with platelets, creatinine, bilirubin and transaminases, and ECG; chest X-ray only if the ECG is abnormal (Manual 111, Proc. 16.6).
- The drug is free of charge and requires informed consent (Manual 111, Proc. 13).
Contraindications and precautions
- Do not give in severe heart disease, neurological disorders, hepatic or renal failure, pregnancy, breastfeeding, megaesophagus or uncontrolled alcoholism (Manual 111, 16.2).
Source: Technical Standard and Procedures Manual for the Prevention, Control and Care of Chagas Disease (MINSA, 2013, Standards 110 and 111)
Doses by age group (Manual 111, 16.7)
Nifurtimox
- Newborns up to 2 months: 10 mg/kg/day
- Infants and children: 10-15 mg/kg/day
- Adolescents and adults: 8-10 mg/kg/day
- Severe forms (meningoencephalitis or acute myocarditis): up to 25 mg/kg/day
Benznidazole
- Newborns and infants: 10 mg/kg/day
- Children: 7-10 mg/kg/day
- Adolescents and adults: 5 mg/kg/day
Follow-up
Summary
Monitoring during treatment
- Supervise treatment at 15, 30 and 45 days (Manual 111, 16.7).
Post-treatment follow-up
- Serological follow-up at 18 months after completing treatment and then every 18 months until seronegativity (Manual 111, 21.2-21.3).
- A maximum of 4 checks in acute and congenital cases and 7 in chronic cases (Manual 111, 21.3; Standard 110, p. 43).
- Final examination: at the end of the regimen, the specialist repeats the same tests and clinical assessment as before treatment (Manual 111, Procs. 18-19).
Final outcome
- Six categories: cured and discharged, treatment failure, abandonment, transfer, and death from Chagas or with Chagas and other causes (Standard 110, pp. 18-19).
- Treatment failure is defined as the absence of seronegativity after 5 years in acute/congenital cases and 10 years in chronic cases (Standard 110, pp. 18-19).
Retreatment
- The same drug is not repeated unless acute reinfection is proven (Standard 110, p. 43; Manual 111, 21.5).
- In failure, abandonment or suspension due to severe reactions, the other trypanocidal drug is used (Standard 110, p. 43; Manual 111, 21.5).
Source: Technical Standard and Procedures Manual for the Prevention, Control and Care of Chagas Disease (MINSA, 2013, Standards 110 and 111)
Entomological surveillance of the home
It must be maintained permanently after treatment to prevent reinfection (Standard 110, p. 43; Manual 111, 17.7).
Pregnancy and Congenital Chagas
Summary
Screening in pregnancy
- Serology at the prenatal visit for pregnant women living in areas where triatomines are reported (Standard 110, p. 38; Manual 111, Proc. 3.1).
Treatment
- Contraindicated during pregnancy and breastfeeding (grade E); it is considered after the puerperium or breastfeeding (Manual 111, 16.2 and 14.3; Annex 9).
Newborn
- Every infant of a mother with confirmed Chagas disease is a suspected congenital case (Standard 110, pp. 18 and 39).
- Parasitological test at birth; if negative, serology at 12 months (Manual 111, Proc. 8).
Source: Technical Standard and Procedures Manual for the Prevention, Control and Care of Chagas Disease (MINSA, 2013, Standards 110 and 111)
Congenital infection: interpretation
A positive parasitological test confirmed by the Departmental Laboratory is a confirmed congenital case. In children 12 months or older, a positive crude-antigen ELISA and a confirmatory ELISAr are required (Manual 111, Procs. 8.5-8.8).
Pediatrics
Summary
Who to treat
- In people under 18 years with chronic infection, treatment must be given (grade A) and this group is prioritised (Manual 111, Annex 9 and 16.1).
- In children under 2 years, treatment is inpatient (Manual 111, 16.5).
Newborn
- Perform a microhaematocrit; if negative, serology at 12 months (Manual 111, Proc. 8).
Source: Technical Standard and Procedures Manual for the Prevention, Control and Care of Chagas Disease (MINSA, 2013, Standards 110 and 111)
Paediatric doses (Manual 111, 16.7)
- Nifurtimox in newborns up to 2 months: 10 mg/kg/day
- Nifurtimox in infants and children: 10-15 mg/kg/day
- Benznidazole in newborns and infants: 10 mg/kg/day
- Benznidazole in children: 7-10 mg/kg/day
Manual 111, 16.7.
Adverse Reactions
Summary
Effects by system
- General: headache, fever, oedema, lymphadenopathy, myalgia and arthralgia (Manual 111, 16.4).
- Digestive: anorexia, weight loss, nausea, vomiting, abdominal pain and diarrhoea (Manual 111, 16.4).
- Dermatological: rash between the 7th and 10th day (Manual 111, 16.4).
- Bone marrow depression: thrombocytopenia, purpura and agranulocytosis (Manual 111, 16.4).
- Neurological: peripheral polyneuritis in 20 % of adults (Manual 111, 16.4).
Pharmacovigilance
- Notify adverse reactions under MINSA Standard 63 (Manual 111, 16.4 and 17.5-17.6).
Source: Technical Standard and Procedures Manual for the Prevention, Control and Care of Chagas Disease (MINSA, 2013, Standards 110 and 111)
Management by drug
- Nifurtimox: reduce the dose or stop and treat the symptoms; restart the optimal dose after 3 days (Manual 111, 17.5).
- Nifurtimox: if symptoms reappear with general compromise, stop and refer to a specialist, who may switch to benznidazole (Manual 111, 17.5).
- Benznidazole: reduce the dose for severe nausea or vomiting by adjusting to weight (Manual 111, 17.6).
- Benznidazole: stop for peripheral neurological changes that do not improve, bone marrow depression or severe dermatitis (Manual 111, 17.6).
Surveillance
Summary
Notification
- Notify every confirmed case on the ENO form and record it in the SIVE (Manual 111, Proc. 11; Standard 110, p. 42).
Focus control
- In acute cases, within 24 hours of the first positive parasitological test (Manual 111, Proc. 12; Standard 110, p. 42).
- In chronic cases, 15 days before treatment (Manual 111, Proc. 12; Standard 110, p. 42).
- Intra- and peridomiciliary spraying (200 m radius), an educational talk and a search for triatomines and acute cases (Manual 111, Proc. 12).
Response by species
- T. dimidiata: educational visit within ≤1 month to 100 % of reporting households (Standard 110, pp. 45-46).
- R. prolixus: 1st spraying cycle ≤7 days after taxonomic confirmation (Standard 110, pp. 45-46).
- 2nd cycle at 6-12 months, in 100 % of households and a 1 km radius (Standard 110, pp. 45-46).
- Post-spraying evaluation at 3-6 months after the 2nd cycle (Standard 110, pp. 45-46).
- National Chagas Disease Day: 9 July (Standard 110, p. 48; Manual 111, Proc. 36).
Source: Technical Standard and Procedures Manual for the Prevention, Control and Care of Chagas Disease (MINSA, 2013, Standards 110 and 111)
Community entomological surveillance
It includes setting up the system, community reporting of triatomines and stratification of communities into groups A (more than 5 % of households reporting) and B (Manual 111, Procs. 23-26). Vector control is governed by Standard 213 (2024), which covers triatomines, group A spraying (100 % of households) or selective group B spraying, and a community reporting index of 0.1-4.9 %.
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