Treatments

Two drugs exist to treat Chagas disease: benznidazole and nifurtimox. They are both administered orally over a period of 60 to 90 days, and medical supervision is necessary as they are not exempt of adverse effects, although they are better tolerated in children.

The younger the patient and the more recent the infection, the more effective the treatment. Treatment thus is recommended in all patients with acute, congenital, or reactivated forms of Chagas disease. Reactivation can occur in immunocompromised patients (e.g. those with HIV co-infection).

In the case of chronic disease, current recommendations suggest that all patients under 60 years of age with positive serology for Trypanosoma cruzi be treated to prevent against heart and digestive complications. No valid markers for monitoring treatment response have yet been developed. Polymerase chain reaction–based detection of T. cruzi infection indicates treatment failure, but a negative result does not necessarily imply treatment success. Anti-T. cruzi antibodies in serum can take years to disappear. Patients who have received treatment must therefore undergo regular check-ups.

Systematic review on the evaluation and treatment of Chagas disease

Bern C, Montgomery SP, Herwaldt BL,Rassi A Jr,Marin-Neto JA,Dantas RO,Maguire JH,Acquatella H,Morillo C,Kirchhoff LV,Gilman RH,Reyes PA,Salvatella R,Moore AC. Evaluation and treatment of chagas disease in the United States: a systematic review. JAMA. 2007 Nov 14;298(18):2171-81.

Instructions for using antiparasitic drugs approved for the treatment of Chagas disease

BENZNIDAZOL

Indicated for the treatment of acute, chronic and reactivated forms of T. cruzi infection in adults and children.

Contraindications:

  • Absolute: severe liver failure, pregnancy, advanced forms of Chagas disease.
  • Relative: use minimum dose in cases of kidney failure (creatinine clearance <11); do not use in breastfeeding women due to a lack of evidence supporting its use during this period.

Posology: 5 mg/kg/d for 60 days, divided into 2 doses a day (8-10 mg/kg/d in children)

  • Maximum dose: 400 mg/d, elimination half-life of 12 hours.
  • Presentation: 100 mg double-scored tablets.

How to calculate the dose of benznidazole by weight per day and number of days’ treatment:

WEIGHT (in kg) x 5 x 60 = TOTAL DOSE for the patient.

TOTAL DOSE / 60 or WEIGHT (in kg) x 5 = DAILY DOSE for 60 days (maximum 400 mg).

If the daily dose exceeds 400 mg/d: TOTAL DOSE/400 = number of days’ treatment.

NIFURTIMOX

Indicated for the treatment of acute, chronic and reactivated forms of T. cruzi infection in adults and children.

Contraindications:

  • Absolute: severe liver failure (99% of nifurtimox is metabolized in the liver), pregnancy, advanced forms of Chagas disease.
  • Relative: use minimum dose in cases of kidney failure (creatinine clearance <11); do not use in breastfeeding women due to a lack of evidence supporting its use during this period.

Posology for adults: 10 mg/kg/d for 60 days, divided into 3 doses a day.

  • Recommended dose: 8-10 mg/kg/ d
  • Recommended duration of treatment: 60-90 days
  • Maximum dose: 20 mg/kg/d, elimination half-life of 2-5 hours.
  • Presentation: 120 mg double-scored tablets.

Summary of dose schedule for Nifurtimox:

Weight Total Dose Adjusted Dose/Tablets No. of Days’ Treatment
40 24000 1.00 67
45 27000 1.25 60
50 30000 1.25 67
55 33000 1.50 61
60 36000 1.50 67
65 39000 1.75 62
70 42000 1.75 67
75 45000 2.00 63
80 48000 2.00 67
85 51000 2.00 71
90 54000 2.00 75
95 57000 2.00 79
100 60000 2.00 83

Follow-up During Treatment

Clinical follow-up:

  • Benznidazole: 7 days after start of treatment and every 2 weeks thereafter until completion of treatment.
  • Nifurtimox : weekly for the first month and thereafter every 3 weeks until completion of treatment.

Blood Tests:

  • Days 7-21-35-49 and end of treatment if blood alterations were detected on day 49.
  • Recommended tests: complete blood count, white blood cell count, AST, ALT.

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