Chagas Disease - American Trypanosomiasis - Diagnosis and Management Summary
Chagas disease (American trypanosomiasis) is an infectious disease caused by the protozoan parasite Trypanosoma cruzi (T. cruzi), which is typically transmitted by triatomine bugs of the Reduviid family
Route of infections:
1. Vector-borne (most common)
2. Vertical (22%)
3. Oral (food/drinks infected with triatomine bugs or their feces)
4. Blood (platelets transfusions)
5. Organ transplantation
6. Laboratory accidents
Triatomine bug exposure → 1-2 weeks incubation
Acute phase → 8-12 weeks
1. Most patients asymptomatic or mild (malaise, fever, hepatosplenomegaly)
2. Cutaneous manifestations:
Chagoma: inflammatory edema at the bite site (face)
Romana's sign: painless unilateral eyelid edema
3. <1% Myocarditis, meningoencephalitis
Chronic phase → (lasts indefinitely in the absence of treatment)
Indeterminate form (No signs/symptoms, positive serology, smear negative, PCR + 20-90%, normal ECG)
→ 70-80% have no disease progression: Indeterminate form persists throughout life
→ 20-30% have disease progression (10-20 years):
Determinate forms:
1) Cardiomyopathy: Conduction disorders (RBBB; others: AV blocks, PVC, tachy-/bradyarrhythmias), Biventricular dilated cardiomyopathy (→HF) with apical atrophy (→ventricular aneurysm), mural thrombi (→stroke)
2) Gastrointestinal disease: Megaesophagus and achalasia (dysphagia, weight loss, regurgitation), Megacolon (sigmoid, rectum 80%) (abdominal pain, chronic constipation)
Confirmatory Tests
- check Acute phase (including transplants, transfusions), congenital disease, reactivation in immunosuppressed:
1) Thin and thick peripheral smears using Giemsa stain (visualization of T. cruzi trypomastigotes)
2) PCR (T. cruzi DNA) (only available at CDC)
- check Indeterminate and Chronic phase:
serological EIA and immunoblot (TESA) → if discordant IFA) assays to detect IgG antibodies against T. cruzi
Treatment - Primary Regimens:
• Standard regimen: Adult (Age 212 years): Benznidazole 5-7 mg/kg/day po divided into 2 doses (q12h)x60 days
• Pediatric (Age <12 years): Benznidazole 7.5 mg/kg/day po in 2 doses (q12h)x 60 days
Treatment - Alternative Regimens:
• Adult (Age >16 years): Nifurtimox 8-10 mg/kg/day po divided x 90-120 days
• Pediatric:
Age <10 years: Nifurtimox 15-20 mg/kg/day po divided x 90 days
Age 11-16 years: Nifurtimox 12.5-15 mg/kg/day po divided 3-4x/day x 90 days
Dr. Jorge Cortés @Jcortesizaguirr
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