Chagas in Spain

Acute phase

• Parasitaemia is high; in non-endemic areas it occurs only in neonates by congenital transmission, transfusion or transplant.
• Direct parasitological (microhaematocrit) and molecular (PCR) methods; also useful in reactivation.

Chronic phase

• This is the situation of most adults; parasitaemia is low and intermittent, so diagnosis is serological.
• Two serological techniques with different antigens are required (IgG anti-T. cruzi).
• At least one must be ELISA or CLIA, with high sensitivity.
• If discordant, perform a third confirmatory test or refer to a reference laboratory (Chagas Laboratory Network).

Screening in adults and pregnant women

• Perform a high-sensitivity serological test (CLIA or ELISA, sensitivity 98–100%).
• If positive, confirm with a different serological test.

Newborn

• In the infant of a positive mother, serology is not valid until 9 months of age because of maternal antibody interference.
• Use direct techniques (microhaematocrit and/or PCR) at birth and at one month of age.
• Perform serology from 9 months of age.

Target-organ assessment

• After diagnosis, assess cardiac, digestive and neurological involvement.
• 12-lead ECG (with a 30 s rhythm strip) in all patients.
• Chest X-ray and echocardiogram are recommended.
• Symptom-directed studies: Holter, barium studies, manometry and endoscopy.

Source: consensus document on prenatal screening for Chagas disease, Ministry of Health of Spain, 2024; Roca Saumell C. et al., Aten Primaria 2015.

Regimens and doses

• Two drugs: benznidazole (BNZ), first choice for better tolerance, and nifurtimox (NFX).
• In Spain they are only available as foreign medication (AEMPS procedure + WHO form); they are not part of the usual pharmacy supply.
• BNZ in adults: 5 mg/kg/day (max. 300–400 mg/day), in 2–3 doses, for 60 days.
• BNZ in children under 12 years: 5–8 mg/kg/day.
• NFX in adults: 8–10 mg/kg/day in 3–4 doses, for 60 days.
• NFX in children: 12.5–20 mg/kg/day depending on age.

Who to treat

• Clear indication to treat: acute phase, congenital infection and reactivation in immunocompromised patients.
• Also chronic infection in people under 19 years and in non-pregnant women of childbearing age.
• Individualise with shared decision-making (limited evidence): adults aged 19–50 years with indeterminate form or mild to moderate heart disease.
• Especially consider in >50 years, due to more adverse effects and lower efficacy.

Contraindications and precautions

• Do not treat: pregnancy, severe renal or hepatic failure and, in general, advanced chagasic cardiomyopathy with heart failure or megaesophagus with significant dysphagia.

Monitoring during treatment

• Clinical and laboratory monitoring (blood count, liver and kidney panel) every 2–3 weeks.
• Avoid alcohol.
• In women of childbearing age, rule out pregnancy and use contraception during treatment and for up to 5 days afterwards.

Source: consensus document on prenatal screening for Chagas disease, Ministry of Health of Spain, 2024 (RD 1015/2009 for medicines in special situations); Roca Saumell C. et al., Aten Primaria 2015.

Cure criteria

• Clearance of the parasite from blood, serological negativisation and favourable clinical course.
• In the acute and congenital phase (<1 year), cure reaches ~100%.
• In the chronic phase, the main criterion is sustained serological negativisation, which may take years.

Follow-up in the chronic adult phase

• Individualised periodic follow-up.
• In asymptomatic patients, annual or biannual clinical assessment with cardiac evaluation.

Post-treatment follow-up

• Serology and PCR at 6 months and one year, then annually or biannually.
• Treatment failure is only demonstrated by parasite detection; first rule out poor adherence.

Source: consensus document on prenatal screening for Chagas disease, Ministry of Health of Spain, 2024 (follow-up adapted from Nunes et al., AHA 2018).

Screening of pregnant women

• Mandatory screening for every pregnant woman with risk factors, at first contact with the health system.
• It is included in the SNS prenatal screening programme (2024).
• Also for 1st- or 2nd-degree relatives with risk factors.
• Target population: women from endemic areas of continental Latin America and their daughters.
• Also transplant or transfusion recipients in endemic countries and those with >1 month stays in endemic areas.

Treatment

• Do not treat during pregnancy: BNZ and NFX are contraindicated.
• Accidental exposure is not a reason to terminate the pregnancy.
• Infection does not justify a planned caesarean section.
• Breastfeeding is not contraindicated; start maternal treatment at the end of breastfeeding.

Newborn

• In the newborn of a positive mother, perform microhaematocrit and/or PCR at birth and at one month.
• If negative, serology and PCR at 9 months (and at 12 if the result is doubtful).
• If confirmed, treat: cure is close to 100% in the first year.

Vertical transmission

• Uncommon (1–12%; <5% in the chronic phase).

Source: consensus document on prenatal screening for Chagas disease, Ministry of Health of Spain, 2024; RD 1088/2005 (blood banks); regional protocols of Catalonia, Valencia and Galicia.

Who to treat

• Treat as early as possible: better tolerance, fewer adverse effects and a higher serological negativisation rate.
• Children under 14 years respond better than adults.
• Indicate treatment in every child or adolescent with chronic infection.
• Additional benefit in girls: it reduces future congenital transmission.

Diagnosis

• At >12 months, diagnosis is the same as in adults: serology with 2 techniques, at least one ELISA or CLIA.

Role of Primary Care

• Ask about the child's biographical and family origin at the first visit, including those born in Spain to a mother from an endemic area.

Source: consensus document on prenatal screening for Chagas disease, Ministry of Health of Spain, 2024; Roca Saumell C. et al., Aten Primaria 2015; González-Tomé MI. et al., Enferm Infecc Microbiol Clin 2013.

Profile by drug

• They appear mostly between 15 and 30 days, with greater frequency and intensity with age.
• Benznidazole: mainly cutaneous hypersensitivity (erythematous-pruritic rash, a frequent cause of discontinuation), mild digestive effects, cytopenias (neutropenia) and hepatic or neurological alterations.
• Nifurtimox: anorexia, nausea or vomiting, weight loss, irritability and psychiatric alterations.
• Nifurtimox: peripheral neuropathy is dose-dependent, typical of the 2nd month, and forces discontinuation.

Management

• Mild: symptomatic treatment ± temporary dose reduction; BNZ never below 5 mg/kg/day.
• Pruritus: antihistamines. Abdominal pain: gastric protectant.
• Severe (Stevens-Johnson, DRESS or eosinophilia with systemic symptoms, severe blood dyscrasias): discontinue at any age.
• Also discontinue for peripheral neuropathy, significant psychiatric alterations or progressive weight loss.

Source: consensus document on prenatal screening for Chagas disease, Ministry of Health of Spain, 2024; Roca Saumell C. et al., Aten Primaria 2015.

Early detection

• Primary Care is the ideal setting: history of epidemiological risk in every Latin American person or person with prolonged stays in endemic areas.
• Carry out opportunistic case-finding.
• Pre-pregnancy consultation: assess the risk of CD in women of childbearing age planning pregnancy and treat before gestation if appropriate.

Control of transmission routes

• Mandatory screening in blood banks (RD 1088/2005), cord blood, organ donation or transplant and pregnant women.
• Study family members of confirmed cases with shared risk factors.
• For travellers to endemic areas (Andean highlands, Bolivia): antivector measures and caution with oral transmission.

System challenges

• Reduce underdiagnosis (<10% of infected people detected in Europe).
• Standardise the programme across all autonomous communities and improve access to medication.
• Reduce loss to follow-up (<20% to maintain the validity of the programme).

Source: consensus document on prenatal screening for Chagas disease, Ministry of Health of Spain, 2024; Roca Saumell C. et al., Aten Primaria 2015.