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Chagas Disease

Summary

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  • Chagas disease is a parasitic infection caused by Trypanosoma cruzi
  • Transmitted primarily by triatomine bugs in endemic areas of Latin America
  • Characterised by acute and chronic phases, with potential cardiac and gastrointestinal complications1

Pathophysiology

  • Caused by the protozoan parasite Trypanosoma cruzi
  • Transmission:
    • Vector-borne: Triatomine bugs (kissing bugs)
    • Non-vector: Blood transfusion, organ transplantation, congenital transmission
  • Disease progression:
    1. Acute phase: High parasitaemia, mild symptoms
    2. Indeterminate phase: Asymptomatic, low parasitaemia
    3. Chronic phase: Organ damage (cardiac, gastrointestinal)

Demographics

  • Endemic in 21 Latin American countries
  • Estimated 6-7 million people infected worldwide
  • Increasing prevalence in non-endemic areas due to migration
  • Risk factors:
    • Living in rural areas with poor housing conditions
    • Poverty and lack of access to healthcare

Diagnosis

  • Acute phase:
    • Microscopic examination of blood smears
    • PCR for T. cruzi DNA
  • Chronic phase:
    • Serological tests (ELISA, IFA, RIPA)
    • At least two positive tests required for confirmation
  • Diagnostic challenges:
    • Low sensitivity in chronic phase due to low parasitaemia
    • Cross-reactivity with other parasitic infections

Imaging

  • CNS disease occurs chiefly as reactivation in immunocompromised patients (e.g. HIV), producing a necrotising encephalitis / "chagoma"
  • MRI:
    • One or several ring- or peripherally-enhancing lesions with surrounding vasogenic oedema, favouring the white matter and basal ganglia
    • Variable haemorrhage; the principal differential is toxoplasmosis
  • Systemically, Chagas causes a dilated cardiomyopathy and mega-oesophagus/megacolon

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  • A 25-year-old patient presented with reduced GCS and headache.
  • CT and MRI showed multiple peripherally enhancing lesions with surrounding vasogenic oedema without diffusion restriction.
  • A new diagnosis of HIV was made with a CD4 count of less than 5. PCR was positive for T. Cruzi.

Treatment

  • Antiparasitic therapy (benznidazole or nifurtimox), plus antiretrovirals in reactivation disease

Differential diagnosis

Differential Diagnosis Distinguishing Feature
Toxoplasmosis Multiple ring-enhancing lesions with eccentric target sign, favours basal ganglia and grey-white junction
Primary CNS lymphoma Homogeneously enhancing periventricular lesion with restricted diffusion
Tuberculoma Ring-enhancing lesion with central T2 hypointensity; often with basal meningitis
Cerebral abscess Ring-enhancing lesion with marked central DWI restriction
Cerebral metastasis Enhancing lesion at grey-white junction with extensive vasogenic oedema
Cardioembolic infarct Multi-territory wedge-shaped cortical DWI restriction

  1. de Sousa et al. Chagas disease. 2024. Lancet (London, England) - Open in new tab. ↩