Frequently Asked Questions
Consult the Network's list of frequently asked questions, with brief answers prepared by the clinical committee.
Go to FAQChagas in Uruguay
Clinical care guide based on current protocols for the diagnosis, treatment and follow-up of Chagas disease.
Diagnosis
Summary
Who to test
- Confirmed case: positive parasitology or a positive serology with two different, complementary techniques, one of them IFI (2012, pág. 7; Manual 2015, pág. 50).
- Contact with a triatomine bug: serology at the consultation and repeat after 3 months if negative (2012, pág. 15; Manual 2015, pág. 50).
- A second negative serology rules out infection; a positive one requires notification and treatment (2012, pág. 15; Manual 2015, pág. 50).
- Positive serology in a blood bank: notify DEVISA and assess cardiac and digestive involvement (2012, pág. 16; Manual 2015, pág. 51).
Acute phase
- Look for the parasite or its genetic material (DNA) in blood (Manual 2015, pág. 50).
- A negative result does not rule out infection: the test is repeated serially (Manual 2015, pág. 50).
- Parasitological methods: xenodiagnosis, Strout, microhaematocrit and fresh blood drop, of low sensitivity and widely used in newborns (Manual 2015, pág. 50).
Chronic phase
- Serological techniques: ELISA, IFI, direct agglutination and indirect haemagglutination (Manual 2015, pág. 50).
- IgG at 30 days and peak at the third month; if discordant, a third technique or a higher-complexity laboratory (Manual 2015, pág. 50).
Gap left to PAHO: neither national document defines PCR, rapid immunochromatographic tests or per-technique sensitivity thresholds.
Source: MSP Uruguay — "Enfermedad de Chagas" (DLSP, September 2012) and the chapter "Enfermedad de Chagas y Chagas congénito" of the National Guide for Surveillance and Control (MSP, 2015, pp. 49-52); Decree 110/020 of 24-03-2020
Surveillance case definitions
The manual sets out the following definitions (Manual 2015, pág. 50):
- Suspected acute case: fever for more than 7 days with acute heart disease, hepatomegaly, splenomegaly or chagoma.
- Risk factors: area of vector transmission in the last 6 months, transfusion or transplant, suspected food or an infected mother.
- Suspected chronic case: a person who is asymptomatic or has cardiac symptoms and a risk factor (endemic area, positive mother, transfusion or intravenous drug use).
- Suspected transplacental case: a newborn of a mother infected with T. cruzi.
- Confirmed case: demonstrated presence of T. cruzi in acute and transplacental cases, or specific antibodies in chronic cases by two different, complementary techniques.
- Case confirmed by epidemiological link in a foodborne outbreak: a suspected case exposed to the same source as a laboratory-confirmed case.
Contact with a triatomine bug
The specimen is sent to the DLSP and serology is performed at the time of consultation. If it is positive, the person was already infected: it is notified and treatment is started. If it is negative, it is repeated after 3 months; a second negative test rules out infection from that contact and a positive one requires notification and immediate start of treatment (2012, pág. 15; Manual 2015, pág. 50).
Positive serology in a blood bank
It is notified to DEVISA and the patient is asked about their history: place of birth (their own and their mother's), type of housing during childhood and other possible routes of infection. Cardiac and digestive involvement is assessed and, if the patient is a woman, infection is sought in all her children (2012, pág. 16; Manual 2015, pág. 51).
Treatment
Summary
Who to treat
- Treated: acute phase, transplacental infection, seropositive children under 14 years and seropositive transplant recipients (2012, pág. 23; Manual 2015, pp. 51-52).
- Transfusion- or work-related accidents and reactivations in immunosuppressed patients are also treated (Manual 2015, pp. 51-52).
- Other groups are assessed by the central level (2012, pág. 23; Manual 2015, pp. 51-52).
Regimens and doses
- Benznidazole: adults 5 mg/kg/day; children 5-10 mg/kg/day in 2 doses; for 60 days (2012, pág. 24; Manual 2015, pág. 52).
- Nifurtimox: adults 8-10 mg/kg/day; children 15 mg/kg/day; for 60 days (2012, pág. 24; Manual 2015, pág. 52).
Both drugs cure close to 100 % of cases in the acute phase; effectiveness falls as more time passes since the onset of infection (Manual 2015, pág. 51).
The medication is centralized at the MSP: it is requested from the central level (2012, pág. 24; Manual 2015, pág. 52).
Contraindications and precautions
- Contraindicated in pregnancy and in renal or hepatic failure; nifurtimox also in neurological or psychiatric disorders (Manual 2015, pág. 52).
- Give under direct supervision, monitoring side effects and parasiticidal action (Manual 2015, pág. 52).
Source: MSP Uruguay — "Enfermedad de Chagas" (DLSP, September 2012) and the chapter "Enfermedad de Chagas y Chagas congénito" of the National Guide for Surveillance and Control (MSP, 2015, pp. 49-52); Decree 110/020 of 24-03-2020
Laboratory accident
This is the only situation in which treatment is started without prior verification of infection: in an accident the corresponding parasitological tests are performed and, if infection is confirmed, it is notified to DEVISA and the medication is requested from the MSP (2012, pág. 22; Manual 2015, pág. 52).
Follow-up
Summary
Care and referral
- Care for the patient with their family doctor and refer them to a specialized outpatient clinic (Tacuarembó, Montevideo) (2012, pág. 8; Manual 2015, pág. 51).
- Refer to the UMIC of the Hospital de Clínicas if there is a cardiac disorder (2012, pág. 8; Manual 2015, pág. 51).
- Assess cardiac and digestive involvement with ECG, echocardiogram and cardiac MRI, and look for megaformations of the oesophagus and colon (2012, pág. 16).
Case record
- Build the timeline with detection, confirmation, start of treatment and seronegativization or abandonment (Manual 2015, pág. 51).
Gap left to PAHO: neither national document sets a control-serology schedule, cure criteria or a treatment regimen after delivery or breastfeeding.
Source: MSP Uruguay — "Enfermedad de Chagas" (DLSP, September 2012) and the chapter "Enfermedad de Chagas y Chagas congénito" of the National Guide for Surveillance and Control (MSP, 2015, pp. 49-52); Decree 110/020 of 24-03-2020
Follow-up of household contacts
After a confirmed case, active search for cases among household contacts is carried out by serology (retrospective search in health services is not justified) and clinical follow-up is provided to positive contacts, starting antiparasitic treatment in children under 14 years and in patients at the treating physician's discretion (Manual 2015, pág. 51).
Pregnancy and Congenital Chagas
Summary
Screening in pregnancy
- Vertical transmission is the only mechanism currently in place in Uruguay (2012, pág. 10; Manual 2015, pág. 49).
- Vector transmission has been interrupted for more than 15 years and transfusion transmission has been controlled since 1985 (2012, pág. 10; Manual 2015, pág. 49).
- The risk of vertical transmission is about 3 % and it exists in any pregnancy (2012, pp. 10 and 17).
- Decree 110/020 (24-03-2020) repeals Decree 241/995; serological screening is mandatory throughout the country (Manual 2015, pág. 51; Decree 110/020).
Treatment
- The trypanocide is contraindicated during pregnancy (Manual 2015, pág. 52).
- A pregnant woman with a positive serology is monitored during gestation and the newborn is studied (Manual 2015, pp. 51-52).
Source: MSP Uruguay — "Enfermedad de Chagas" (DLSP, September 2012) and the chapter "Enfermedad de Chagas y Chagas congénito" of the National Guide for Surveillance and Control (MSP, 2015, pp. 49-52); Decree 110/020 of 24-03-2020
Algorithm for congenital Chagas disease
- Chagasic pregnant woman → newborn → parasitological diagnosis.
- If the diagnosis is positive, start aetiological treatment immediately.
- If it is negative, perform serial parasitological tests during the first 2 weeks of life (or xenodiagnosis).
- If all are negative, perform serology after 9 months; a negative serology rules out transplacental transmission (2012, pág. 18; Manual 2015, pág. 51).
Pediatrics
Summary
Who to treat
- Treat seropositive children under 14 years (2012, pág. 23; Manual 2015, pp. 51-52).
Regimens and doses
- Nifurtimox: 15 mg/kg/day for 60 days (2012, pág. 24; Manual 2015, pág. 52).
- Benznidazole: 5-10 mg/kg/day in 2 doses for 60 days (2012, pág. 24; Manual 2015, pág. 52).
Newborn
- Serial parasitological tests during the first 2 weeks (or xenodiagnosis); if negative, serology after 9 months (Manual 2015, pág. 51).
- A positive test requires starting treatment immediately (Manual 2015, pág. 51).
Susceptibility is general and in young people the disease tends to be more severe; immunosuppressed patients, particularly people with AIDS, are at risk of complications and reactivation of the parasitosis (Manual 2015, pág. 50).
Source: MSP Uruguay — "Enfermedad de Chagas" (DLSP, September 2012) and the chapter "Enfermedad de Chagas y Chagas congénito" of the National Guide for Surveillance and Control (MSP, 2015, pp. 49-52); Decree 110/020 of 24-03-2020
Treatment of the seropositive child
- Effectiveness is close to 100 % in the acute phase and decreases over time; early treatment is a priority.
- The national indication is to treat children under 14 years and assess the remaining groups with the central level.
2012, pág. 23; Manual 2015, pp. 51-52.
Adverse Reactions
Summary
Adverse effects of antiparasitic treatment appear mainly between 15 and 30 days of treatment, with greater frequency and intensity at older ages.
Profile by drug
- Benznidazole: cutaneous and neurological reactions.
- Nifurtimox: weight loss due to hyporexia and psychiatric adverse effects.
Common adverse effects
- Skin rash, digestive disorders, general symptoms (fever, arthromyalgia), headache, irritability, paresthesia, elevated transaminases and eosinophilia.
- They are generally mild or moderate; manage with symptomatic treatment.
Serious adverse effects
- Uncommon: leukopenia, neutropenia, thrombocytopenia and Stevens-Johnson syndrome.
- Treatment discontinuation due to adverse effects is infrequent, especially in children.
Duration and frequency of adverse effects
- Thirty-day regimens are associated with fewer adverse effects than 31–60-day regimens.
- With benznidazole: approximately 4.9 % vs 10.2 %, less toxicoderma and fewer interruptions.
- In children aged 12 years or younger, adverse effects are less frequent (approximately 1.8 %) than in those older than 12 years (approximately 11 %).
Source: Guidelines for the diagnosis and treatment of Chagas disease. 2nd edition. PAHO, 2026
Surveillance
Summary
Notification
- Surveillance is universal: all health facilities are obliged to notify the event (Manual 2015, pág. 50).
- Notification is individual and weekly, on a specific form and in the on line system (Manual 2015, pág. 50).
- "Chagas agudo" and "Chagas congénito": Group B of the national list, notification within 7 days (Manual 2015, pág. 50; MSP list).
What is studied
- Clinical and laboratory surveillance to confirm the acute or chronic phase; laboratory-only for special studies (Manual 2015, pág. 50).
- Serological studies are mandatory in pregnant women, newborns of positive mothers and blood banks (Manual 2015, pág. 50).
- Prevalence in blood banks is 0.3 % of the units analysed (Manual 2015, pág. 49; 2012, pág. 16).
When the vector is present
- Send the specimen to the DLSP; capturing the vector and entomological investigation are part of the investigation procedures (Manual 2015, pp. 50-51).
Source: MSP Uruguay — "Enfermedad de Chagas" (DLSP, September 2012) and the chapter "Enfermedad de Chagas y Chagas congénito" of the National Guide for Surveillance and Control (MSP, 2015, pp. 49-52); Decree 110/020 of 24-03-2020
After a confirmed case of Chagas disease
- Complete the form and enter it in the on line system within the week or send it to the Departmental Epidemiology Unit.
- Take a sample for serology and process it in the institution's laboratory.
- Identify additional cases among household contacts by serology; in a foodborne outbreak, also all those who consumed the implicated food.
- Intensified surveillance only in the event of a foodborne outbreak.
Manual 2015, pág. 51.
Foodborne outbreaks
In a foodborne transmission outbreak the suspected food must be removed immediately and all exposed people referred for laboratory and clinical follow-up. A suspected case exposed to the same source as a laboratory-confirmed case is considered confirmed by epidemiological link (Manual 2015, pp. 50-52).
Vector and reservoir control
When the presence of the vector is confirmed, control actions are carried out according to national norms: chemical control of infested houses and their surroundings, housing improvement and keeping domestic or farm animals out of the house. No control activities are carried out on sylvatic vectors or on sylvatic or domestic reservoirs (Manual 2015, pág. 52).
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